Calibration mod for HVAC brain?

[irving washington]

I don't like the way the OEM ECU auto temp control works. If I set it one click above the coldest temp - it is almost always too warm in the car. When I set it to the blue mark (coldest) - it is usually too cold. I tried to "fool" the system by using the little slider switch on the top of the ECU to shift the calibration to cooler by a few degrees. This did not do enough. I am thinking of cutting into the wiring of the temp sensing thermister beside the ashtray and adding ohms or reducing them (shunt resistor) to further fool the system. This is pretty crude......so has anyone else already tried to do stuff like this .....and has ideas to share?
MOTE - the ECU is working fine other wise - fully tested and refurbed and all the air flow doors work fine.

 

[john@johnhudakracing]

I use the Motec HVAC controller with the Bosch infrared sensors to get my car into the goldielox zone. It allows you to fine tune your temp down to the thousandth of a degree, and monitor it in real-time via telemetry. :wink:

 

[Briank]

I gusee you could mess with the sensor inputs to the CCU to get it to operate correctly but most likelly you have something that is not right in the system. Most likelly is the CCU it self has a problem or one of the sensors is disconnected.

What year is your car?

Did I do the repair on your CCU?

Have you run the test procedure and have no faults indicated?

 

[LJSB]

Check the fan at the abient air sensor located in the center console by the hand brake. It's the one behind that little vent.

It is common for these it to have over time sucked in enough lint to hinder the sensor from correctly reading the cabin air temp.

I have pulled some impressive balls of lint out of them and when working on the console I always check and clean this out. HTH.

 

[Cozmo]

Check the fan at the abient air sensor located in the center console by the hand brake. It's the one behind that little vent.

I've always wondered what was behind that.. Thanks for solving the mystery for me :wink: