How do you calibrate a ac/heater control unit

Very common problem. Actuators need to be re-calibrated. Disconnect battery with ac controller off. And reconnect after 5 min. If not your going to need a modis to recalibrate.

I found these instructions when my heater suddenly stopped working. Start car, while car is parked turn temperature to 75. Hold down the floor, defrost/floor and the defrost buttons. Wait til the temp light starts blinking, release. It will blink for a while and either recalibrate and be fine like mine or you could get 1 of 16 different trouble codes. Hope this helps. ;p ~Redmoon

Hi Kutis, Could you give us more information? I believe your referring to the cabin climate heat control. What belt did 'they' change? if was the belt for the AC? If it was I believe you may have the Air Conditioning running on cooling instead of heating? Look at the dash climate controls and you will see one for the AC control. If it is illuminated press the button to disengage it and the heat should work. If it was a different belt we need to know which one was replaced? We also need to know what else was done? Regards John

you have taken the calibration out of sink. you will now have to remove battery power again for about 5 minutes. after this time reconnect the battery. then turn key to on position for 3 minutes but do not touch the heater control or temperature controls. This should allow the heater and ac system to recalibrate. once the 3 minutes is up turn key off and then back on and start truck.. Try your controls again and see what happens. if no change then dealer will have to reprogram the heater control calibration for you.

Hi, it's called the blower motor cooling hose.
Thanks for using FixYa.

(copied and reposted from another person)....I had the same problem you do. What has most likely happened is that the Heater-a/c unit needs to be recalibrated. Here are the steps to do it.
With the engine running and fully warmed up, A/C has to be turned off for at least 5 minutes [don't turn it on at all] and transmission in Park do the following
1. Set the temp control all the way to cold
2. Set the mode selector to Vent [blowing in your face] so air blows out of the dash panel outlets.
3. Hold down the rear washer button [top left] and the rear wiper button [bottom left] simultaineously for about 5 seconds until most all of the heater and ac panel lights blink and then release both buttons.
6. At this point the system should go into a self calibration test which can take up to 60 seconds. While it is calibrating various control panel switch lights will blink as it goes through it's tests.
7. When the system is done calibrating then just the rear wiper light should be flashing and you can exit the test by turning off the vehicle. Wait about 10 seconds and restart the engine and it should be fine. If both the rear wiper and intermittent light are both still flashing after the calibration then there is most likely a problem with the system that will need more diagnosing. This sometimes happens with battery replacement. It sometimes takes a couple of tries to calibrate so don't give up if it doesn't work the first time.

What has most likely happened is that the Heater-a/c unit needs to be recalibrated and here are the steps to do so.
With the engine running and fully warmed up, A/C has to be turned off for at least 5 minutes [don't turn it on at all] and transmission in Park do the following
1. Set the temp control all the way to cold
2. Set the mode selector to Vent so air blows out of the dash panel outlets.
3. Hold down the rear washer button and the rear wiper buttons simultaineously for about 5 seconds until most all of the heater and ac panel lights blink and then release both buttons
6. At this point the system should go into a self calibration test which can take up to 60 seconds. While it is calibrating various control panel switch lights will blink as it goes through it's tests.
7. When the system is done calibrating then just the rear wiper light should be flashing and you can exit the test by turning off the vehicle. Wait about 10 seconds and restart the engine and it should be fine. If both the rear wiper and intermittent light are both still flashing after the calibration then there is most likely a problem with the system that will need more diagnosing. I see this fairly often with battery replacements so I think you'll be ok. It sometimes takes a couple of tries to calibrate so don't give up if it doesn't work the first time. Good luck, hope this helps!

Either needs recalibration, or control unit. Press the wiper and wiper washer buttons simultaniously, and wait for them to start blinking one then the other. Then press the recirc button and the washer button same as above. Should be calibrated after this.

This means there are body codes stored in the computer.

I believe you have another problem, because the radio will keep the calibration of the radio as long as it stays in your van. it will only lock if radio is swaped with another pontiac radio. to unlock it you will need a GM tech II to recalibrate the unit.