Climate control blower intermittent when hot

Hi,
I've got a Oldsmobile LSS 1999 equipped with CLIMATE CONTROL, using ACDELCO 15-72200 heater & A/C Control module, the one with passenger control (CJ2 option).

Whenever the car is left under direct sun, the interior fan blower should start at full speed and progressively slow down as the temperature goes down in the car.

For a few weeks, fan often won't run at all (not always), then it goes on for 10-15 seconds and stops again, on and off, for a while. Eventually, it gets back to normal. When this occurs, I am unable to override the fan speed. Display on the dash is normal, but the fan remains silent, regardless to the speed, A/C on or off or selected temperature.

My local mechanic thinks it is "a control box just next to the firewall where the fuses and relays are". All there is at that level is a resistor and relay, no control, so I'm suspicious.

My GM dealer service department thinks it is the control module inside the dashboard that is getting crazy when hot. Unfortunately this part is DISCONTINUED and no longer available from GM Canada. I found a new one announced on the internet, but at 285$ plus shipping, I would rather be 100% sure I'm replacing the right part !!!

Such intermittent behavior is quite hard to troubleshoot and I'm quite concern about the day it will quit working in the middle of a winter storm !!!

Has anybody ever been trough it ? I have been trough the forum and I have not found the same symtoms or the same climate control model.

Thanks

Martin

To avoid guesss work here you need a OE based shop manual and use the "trouble tree" for the symptoms to trace down the source when this occurs.

To avoid guesss work here you need a OE based shop manual and use the "trouble tree" for the symptoms to trace down the source when this occurs.

I do have the GM Service manual on CD. Diagnostic tree is not very helpful on that specific intermitten problem on that system.
So far, prime suspect is a failing Blower Motor resistance, and possible corroded/burned connectors.
Next suspect is Blower Control Module (next to the Blower Motor Resistor and the Blower motor).

If I replace the resistor (often failing and only 22$) and can't find problems with wiring on the front, then the troubleshooting procedure may be helpful.

Next suspect is Blower Control Module (next to the Blower Motor Resistor and the Blower motor).

If I replace the resistor (often failing and only 22$) and can't find problems with wiring on the front, then the troubleshooting procedure may be helpful. The blower control module is a self-contained speed control unit and the CJ2 system does not use any other "resistor" or relays for blower motor control. Did you hear any unusual noises from the fan motor, prior to this intermittent blower speed problem? Usually, when the blower speed control module fails, the fan will run on high speed all the time (even with ignition switch off), or the fan will not run at all. The symptoms you described, tend to point to the blower motor or wiring connectors. You can check the motor full load amperage (if it will run on high speed) to see if it is pulling more than 20 amps. If so, and the motor is failing, it will eventually take the blower control module with it! Check these things first and if you need help finding a new ACDelco control module at ½ the price of the dealer, send me a PM for more info. Good Luck!

BTW, the blower module is located under the fuse/relay panel on the firewall and it takes less than 30-min to change (if you know what you are doing).

Pic of the module below:

http://img177.imageshack.us/img177/3646/bcmfd9.jpg

The blower control module is a self-contained speed control unit and the CJ2 system does not use any other "resistor" or relays for blower motor control. Did you hear any unusual noises from the fan motor, prior to this intermittent blower speed problem? Usually, when the blower speed control module fails, the fan will run on high speed all the time (even with ignition switch off), or the fan will not run at all. The symptoms you described, tend to point to the blower motor or wiring connectors. You can check the motor full load amperage (if it will run on high speed) to see if it is pulling more than 20 amps. If so, and the motor is failing, it will eventually take the blower control module with it! Check these things first and if you need help finding a new ACDelco control module at ½ the price of the dealer, send me a PM for more info. Good Luck!

According with the GM Service Manual and confirmed by GM dealer, there is a Blower Control Module (GM Part number 52470337 or AC 15-8684) AND a Blower Motor Resistor (GM part number 19113258 /discontinued) or AC 15-D1119) in my car equipped with the CJ2 option. I have the schematics and even the picture of both parts and their precise locations under the relays in the engine compartment. If what you say is true about CJ2 option, GM parts and service department are really in the fog (It would not be the only time). This is precisely why I do some research first. I DON'T want to pay to have them learn how my car is made.

I agree with you that a failing motor will eventually fry the control module. This is precisely why I'm trying to PREVENT total failure. I am equipped to check the 20 Amp, this is an excellent suggestion. I found price and availability for all parts from AC Delco or 3rd party, GM dealer parts are discontinued or twice the price. It is too late for me to check it out tonight, but I will definitely look at it tomorrow night. Since my Blower motor usually works fine even at low speed, it is not the prime suspect, but with the 20 Amp max idea, I will know for sure. There is something that prevent the variable voltage to reliably get to it.

Thanks !

Martin

Some of these cars come equipped with "auto climate control" with dual (driver/passenger) control, and others come with single display, or manual control, hence the reference to both the control module and relay/resistor motor control. I have never seen one equipped both ways, it would be fruitless! It could be possible that you have the “delayed module kit” (Delayed blower control) Part # 15-5876 It looks like this:


http://img232.imageshack.us/img232/6682/delayresistorvb6.gif



BTW, the module listed for your car: 97 98 99 Pontiac Bonneville Buick Lesabre Olds (97 98 99) Regency Delta 88 LSS AC A/C Heater Heat Blower Control Module
Delco Part # 15-8684 OEM GM ACDelco
GM # 52470337

Thanks for the precisions, I suppose it is impossible for parts and service department to know all possible variations, but I provided my VIN and this is the information they gave me which matched my own service manual... I can't conceive a company to keep even their own employees in the fog like this ! I'm not about to write them a blank check... Here's why:

When I purchased this car (used) the engine intake cover was cracked and leaked antifreeze in the engine head. My local GM dealer estimated the cost of parts and labour to nearly 700$. This notorious defect is not covered by a recall by GM in Canada. I found a new redesigned spare part on Ebay and got it installed by my local mechanic for 120$ (part, shipping, custom fees, taxes & labour included). I love this car and I still beleive the V6 3800 engine is excellent. This was worth the trouble, but such adventures really broke any bound of trust there was between me and GM dealers.

I finally replaced the control module and the blowing motor at the same time. Control module showed some corrosion on the heat sink attached component. The blower motor was fine, but the blower motor cover (made of some hard rubber or rubber like plastic) was damaged from exhaust heat and the cooling pipe running from the firewall to the blower motor no longer connected tightly: the blower cover end was falling into pieces around the bottom, where the pipe is connected and where exhaust heat is the worst. I was able to make a temporary fix, but I will eventually have to get a new cover. Up here in Canada it costs over 60$. I doubt it is worth trying to get a good one from scrap yard. I suppose this open entry for dirt and humidity combined to the absence of cooling air would have cause the engine to fail prematurely.

So far, so good, the system is back to normal, regardless of outdoor temperature. Thanks to all for your kind advises

Martin