Pontiac Repair: Heat, climate control systems, pontiac bonneville

Question
QUESTION: Hi Todd,

1997 Pontiac Bonneville SSE 3800 non-super charge. It has the auto temp control unit. The HVAC system blows cold air no matter what the setting is unless I have driven the car for a while and then play with all of the settings(temp, fan speed, mode, etc.) then sometimes it starts to work. It was cooler even during 80 degree days, although it was quicker to get the heat to come on. I changed the thermostat early on, and that wasn't it. Also, the radiator cooling fans do not come on (may not be related). I thought maybe the heater core but once I get the heat to come on, it's very warm. I checked for blown fuses to no avail. I'm guessing it may be a module, vacuum? Any assistance would be extremely appreciated. Thanks in advance, Jeff.

ANSWER: Hi Jeff:

Well with thes older auto climate control systems were VERY hard to figure out what was wrong with them. If the control head doesn't flash "blink" the temp when it's on they there is not a hard fault in the system. It's much easier to find the problem when there is an actual part that has failed. in this case I'm thinking you have a temp sesnor in the car that is not giving the control module the right information and that is why you are not getting the temp you have selected on the control head. With out the aid of a scan tool ther is nothing that you are going to be able to do with this your self. If it had a temp acatuator that failed it would never change temps at all so that's not it.  This car is all electric controlled no vacuum actuators. As for the engine cooling fan the engine may not be hot enough for the fans to come on. if the a/c still works on this car turn on the a/c and let the car run for a few minutes if the outside temp is warm enough and the a/c is running and working correctly the fan(s) should come on.


---------- FOLLOW-UP ----------

QUESTION: Now that you mention it, the temp light does blink. So what does this mean? Someone I know has a code reader, is this the same as a scan tool? As far as the cooling fans go, I think I'm going to bypass it with a toggle switch or a bimetal thermostat. What do you think? Thanks for all of your time and help!

Answer
do not bypass the cooling fans if you for get to turn them on you'll cook the engine of if the theromstatic device you put in fails the same thing will happen. Have the issue looked and and fixed it could be something really easy like a relay,fuse that blew from a nad motor etc.. As for the heater control You need more than a code reader you need a scan tool that can read data. A factory scan tool or a GOOD scan tool from like snap-on or Mac and even those are hit and miss on heater control data. Like I sated before the ealrier models were hard to repair and a bit arcaic. Again good luck :)