A/C control module....

[James Waters]

Can anyone give me some advice I've had my 2004 Yukon in the shop three times in the last 3 weeks ..the AC would begin blowing hot air out of one or more of the vents. so they put one blend door actuator in and have replaced the control head three times ..it has now began to not come on at all sometimes.. and I have found that I can remove the fuse and put it right back in and it will come on... although it is not blowing hot air out now when it is working.. the temperature is always very cold no matter weather you set it on 60 or 80 degrees as long as the AC emblem is on it is ice cold.i can live with that.. also when the car sets for 3 days or longer it will not start without a boost and the battery is good... I never had a problem with this car not starting until I again this work on the AC system.. I am on the verge of selling this car because of this problem although I love my yukon..the mechanics are scratching their heads and they are very good mechanics... I don't feel that they could replace three control heads with brand new ones and they all be bad... the last one was a different brand...

 

[Doubeleive]

doesn't make any sense that it would start with a boost yet the battery is good?? I would question that highly

I would have both the battery and alternator tested that could be the root of your problem, or you have a bad parasitic drain.

 

[James Waters]

doesn't make any sense that it would start with a boost yet the battery is good?? I would question that highly

I would have both the battery and alternator tested that could be the root of your problem, or you have a bad parasitic drain.

 

[James Waters]

Thanks I will have those checked again.. I must ask what is a parasitic drain?

 

[Doubeleive]

a parasitic drain would be like leaving the headlights on or the radio on, only it's something else shorted or not working properly and causing the battery to go dead. for instance a bad blower motor resistor could be shorted and cause the heater fan to keep running and possibly drain the battery, there are ways to check for this with a simple multi meter as a next step if the battery and alternator check out good

 

[RET423]

If the A/C always blows cold out of some vents but not others you have a blend door sticking, the actuators are not the only thing that cause blend doors to move insufficiently; it could be something fell down into the diverter box (like a pen from the dash) that prevents full travel of the blend door.

Many batteries that "test good" after charging will test bad after they sit awhile, early cell failure does this all the time. If you disconnect the battery and charge it, then leave it disconnected for a day before testing it; you will often find it tests bad. This test can avoid a lot of unnecessary "short chasing", if it test good after being disconnected then you know some component on the vehicle is draining the battery when it is not in use.