Automotive Air Conditioning Information Forum

I am having the same problem with my 2004 GMC Yukon. Bought used 4 days ago. I am in South (Mississippi). Warm climate. I test drove vehicle on warm day (80 degree ambient temp) before purchasing and A/C worked fine. Blew cold. Yesterday temps dropped into 40s in morning. Ran car with heat. As temps in day rose back into 70s, passenger side a/c kicked and blew cold, but driver side continued to blow hot air. Have a dual driver/passenger system. I can not see how this would be a leak or compressor issue as with the original post to this forum thread as the passenger side is blowing cold. If there is a leak or compressor issue wouldn't the passenger side also blow hot? Compressor is turning on and off. Have not had time to perform any pressure readings or other diagnostics. Will try to get to it this weekend. When passenger is blowing cold and driver is blowing hot, seems to me their must be a control switch or sensor failing that is not telling the system to blow cold on the driver side. Is there such a mechanism or switch that could go out? Do these things work with such sensors or switches? What is a solar sensor?

What is the blender door?

Solved

Oh yeah...one more thing. May be coincidence or unrelated, but battrry was dead when got up this morning to start truck (Yukon). Jump started. At time, ambient temps were cold..high30s/low 40s. Heater worked and running. Drove to local Napa and bought new battery. Replaced battery. By then temps were rising. Hour later temps were approaching 70 and driverside would not blow cool air. Passenger side blows cool and works fine. My question is...could disconnecting and changing out the battery, have effected my a/c? Does somethibg in the car's computer have to reset when there is a loss of battery power in order for the a/c to run properly?

Upon further online search, found this Technical Bulletin (carjunky.com) that seems to point to the "blend door" as the likely culprit. This appears to be a common problem with GM trucks and cars. My guess is that when the battery died, the car's computer some how screwed up the actuator settings (or as the bulletin suggests...possibly moving the actuator to a default position). What do you think? If so, how do I fix it? Can it be reset with a code reader at a auto parts store (Autozone, etc.) or will I have to take it to a service department with more equipment? Why does this not correct itself? After a power loss (dead battery) and once power is restored, shouldn't the computer "reboot" or reset itself and restore all previius settings? In another forum, someone suggested "Place the ignition switch to the OFF position.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds .
Install the HVAC/ECAS fuse.
Start the vehicle.
wait @1minute !! for the HVAC control module to self-calibrate. Then try system again." What do you think? Where do I find the HVAC/ECAS fuse?

Bulletin No.: 06-01-38-003

Date: April 27, 2006

TECHNICAL

Subject:
Intermittent Ticking Noise from I/P, Poor A/C Performance, HVAC DTCs B0229, B0414, B0424, B3770 (Reprogram HVAC Control Module)

Models:
2004-2006 Cadillac Escalade Models
2004-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2004-2006 GMC Sierra Models, Yukon Models

with Air Conditioning (RPOs CJ2, CJ3)

Condition

Some customers may comment on one or more of the following concerns:

^ Intermittent ticking/clicking noise from the instrument panel.

^ Recirculation mode does not work or Air Conditioning (A/C) system performance is poor during high ambient temperatures.

^ Unable to control the driver side temperature.

^ Unable to control the passenger side temperature.

^ Unable to change the front system modes.

Cause

This condition may be caused by the Heating, Ventilation and Air Conditioning (HVAC) actuators that may hunt for the correct commanded position. This cycling may cause a clicking or ticking noise.

An overtravel of the HVAC system control doors may cause one or more of the concerns listed above. If an overtravel occurs, a Diagnostic Trouble Code (DTC) will be set, and the door will go to a preset default position. When a system door defaults, that door will stay at the default position until the DTC is cleared. After the DTC is cleared, the door will operate properly until the overtravel condition re-occurs.