I have a 1998 Pymouth Grand Voyager. The AC was working up to yeseterday. I stopped for an appointment - then BAM! Stopped working.

I noticed that the AC compressor clutch is not engaging. So after checking the forums and alldata.com, I tried to recharge the AC. I purchased a filler with a gauge from walmart and two cans of R134A (without bootser or leak preventor as I read that is bad stuff). When I put the connector on what I believe is the low charge side (large hose and the only connector that the kit fit on), the gauge on the connector was pegged in the red and no R134A would go to the AC unit when I pressed the trigger. I could release R134A without it connected and could feel warm gas going into the can at one time when I was trying to charge.

So here are my questions;

1) Is there something funky about recharging Plymouth systems that prevents you from using an over-the-counter kit?
2) How can I check the low pressure sensor? It has three connections - power, ground, and sensor. Alldata.com had a diagram and I am not sure I can jump this to bypass the sensor to see if it's the sensor or my ac unit. Ideas?

Any help is greatly appreciated!
THANK YOU ,
Fred

No there is nothing funky about recharging Plymouth systems that prevents you from using an over-the-counter kit. If your gauge was pegged in the red, your systems is not low, pressure should fall into the normal area once the compressor runs. Check the pressure sensor with a multimeter. Check your A/C relay as well.


I have a 1998 Pymouth Grand Voyager. The AC was working up to yeseterday. I stopped for an appointment - then BAM! Stopped working.

I noticed that the AC compressor clutch is not engaging. So after checking the forums and alldata.com, I tried to recharge the AC. I purchased a filler with a gauge from walmart and two cans of R134A (without bootser or leak preventor as I read that is bad stuff). When I put the connector on what I believe is the low charge side (large hose and the only connector that the kit fit on), the gauge on the connector was pegged in the red and no R134A would go to the AC unit when I pressed the trigger. I could release R134A without it connected and could feel warm gas going into the can at one time when I was trying to charge.

So here are my questions;

1) Is there something funky about recharging Plymouth systems that prevents you from using an over-the-counter kit?
2) How can I check the low pressure sensor? It has three connections - power, ground, and sensor. Alldata.com had a diagram and I am not sure I can jump this to bypass the sensor to see if it's the sensor or my ac unit. Ideas?

Any help is greatly appreciated!
THANK YOU ,
Fred

OK -checked the pressure sensor with a olm meter. Getting readings between all pins - but not short and not open. Not sure and can't find what those readings should be. Getting 5V to sensor with car running. No short on plug. Checked the plug to compressor - NO VOLTS. Swapped relay with blower relay and checked fuse.

So fo some reason the PCM is not turning on the compressor clutch. I could find very little on this on alldata.com - but the way it works is the sensor sends a signal to PCM. PCM checks if too low or too high of pressure before grounding the relay to turn on the compressor clutch.

So.... I think I may just swap out the pressure sensor and see if it fixes if it's not too expensive.

An ideas or suggestions are appreciated.

With low refrigerant level you should get a short between pin 1 & 3 of the switch. With normal or high refrigerant level you should get a short between pin 2 & 3 of the switch.

Pin 1 BK/LB Ground
Pin 2 VT/WT 5 volt supply
Pin 3 DB A/C pressure sensor signal = common wire.


OK -checked the pressure sensor with a olm meter. Getting readings between all pins - but not short and not open. Not sure and can't find what those readings should be. Getting 5V to sensor with car running. No short on plug. Checked the plug to compressor - NO VOLTS. Swapped relay with blower relay and checked fuse.

So fo some reason the PCM is not turning on the compressor clutch. I could find very little on this on alldata.com - but the way it works is the sensor sends a signal to PCM. PCM checks if too low or too high of pressure before grounding the relay to turn on the compressor clutch.

So.... I think I may just swap out the pressure sensor and see if it fixes if it's not too expensive.

An ideas or suggestions are appreciated.

Thanks for the info...

So - I was so excited this was my problem and went out and tried to find the part. Reibies, Napa, and Auto Zone - nada. They say there is no part on file. So I went to the local wreckers and pulled a sensor off a junked 98. It doesn't work either. I could have two bad ones, but need to confirm something.

When say you a 'short', you mean 0 ohms?

Cause for both units, I get K olms readings on and off the car.

on Car -
pin 1-3 18.26K ohms
pin 2-3 29.07K ohms
pin 2-1 24.73K ohms

These readings are for my 'old' sensor - and the junk yard one is similar - but not exact.

Can I just put a jumper between pins 2-3 to bypass the sensor and see if the PCM will turn on compressor clutch? I am afraid to as I don't want to fry my PCM.

Help is much appreciated!

THANK YOU!

You should get 0 ohms or close to it, your readings seem high. You can jump pins 2 and 3 to see if it works. All the sensor does is switch pin 3 between pin 1 and 2 depending on pressure. Just dont short pin 1 and 2 and you will be okay. If thats the problem try an A/C shop or dealership.


Thanks for the info...

So - I was so excited this was my problem and went out and tried to find the part. Reibies, Napa, and Auto Zone - nada. They say there is no part on file. So I went to the local wreckers and pulled a sensor off a junked 98. It doesn't work either. I could have two bad ones, but need to confirm something.

When say you a 'short', you mean 0 ohms?

Cause for both units, I get K olms readings on and off the car.

on Car -
pin 1-3 18.26K ohms
pin 2-3 29.07K ohms
pin 2-1 24.73K ohms

These readings are for my 'old' sensor - and the junk yard one is similar - but not exact.

Can I just put a jumper between pins 2-3 to bypass the sensor and see if the PCM will turn on compressor clutch? I am afraid to as I don't want to fry my PCM.

Help is much appreciated!

THANK YOU!

Found some info on alldatafyi.com... Have to do a lot of research and put the pieces together. It's not all in one place or really obvious.

1) Verify refrig charge - done, OK
2) Verify volts at ac pressure sensor @ pin 2 - done, OK
- so PCM is working
3) Check for voltage at compressor clutch, done, 0 volts
- so no voltage at compressor clutch
- check relay and fuse - done, OK
- a/c pressure switch is suspect
4) This is what I have to try now
- Check volts from a/c pressure switch indicating signal for low/good/high
- They say to use DRB scann tool, which I don't have, so I will pierce the
signal wire at pin 3 of the ac pressure switch
* 0 volts = bad pressure switch (ps) or 0 volts from PCM
* .150 to.450 volts = ps good, low pressure cut out condition
* .451 to 4.519 volts = Normal operating condition
* 4.520 to 4.850 volts = ps good, High pressure cut out condition
* 5 volts = bad ps

I tried looking up ohms / kirchoffs laws to calculate results from my readings at the begining of this post, but that's too much brain work.

I called a plymouth dealer today and they want $123.90 for a new ac pressure switch. Going to check this one last item to confirm. If this is not it, I could have a some bad wiring or connector which will really be a b*tch to figure out. I hope this is it.

Interesting results -

1) I am getting .925 volts at pin 3 on the ac pressure sensor - which is within the published range of .451 - 4.519 for 'normal' pressure
2) I bypassed the relay and jumped pins 87-30 on the fuse block and the compressor clicked on immediately! Blew cold air.

So conclusion right now is that;
1) Relay is good because I swapped it with the blower relay and the blower works with this ac compressor relay. This should be a good test of the relay, right?
2) Fuse is good, verified by sight and an ohm meter, and the compressor engages when the relay is jumped.
3) Compressor clutch works just fine.

It appears that the PCM is either not getting the signal from the ac pressure sensor or it is not switching the relay on for some reason.

I think I may have to break down and buy a code reader to see what's going on in the PCM.

Any suggestions or ideas is appreaciate!
THANK YOU!

I seen something just like this on a Town car a month ago. Even went as far as swapping the TPS with another that I had sitting around, it turned out to be a bad climate control unit (dash controls) that did not send a compressor on signal when the A/C botton was pressed.

Interesting results -

1) I am getting .925 volts at pin 3 on the ac pressure sensor - which is within the published range of .451 - 4.519 for 'normal' pressure
2) I bypassed the relay and jumped pins 87-30 on the fuse block and the compressor clicked on immediately! Blew cold air.

So conclusion right now is that;
1) Relay is good because I swapped it with the blower relay and the blower works with this ac compressor relay. This should be a good test of the relay, right?
2) Fuse is good, verified by sight and an ohm meter, and the compressor engages when the relay is jumped.
3) Compressor clutch works just fine.

It appears that the PCM is either not getting the signal from the ac pressure sensor or it is not switching the relay on for some reason.

I think I may have to break down and buy a code reader to see what's going on in the PCM.

Any suggestions or ideas is appreaciate!
THANK YOU!

Well that's comforting - as I have ordered a replacement and just waiting for it to arrive. My vent controls were not working - so I am hoping it will fix that problem too.

I found a quarter in mine - so it may have shorted.

I'll post the result of installing the replacement when it arrives.

THANK YOU!

Part of the reason you were unable to recharge is that the compressor needs to be running in order to "suck in" the charge.

I'd recommend posting your question at www.autoacforum.com (http://www.autoacforum.com) to get advice from people who specialize in A/C system diagnosis & repair. I've found answers to a LOT of A/C-related questions over there.

Webch -

Thank you for your advice. As I mentioned, I do have a good charge as the ac pressure sensor is sending a .9 V signal from the sensor lead which is within the specified range for 'normal'. Although I will run the compressor tonight with a gauge on it to confirm.

I will also post my problem on the forum you mentioned. That is an excellent suggestion!

THANK YOU!

Hey before you spam other forums on here, you might want to check with a MOD before you buy yourself a vacation.



Part of the reason you were unable to recharge is that the compressor needs to be running in order to "suck in" the charge.

I'd recommend posting your question at www.autoacforum.com (http://www.autoacforum.com) to get advice from people who specialize in A/C system diagnosis & repair. I've found answers to a LOT of A/C-related questions over there.

You need to test the pressure with a gauge not a volt meter. And hopefully you are hooking up the gauge you bought at walmart to the low pressure side only. Unless you want to take a trip to the hospital.

Hey before you spam other forums on here, you might want to check with a MOD before you buy yourself a vacation.

Just trying to help someone get an answer to their question. If the moderator has a problem with that, he or she can PM me. The idea that I'm getting any form of kickback by recommending that site is laughable. I wish! I could use a vacation right now to get out of the 110 °F weather here. I have absolutely no affiliation with that site, or the the A/C shop that funds its existance, other than a satisfied customer (of the shop). I only recommend it because I've gotten knowledgeable A/C specific information from that site in the past, and they have numerous tutorials and other information on the basics of A/C systems, and are not hostile toward the DIY (something rare when one attempts to learn how to do A/C repairs at A/C-specific sites I've found).

There's no one site that has all the answers. It's a shame you cannot see that. This site is great as well and has helped me solve several critical problems with my van. Granted, my most recent posts have been A/C related (and I do tend to recommend that site frequently), but that is only because it's that time of year again, and I'm currently involved in a thorough A/C system repair on my friends vehicle. Lighten up!

Hey before you spam other forums on here, you might want to check with a MOD before you buy yourself a vacation.

Not to worry. Posting another forum link doesn't appear to be a problem. It's just as likely a link to this forum is posted on other forums. It goes both ways.

OBTW - I believe GPT Dad, a moderator at one time, left the forum many moons ago. I think they are still looking to "hire" a replacement moderator on the Caravan forum.

OK - Got the new control panel and my vent controls work and it passed calibration now.

AC compressor still didn't kick in so I bypassed the relay thinking maybe that I am low on refridgerant. Well, the loud squeeling noise :eek7: came shortly after that and I can see the high pressure vent is venting.

I don't want to screw anything else up - so what would cause this?

THANKS!

This is not a good sign, and can be a few things even a plugged oriface tube, hard to say without high side readings. At this point it might be a good idea to seek the help of a good A/C shop as this repair if nothing else is going to need tools that you more then likely do not have. When your high pressure vent starts venting it tells me that you have extreme pressure on the high side, The venting valves are set up to vent when the high side hits between 500-600PSI. At this point if you have a weak hose it can blow up as you are standing over it. This repair is not worth the money you save by trying to do the repair at home. The damage this can do even if you do not get hurt can far out weight the cost of having a pro deal with it.



OK - Got the new control panel and my vent controls work and it passed calibration now.

AC compressor still didn't kick in so I bypassed the relay thinking maybe that I am low on refridgerant. Well, the loud squeeling noise :eek7: came shortly after that and I can see the high pressure vent is venting.

I don't want to screw anything else up - so what would cause this?

THANKS!

Ok - Thank you for the advice. It's time to seek the help of a professional.

When it gets fixed, I'll post results here.

Thanks!

OK - I am now a Darwin Award winner!

In my zeal to install and test my newly arrive climate control panel - I negelected to check if I reconnected the AC pressure sensor. :banghead:

I plugged it in, ran cool down test, and BAM!!!! I was able to top off the system with a can of refr and the low side is icy cold!:naughty:

Problem solved by replacing the climate control panel.:lol2: