Quote:
Originally Posted by 63burban4x4
I'll be very interested in the repair required on your A/C problem.....my '04 Silverado 2500 HD has had the same issue for several years now. Suddenly blowing blistering hot air from the driver's side only, pass side is fine. For a while it would, like you said, reset on restarting, and be fine, but eventually it did it MOST of the time. It's been diagnosed as: a) computer problem; reprogramed, (a bunch of times!) only lasted a short while. b) blend door actuator; $$$, only fixed it for a while. c: bad BCM; replaced (with a used BCM) stopped doing it for a while, (meanwhile that caused OTHER problems: Air Bag warning light, still not fixed, locked security code in radio requiring a $95 reset of code BY DEALER ONLY) and NOW AFTER A COUPLE OF MONTHS, THE DRIVER'S SIDE A/C is intermitently blowing HOT AGAIN!!!!!!!!!!!!!!!!) This is driving me crazy, and I have had 2 different shops try to fix this. Both have pretty decent mechanics, and it's driving them crazy too!! Worst thing is, you cannot close the center A/C vent in the dash, so you have to suffer.....the only way I've been able to deal with it, is to make the wife drive, so I can sit on the cool side   -Ed
oh, and it only NOW has 91,000 miles, started this crap at 60-70,000 miles! |
To fix this you have to know how it works! Most mechanic's are lazy, SOLEY dependant on a scan tool to tell them whats wrong....Though a Tech II is mandatory to retrieve codes from the HVAC control head.
Put the original BCM back in....It should have never been replaced.
If they replaced the Blend door actuator......I hope it was The Left Temperature Blend Door Actuator?
1. Gain access to the left air temperature motor for circuit testing. There are 5 wires at the motor.
2. The Brown wire is ignition power.
3. The Black wire is a ground at all times.
4. The Gray wire carries a 5-volt reference from the control head to the temperature motor.
5. The Light Blue wire is the feedback circuit to the control head and should measure between about 1 volt (cold) and 4 volts (hot). This feedback circuit operates similarly to a Throttle Position Sensor (TPS).
6. The Dark Blue wire is the motor control circuit sent from the control head.
7. When the control head sends out 5 volts on this wire, the motor moves towards cold.
8. When the control head sends out 0 volts, the motor moves towards hot.
9. When the temperature motor reaches the correct position (as measured by the feedback voltage on the Light Blue wire), the control head sends out 2.5 volts. This voltage signals the temperature motor to STOP and hold its present position.
10. Check for correct operation of these voltages.
11. In some cases, the air temperature door does not fit correctly in the plenum and will cause the air temperature motor to travel too far. This will cause the control head to become confused and operate erratically.