Dual climate control blowing heat on AC (DCCV removal instructions in post #107)

Well Im back with a new problem.

If you set the AC to a set temp and after a while you decide its too cold and change the temp up a little or a lot, the drivers side will start blowing hot air.

But the passenger side stays cold.

So I have to leave the temp set and change the fan speed to keep this from happening.

Any ideas?

Sounds like you have a blend door motor that may not be functioning properly. Have you run the climate control self diagnostics? If you've never done this, it may be posted on the forum (perform a search) or I'll try to round up the procedure tonight from the service manual.

-Rod

Per the factory service manual, below are the steps to pull diagnostic codes from the HVAC system:
Front Panel DATC Module Self-Test (On-demand Diagnostic Trouble Codes—DTCs)
On-demand DTCs are those that are reported by an ECU when a failure is detected while executing a diagnostic test. For the DATC module this means that all faults (hard) that occur while the module is conducting a self-test shall be reported as an on-demand DTC.
The DATC module self-test will not detect concerns associated with data link messages such as engine coolant temperature or vehicle speed signals. The scan tool must be used to retrieve these concerns.
The vehicle interior temperature should be between 0-32°C (32-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false temperature sensor DTCs may be displayed.The DATC module self-test through the front panel display:
can be initiated at any time. Normal operation of the system stops when the self-test is activated.
is entered by pressing the OFF and FLOOR buttons simultaneously and then pressing the AUTO button within two seconds. The display will show counts of 1 to 25 in the center of the display window. Record all DTCs displayed.
concludes by reporting all on-demand DTCs. Follow the diagnostics procedure given under ACTION in the DTC index for each DTC given.
reports individual on-demand DTCs as four-digit DTCs (less the alpha character).
will calibrate all the mode doors and check all analog inputs. The DATC module will only report on-demand (hard) faults that occurred while the DATC module was conducting its self-test.
will light all control panel display segments if no faults are detected.
will report individual on-demand DTCs without the °C symbol lit.To exit the self-test, press any button. This will clear all on-demand codes from the DATC module memory. If no button is pushed DTCs will continue to be displayed.
Upon exit from the self-test the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
If a condition exists but no DTCs appear during the self-test, GO to Symptom Chart (http://www.automotiveforums.com/vbulletin/S2X%7Eus%7Een%7Efile=S2XC0003.htm%7Egen%7Eref.htm# SC1)Condition: The DATC System Is Inoperative, Intermittent or Incorrect Operation.
Always exit the self-test before powering the system down (system turned OFF).
Front Panel DATC Module Display—Retrieve Continuous Diagnostic Trouble Codes (DTCs)
Continuous DTCs are fault codes recorded by the DATC module which have occurred during normal operation. For the DATC module this means that all faults (intermittent or hard) that occur while the module is in an operational state shall be reported as a continuous DTC.
To retrieve continuous DTCs, press the OFF and PANEL buttons simultaneously, followed by pressing the AUTO button within two seconds.
The DATC module will report all continuous DTCs to the vacuum fluorescent (VF) display.
The DATC module will not carry out a self-test; it will only display continuous faults codes which are stored in memory.
All VF display segments will light if no faults are detected.
Individual continuous DTCs will be reported with the °C symbol lit.
DTCs shall be reported as a four-digit DTC (less the alpha character).
Pressing the front defrost button will exit the retrieve continuous DTCs mode and clear all continuous DTCs from DATC module memory.
Pressing any other button (other than DEFROST) will exit the retrieve continuous DTCs mode and maintain all continuous DTCs in DATC module memory.
Upon exit from the retrieve continuous DTCs mode the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.If the procedures above yield any codes, post back and I'll give you the description for the code.

-Rod

Rod,

Your the greatest.:thumbsup: I will print this out and give it a try.

Per the factory service manual, below are the steps to pull diagnostic codes from the HVAC system:
Front Panel DATC Module Self-Test (On-demand Diagnostic Trouble Codes—DTCs)
On-demand DTCs are those that are reported by an ECU when a failure is detected while executing a diagnostic test. For the DATC module this means that all faults (hard) that occur while the module is conducting a self-test shall be reported as an on-demand DTC.

The DATC module self-test will not detect concerns associated with data link messages such as engine coolant temperature or vehicle speed signals. The scan tool must be used to retrieve these concerns.
The vehicle interior temperature should be between 0-32°C (32-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false temperature sensor DTCs may be displayed.The DATC module self-test through the front panel display:

can be initiated at any time. Normal operation of the system stops when the self-test is activated.
is entered by pressing the OFF and FLOOR buttons simultaneously and then pressing the AUTO button within two seconds. The display will show counts of 1 to 25 in the center of the display window. Record all DTCs displayed.
concludes by reporting all on-demand DTCs. Follow the diagnostics procedure given under ACTION in the DTC index for each DTC given.
reports individual on-demand DTCs as four-digit DTCs (less the alpha character).
will calibrate all the mode doors and check all analog inputs. The DATC module will only report on-demand (hard) faults that occurred while the DATC module was conducting its self-test.
will light all control panel display segments if no faults are detected.
will report individual on-demand DTCs without the °C symbol lit.To exit the self-test, press any button. This will clear all on-demand codes from the DATC module memory. If no button is pushed DTCs will continue to be displayed.
Upon exit from the self-test the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
If a condition exists but no DTCs appear during the self-test, GO to Symptom Chart (http://www.automotiveforums.com/vbulletin/S2X%7Eus%7Een%7Efile=S2XC0003.htm%7Egen%7Eref.htm# SC1)Condition: The DATC System Is Inoperative, Intermittent or Incorrect Operation.
Always exit the self-test before powering the system down (system turned OFF).
Front Panel DATC Module Display—Retrieve Continuous Diagnostic Trouble Codes (DTCs)
Continuous DTCs are fault codes recorded by the DATC module which have occurred during normal operation. For the DATC module this means that all faults (intermittent or hard) that occur while the module is in an operational state shall be reported as a continuous DTC.

To retrieve continuous DTCs, press the OFF and PANEL buttons simultaneously, followed by pressing the AUTO button within two seconds.
The DATC module will report all continuous DTCs to the vacuum fluorescent (VF) display.
The DATC module will not carry out a self-test; it will only display continuous faults codes which are stored in memory.
All VF display segments will light if no faults are detected.
Individual continuous DTCs will be reported with the °C symbol lit.
DTCs shall be reported as a four-digit DTC (less the alpha character).
Pressing the front defrost button will exit the retrieve continuous DTCs mode and clear all continuous DTCs from DATC module memory.
Pressing any other button (other than DEFROST) will exit the retrieve continuous DTCs mode and maintain all continuous DTCs in DATC module memory.
Upon exit from the retrieve continuous DTCs mode the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.If the procedures above yield any codes, post back and I'll give you the description for the code.

-RodI tried this procedure due to my own problems and it doesn't work. What am I doing wrong. I press the off and combo panel, floor, vent, button and then the auto button. Nothing happens except it goes into auto.

What year LS are you trying this procedure on? Are you following the steps precisely? Read the first step again. What you typed you're doing does not agree with step 1 for either of the procedures.

-Rod

There's a electronic control hot water pump for Dual climate controls.
1) When the car is at normal operating cond,turn off Car engine.
2) Turn on Ignition switch to the on pos,this will activate the pump,so you can
have heat in car while Eng is off.
3) This will force the hot water through the Dual climate control solenoid.
4) Check Anti-freeze level! (Air-pockets)
5) If your still having Tbl ,it could be the Dual climate control solenoid.

I had to take mine apart and cleaned with WD40.:smokin:


** It's a good ideal to exercise this switch during the summer months.


Note: Running this electric pump is a good way of working out air pockets
during radiator flush treatments.

What year LS are you trying this procedure on? Are you following the steps precisely? Read the first step again. What you typed you're doing does not agree with step 1 for either of the procedures.

-RodIt's a 2004. There is no floor button or panel button. It is one button you press to get different controls. You press once, it's def, you press again, it's panel, again floor, again, panel and floor. ETC Something like that but no seperate buttons for floor, panel and def. I'm not missing any procedure. I tried it over and over.

So you have the climate controlled seats. You tried turning the controller off, then simultaneously pressing both the Off and Ventilation switches, releasing and quickly pressing Auto? I don't know if starting with the unit off will help or not.

I don't have the manual for 2004, the procedure above is for 34Ford's 2001.

-Rod

The problem is the self test feature is different for the 2003-2006 LS cars with the heated/cooled seats. I went thru hell to find it and finally took it to the dealer only to find out they did not know either!! So the mechanic called the hot line and got the correct instructions.


Ignition needs to be on. Car can be running or not. Push the OFF and the DEFROST buttons at the same time. Then press the AUTO button. You are now in self test mode. Let it run and you should get all 8's and every light segment lighted if everything is good. Otherwise write down the numbers displayed. The trouble codes are listed in the Helm shop manual. Push any button to end the test.

You might want to save a copy of this. IT IS NOT IN THE HELM MANUAL!!! All of Ford/Lincoln service materials are wrong or don't even mention the differences.
.
.
.

Now that is some great info. Thanks. Everything works fine now but maybe for future reference.

a quick workaround that seemes to work when the AC is blowing cold and hot air.

hit auto, turn the temp all the way up to make it blow heat then turn the temp back down to cold. hit auto.

sounds goofy but it has worked several times for me.

Shorod
I'm not sure that I'm asking this question in the right place where you would get it, but here goes.

I notice you recommend pulling the DTC's from the AC on the Lincoln LS. I've done that with my car but I need to know the description of the error. It is reading 12 61.

Can you help?

The code 12 61 designates A/C solar radiation sensor circuit short to ground. The solar radiation sensor is the little dark bulb on the top of the dash board.

-Rod

I replaced the air temp sensor. Now I am getting the following codes: 12 59 and 50 41. What are these?

Thanks

The code 12 59 indicates an issue, like your previous code of 12 61, with the solar radiation sensor, A/C solar radiation sensor open circuit.

Code 50 41 indicates SCP invalid or missing data for function read vehicle speed.

Is there a chance you didn't get one of the connectors seated properly when you replaced the temp sensor? Is there a reason you replaced the air temp sensor when your code indicated an issue with the solar radiation sensor?

-Rod

The code 12 59 indicates an issue, like your previous code of 12 61, with the solar radiation sensor, A/C solar radiation sensor open circuit.

Code 50 41 indicates SCP invalid or missing data for function read vehicle speed.

Is there a chance you didn't get one of the connectors seated properly when you replaced the temp sensor? Is there a reason you replaced the air temp sensor when your code indicated an issue with the solar radiation sensor?

-Rod
I replaced the sensor on top of the dash. The little black bubble that is farthest away from the windshield. (I believe the other black bubble has to do with the secutrity?)

I was told at the Lincoln dealership this was called the air temp sensor so that's what I called it.

I just plugged it in and tried the AC. It didn't help, so I tried the diagnostic test again. The results were 12 59 and 50 41.

Could to explain the 50 41?

Thanks

I don't recall what SCP stands for, Serial Communications Protocal? I don't believe it's "Serial" but don't recall what it is. Anyway, apparently the vehicle speed input for the CAN protocol system is not present. Does the speedometer and cruise control work? Try scanning the powertrain codes and see if you get a similar speed sensor error from the power train system.

It sounds like a connector somewhere got left off, causing the open condition for the solar radiation sensor and possibly the missing speed sensor information.

For what it's worth, the solar radiation sensor is not a temperature sensor, but rather a light sensor.

-Rod

I ran the self test and came up with two codes:

12 63, 16 76

Does anyone know what they mean?

Justin
jrcherry821@yahoo.com

I left the solar radation sensor unpluged while I waited for the new one to come in. Would that expain any of the previous codes?

Prior to removing the sensor the air conditioner went out completely. A mechanic found a blown fuse in the Power Distribution Box under "HEGO's". I'm not sure what caused this.

Now the air conditioner is back to the same problem of blowing out heat and cool air at the same time if you change the temp. setting. If I stop and turn off the engine for a while and come back later and start it the air conditioner works fine unless I change the temp. setting.

When I change the temp settings or cut the air conditioner off you can hear the blend door shutting. I read on here somewhere that the blend door is operated electronically. How do you check it. Also, that the air conditioner has a thermostat or the Dual Coolant Control Valve could be sticking. Do you know anything about these?

I recently has an emission light come on but, I think it to be a seperate issue. I had the code pulled on it and it stated: 02 heater circut (bank 1 Sensor 2). A rock flipped up and it hit the undercarriage the day this light came on. I was thinking it may have knocked my a wire on my 02 sensor loose.

I ran the self test and came up with two codes:

12 63, 16 76

Does anyone know what they mean?

Justin
jrcherry821@yahoo.com

Welcome to the forum!

Code 12 63 is Panel door actuator circuit failure and code 16 76 is Battery voltage out of range.

-Rod

I left the solar radation sensor unpluged while I waited for the new one to come in. Would that expain any of the previous codes?

Prior to removing the sensor the air conditioner went out completely. A mechanic found a blown fuse in the Power Distribution Box under "HEGO's". I'm not sure what caused this.

Now the air conditioner is back to the same problem of blowing out heat and cool air at the same time if you change the temp. setting. If I stop and turn off the engine for a while and come back later and start it the air conditioner works fine unless I change the temp. setting.

When I change the temp settings or cut the air conditioner off you can hear the blend door shutting. I read on here somewhere that the blend door is operated electronically. How do you check it. Also, that the air conditioner has a thermostat or the Dual Coolant Control Valve could be sticking. Do you know anything about these?

I recently has an emission light come on but, I think it to be a seperate issue. I had the code pulled on it and it stated: 02 heater circut (bank 1 Sensor 2). A rock flipped up and it hit the undercarriage the day this light came on. I was thinking it may have knocked my a wire on my 02 sensor loose.

Yep, if the codes were not cleared prior to reconnecting the new solar radiation sensor, that would explain the code 12 59.

Unfortunately I'm fighting a very similar issue to yours, except I get no codes. I've also replaced the DCCV with no change and even tried a second control head, no difference. On my wife's 2002, we need to turn the set point down to 60 in order to get it blowing cold. If we turn it up to 65, it may start blowing warm. If it starts blowing warm, then we turn it back to 60 for a minute or two, then back to 65, it will continue blowing cold and the fan speed may slow down a step or two. It soon gets too cold, but if set the temp setting all the way up to 85 (max) it will still be blowing cold air. This is even when the outside temp is around 80.

No DATC diagnostic codes, a brand new OEM DCCV, new battery (recently), different control head, and the R-134a pressures are at specification.

-Rod

I am having same issue with heat blowing while running ac. I print and tried shorod diagnostic steps but nothing at all happen.

Lincoln Ls V6 2002

Any idea?

Hmmm, did you have the key in the "Run" position at the time? You need to press both the Off and Floor buttons at the same time, then release both buttons and within 2 seconds press the Auto button. That should initiate the process.

-Rod

The problem is the self test feature is different for the 2003-2006 LS cars with the heated/cooled seats. I went thru hell to find it and finally took it to the dealer only to find out they did not know either!! So the mechanic called the hot line and got the correct instructions.


Ignition needs to be on. Car can be running or not. Push the OFF and the DEFROST buttons at the same time. Then press the AUTO button. You are now in self test mode. Let it run and you should get all 8's and every light segment lighted if everything is good. Otherwise write down the numbers displayed. The trouble codes are listed in the Helm shop manual. Push any button to end the test.

You might want to save a copy of this. IT IS NOT IN THE HELM MANUAL!!! All of Ford/Lincoln service materials are wrong or don't even mention the differences.
.
.
. So do you know which buttons to press for a '05 V6 LS without cooled and heated seats, I tryed it every which way and have never seen a self test pop up, I'd really like to get my AC going again without having to go to a dealer....

Well, for the 2004 there is not a designation between the process for DATC with climate controlled seats versus without. Did all V8 models have climate controlled seats?

The manual claims you access the codes with the following sequence:
------------
The DATC module self-test through the front panel display:
can be initiated at any time. Normal operation of the system stops when the self-test is activated.
is entered by pressing the OFF and FLOOR buttons simultaneously and then pressing the AUTO button within two seconds . Record all DTCs displayed.
concludes by reporting all on-demand DTCs. Follow the diagnostics procedure given under ACTION in the DTC index for each DTC given.
reports individual on-demand DTCs as four-digit DTCs (less the alpha character).
will calibrate all the mode doors and check all analog inputs. The DATC module will only report on-demand (hard) faults that occurred while the DATC module was conducting its self-test.
will light all control panel display segments if no faults are detected.
will report individual on-demand DTCs without the °C symbol lit.

To exit the self-test, press the defrost button. This will clear all on-demand codes from the DATC module memory. If no button is pushed, DTCs will continue to be displayed.

Upon exit from the self-test the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
------------

For what it's worth, I'm claiming success in getting the issue fixed on my wife's LS. My scan tool showed that the Evaporator Core Air Discharge temp sensor was not in range. There were no codes, but the datastream showed no changes in the reading and it appeared to be maxed out at 255 degrees F, even when the vent temp was 45 degrees F. Replaced the sensor and all has been well for 2 weeks of mixed weather.

-Rod

Hi, I'm new to the post and my 2004 V-8 is blowing hot air whenever I turn on the a/c or recirculate.The temp from 60 to 90 is still hot. I performed the self test and got the code 27 98. Do u have any ideas about this one? It's 100 degrees in GA!! :)

Welcome to the forum!

Your code 2798 means the driver side coolant control valve circuit is shorted to ground. Looks like you pretty much have proof that you need a new DCCV.

-Rod

Welcome to the forum!

Your code 2798 means the driver side coolant control valve circuit is shorted to ground. Looks like you pretty much have proof that you need a new DCCV.

-Rod
Thanks Rod,
I'm ordering one ASAP. :bigthumb:

Same thing here. 2002 lincoln ls AC problem. Blowing nothing but hot air. I ran the Diagnostic and was given this code:

19 47

Any suggestions?
And where is the index of DTC

Code 1947 indicates that there is a short circuit to ground in the Evaporator Discharge Temperature Sensor circuit. You can start by pulling and the lower of the two temp sensors on the driver's side which is discussed in this thread. The lower sensor is the sensor in question. Check the sensor and wiring for the sensor for a short to ground.

-Rod

the sensor that you mentioned, where is it and how do i go about removing it? should i just replace the sensor or troubleshoot further?

the sensor that you mentioned, where is it and how do i go about removing it? should i just replace the sensor or troubleshoot further?

Click on the "in this thread" hyperlink from my previous post in this thread. As I mention, although it may not be clear, the Evap discharge sensor is the lower of the two sensors on the driver's side of the center plenum.

-Rod

Welcome to the forum!

Your code 2798 means the driver side coolant control valve circuit is shorted to ground. Looks like you pretty much have proof that you need a new DCCV.

-Rod

Hi,
Is the part that I need also called a heater control valve and is it located adjacent to the radiator? One dealer mechanic told me that there are two valves, one located in the dash and one located under the hood. Could someone please clarify?

The Dual Coolant Control Valve (DCCV) is located under the hood near the radiator. It has two valves in it which regulates the flow of coolant to the dual heater core elements inside the car. There is no valve for the coolant flow inside the car/under the dash. Hopefully the dealer technician that told you that will not be the one working on your car.

On older cars, the heater control valve did serve a very similar purpose to the DCCV, but was often vacuum actuated (DCCV is electronically actuated). Someone who's been in the business awhile may refer to the DCCV as a "heater control valve."

-Rod

The Dual Coolant Control Valve (DCCV) is located under the hood near the radiator. It has two valves in it which regulates the flow of coolant to the dual heater core elements inside the car. There is no valve for the coolant flow inside the car/under the dash. Hopefully the dealer technician that told you that will not be the one working on your car.

On older cars, the heater control valve did serve a very similar purpose to the DCCV, but was often vacuum actuated (DCCV is electronically actuated). Someone who's been in the business awhile may refer to the DCCV as a "heater control valve."

-Rod
The techician who told me there were two isn't fixing my car. Do you have the part number?

Do you have the part number?

It's rare for me to throw anything away, but apparently that's one item that I did.

-Rod

It's rare for me to throw anything away, but apparently that's one item that I did.

-Rod
The part i found was YG378-heater control valve by Motorcraft.

Well, for the 2004 there is not a designation between the process for DATC with climate controlled seats versus without. Did all V8 models have climate controlled seats?

The manual claims you access the codes with the following sequence:
------------
The DATC module self-test through the front panel display:
can be initiated at any time. Normal operation of the system stops when the self-test is activated.
is entered by pressing the OFF and FLOOR buttons simultaneously and then pressing the AUTO button within two seconds . Record all DTCs displayed.
concludes by reporting all on-demand DTCs. Follow the diagnostics procedure given under ACTION in the DTC index for each DTC given.
reports individual on-demand DTCs as four-digit DTCs (less the alpha character).
will calibrate all the mode doors and check all analog inputs. The DATC module will only report on-demand (hard) faults that occurred while the DATC module was conducting its self-test.
will light all control panel display segments if no faults are detected.
will report individual on-demand DTCs without the °C symbol lit.

To exit the self-test, press the defrost button. This will clear all on-demand codes from the DATC module memory. If no button is pushed, DTCs will continue to be displayed.

Upon exit from the self-test the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
------------

For what it's worth, I'm claiming success in getting the issue fixed on my wife's LS. My scan tool showed that the Evaporator Core Air Discharge temp sensor was not in range. There were no codes, but the datastream showed no changes in the reading and it appeared to be maxed out at 255 degrees F, even when the vent temp was 45 degrees F. Replaced the sensor and all has been well for 2 weeks of mixed weather.

-RodSorry for slow response , as I have to temp. stop at local library, I've tryed that before and it didnt work, but will try again, there is something I noticed the other day that the air compressor is not kicking off and on.... is there something I can check, it was almost dark when it dawned on me it wasnt clicking off and on..

Is the compressor clutch engaging and staying engaged? If so, that's not really anything to worry about. If it starts cycling rapidly, that would indicate either a low charge of R-134a, an overcharge condition, or some other fault in the system.

-Rod

thank you for all your help. I removed the sensor and nothing was noticeable to the eye or to a multimeter so i swapped it with the upper sensor on the driver side. AC works fine as far as i can tell this fixed the problem. I ran the self diagnostic again and no errors were shown. Should i still replace the sensor that i moved to the top to prevent future problems??

Yep, I'd suggest you still replace it. You swapped it with the driver's side air discharge temp sensor. The air out of the driver's vent may not regulate as well as it should, and maybe that won't become apparent until winter/cold weather.

Considering that the part is only $16.19 MSRP and is pretty easy to replace, I'd change it out. At least your confidence is high that that will fix your concern completely.

FWIW, my bad sensor looked fine and there was no obvious problem based on a multimeter test. However, my scan tool indicated it was bad in the datastream mode, and the readings followed the sensor when I moved it so I was confident I didn't have a wiring issue.

-Rod

Is the compressor clutch engaging and staying engaged? If so, that's not really anything to worry about. If it starts cycling rapidly, that would indicate either a low charge of R-134a, an overcharge condition, or some other fault in the system.

-Rod Sorry for the long delay in answering again, as I still having to stop at library to use pc. I checked fuses again and the 10A fuse in passenger panel was blown. I replaced it and it did not blow again but still blows hot air. I can now hear compressor cycling. It sounds logical that since that fuse covers AC clutch, coolant control valve, aux coolant pump... that maybe the coolant control valve burned out and blew the fuse. It seems like I read somewhere that the coolant control valve is electronic.. what do you think shorod or any other users.. thanx it will be at least monday before I can get back to this..thanx again..

I think you need to figure out how to get the codes (if there are any) from the DATC unit to see if it guides you to any one particular component. The DCCV is an electronically controlled pair of valves, but everything else in that circuit will also be electronic (hence the need for a fuse) and therefore I'm not sure that I'd say the DCCV is more likely to be the problem than the A/C clutch, coolant pump, etc.

-Rod

I think you need to figure out how to get the codes (if there are any) from the DATC unit to see if it guides you to any one particular component. The DCCV is an electronically controlled pair of valves, but everything else in that circuit will also be electronic (hence the need for a fuse) and therefore I'm not sure that I'd say the DCCV is more likely to be the problem than the A/C clutch, coolant pump, etc.

-RodWell the ac clutch is cycling so I guess is't not that, the engine has never ran hotter than half way up on gauge (normal), so the coolant pump I guess is doing its thing. But it sure blows very hot air. Is the DCCV? what switches (moves blend door) or blends temps that come out vents? or that a separate thing? Like say on my caravan I can be using AC and say it gets a little chilly inside, I just hit the AC button to turn it off but let the blower keep blowing and it slowly goes to room air temp air blowing through the vents, but the LS is HOT HOT HOT always no matter what adjustments are made. I Never could get the DATC unit to give up a code. (I have disconnected the battery before , several times) bout ready to take it to a dealer, see if they can tell me whats wrong without having them actually work on it. (like saying I have to save up the money before I can get it fixed)... so now what u think? trade it this winter on a very cold day, LOL

Is it Hot regardless of the set temperature? If you set the temp to 60 degrees, is it still coming out the vents hot? The DCCV is the Dual Coolant Control Valve. It regulates the amount of coolant flow for the driver's and passengers heater cores. If the DCCV is working properly, it should be shutting off coolant flow through both of the cores when the set point is 60 degrees. However, if one or both of the valves are stuck open, or there is a short causing the valves to remain open, you will get constant coolant flow through the cores which will probably overpower the evaporator core chilled/dehumidified air and feel hot at the vents.

If at 60 degrees setpoint the air is cold, then you probably have a sensor issue somewhere.

-Rod

Is it Hot regardless of the set temperature? If you set the temp to 60 degrees, is it still coming out the vents hot? The DCCV is the Dual Coolant Control Valve. It regulates the amount of coolant flow for the driver's and passengers heater cores. If the DCCV is working properly, it should be shutting off coolant flow through both of the cores when the set point is 60 degrees. However, if one or both of the valves are stuck open, or there is a short causing the valves to remain open, you will get constant coolant flow through the cores which will probably overpower the evaporator core chilled/dehumidified air and feel hot at the vents.

If at 60 degrees setpoint the air is cold, then you probably have a sensor issue somewhere.

-RodJust now able to get back with you Rod. No it's Hot no matter what no cold period, run it down to 60 and still Heater HOT both sides. Even if dual is selected or not. So it DOES sound like the DCCV? Right? thanx again...

Yep, it sounds like the DCCV may be stuck open. One additional test would be to unplug the DCCV electrical connector and see if you still get heat. If so, that would indicate the DCCV is stuck open as I believe the DCCV is supposed to open with battery voltage applied. If you remove the battery voltage and the flow of coolant is still to the heater cores, the DCCV is not closing.

I'll have to confirm that the DCCV opens with battery voltage....

-Rod

Yep, it sounds like the DCCV may be stuck open. One additional test would be to unplug the DCCV electrical connector and see if you still get heat. If so, that would indicate the DCCV is stuck open as I believe the DCCV is supposed to open with battery voltage applied. If you remove the battery voltage and the flow of coolant is still to the heater cores, the DCCV is not closing.

I'll have to confirm that the DCCV opens with battery voltage....

-RodGreat, now it sounds like where getting somewhere. so you probably already know I'm going to ask where the DCCV electrical connector is located?, I Don't have CD manual or regular manual.. thanx Rod.

The DCCV electrical connector on the 2002 is located to the left side (as you're standing in front of the car/engine compartment) of the radiator towards the top of the radiator. You can follow the wires down to the DCCV connector which is about 12 inches of wire away. I suspect the 2005 model year is similar. There are three wires in the connector, a brown/green, red/orange, and black/orange.

And from my quick look through the service manual, it does appear that battery voltage opens the solenoids, so unplugging the DCCV should stop the flow of coolant to the heater cores if the DCCV is working.

-Rod

OK, great I'll check that and let you know soon. thanx again Rod.

Thanks for all the good info in this thread. I have a '95 Town Car without dual zone climate control, and it also blows hot air and cold simultaneously when the A/C is running. Just got done replacing the blend door actuator on the advice of a mechanic at the local dealership (what a pain), but that did not solve the problem.

The self-test of the ventilation system control module yielded the codes 0115 and 0125. Do you know the descriptions for these? Thanks much in advance.

Welcome to the forum!

The code 115 is for "Intermittant engine coolant temperature signal" and code 125 is "Intermittant vehicle speed signal."

If you haven't already, you should consider checking the Town Car forum for common issues that may cause these codes. You should also check the PCM diagnostic codes and see if these codes are mirrored there. That may help you determine if the issue is likely with the sensors or with the wires/connections for the EATC system.

-Rod

Thanks for the codes - I thought they might be specific to the heating and A/C system since they came up there on the temperature display after running the self-diagnostic and did not appear when I checked the OBD II codes with a code scanner.

What else would cause the A/C to blow the hot? The pipe from the compressor is cold to the touch and the compressor is engaging. I can hear what sounds like the blend door moving when I press the ventilation control buttons. When the car is first started cold, I have good A/c, but as soon as the engine warms up, the hot air overpowers the cold. Any further ideas would be appreciated. Thanks.

The heater control valve, if stuck open, will cause the symptoms you describe. Also, I found on my wife's LS that a bad AC Evaporator discharge temp sensor will cause heat at any set point other than 60 degrees F.

-Rod

New guy here. Read and followed procedures outlined. Still have hot air from passenger vents. Bad mixture door? Any help would be highly appreciated. Oh yeah, no error codes show up.:banghead:

New guy here. Tried all the procedures on the DTC testing using the panel but recieved no trouble codes displayed. Hot air still present on passenger side. Disconnected the heater control valve but hot air still present. Is it the cause of the trouble?? Please help!!:banghead:

With the DCCV disconnected, it should have allowed full coolant flow if working properly. When the valves receive battery voltage, they close.

Based on my experiences with my wife's DATC and a few others on this forum, I'd suggest switching around the Evaporator Core discharge temp sensor with the driver's side air discharge temp sensor. On the earlier LS, those two sensors are the same part number, along with the passenger side air discharge temperature sensor.

-Rod

Thanks for the info. I will try this out. These are on the air plenum under the dash? I think so, but not sure. I will let you know my results with this test.

Thanks Rod....

Yes, on the 2002 model year they are located on the center plenum, two on the driver's side and one on the passenger side.

-Rod