HVAC Problem

[eaglepilot]

I have a 05 Vette with 2 issues in the HVAC system:

Issue 1 - In the manual mode, the fan speed will get stuck when manually adjusting the fan above 5 bars on the display....once 6 bars is selected the fan remains on high and cannot be adjusted neither higher nor lower. The only way to reduce the fan speed is to turn the HVAC system off, however, once you turn it back on, the fan returns to the high speed even with the display indicating 1 bar. Once you turn the ignition off and restart the engine, then the fan control is restored and works just fine as long as you do not select a fan speed higher than 5 bars. In Auto Mode, anything works fine until you rise the temp high enough to force the fan speed to 5 bars, then the fan speed is stuck on high and unable to lower the fan speed by lowering the temp or when manually selecting low fan speed (1 bar).

Issue 2 - The air control mode appears to be inop, air is coming out the defrost and forward vents and unable to change the flow with the mode button or by cycling the defrost button. As I change the mode button, the digital display changes modes, however, none of the vents (defrost, forward, or floor) change any air flow at all, plus I can not hear any actuators trying to move. Hard to believe all the actuators are broken.

The temp control works fine in Auto and Manual and the outside air vent button appears to work also.

I check for fault codes and have none...I also checked all the HVAC fuses, which were good....plus I disconnected the battery for 10 minutes in an attempt temp to reset the actuators and/or the HVAC system...still have the same 2 issues.

Any clues on what to try next....any procedure to calibrate the actuator doors or to reset the fan control. Thanks

[c4c5specialist]

HI there,

There must be something there.

What did you use to scan fault codes with??

Many aftermarket scan tools cannot scan the HVAC control module, nor can they see the data.

I would be looking to see what the commands are within the control module.

Then, using the Tech 2, perform the commands instead of using the control head.

Allthebest, c4c5

[eaglepilot]

I only have an Actron OBD II (CP 9175) and used it to reset a P0430 (Catalyst Efficiency below threshold Bank 2) code, not sure what caused it, but it has not returned. Can this code checker pull HVAC codes or will I be forced to take it to the Dealer?

[c4c5specialist]

HI there,

That will only do powertrain failure codes and cannot scan any other computer module within the vehicle.

Yes, it will have to go to the dealership.

Or someone with a Tech 2.

Allthebest, c4c5