2003 Z06

I went for a drive this morning and the a/c blower motor stopped working. I did a search and have done the following :

1) The a/c is turning on, the compressor clutch is engaging and engine idle increases slightly.
2) The fan indicator on the dual zone display works normally, goes up an down with the arrows, but the blower never turns on. I tried all zones, no luck.
3) I checked the blower motor and all HVAC fuses, all are good
4) I pulled the blower motor, it runs with 12v connected directly to it
5) I pulled the control module. I didn’t see any obvious signs of damage or failure on the circuit board. **I get a consistent 13.9-14v coming out of this with the car running regardless of fan setting**
6) I pulled the HVAC control panel and saw no sign of damage or failure on the circuit board.
7) I checked for DTC codes, there were some codes in the LDCM and RDCM, but all were old (h) and not a/c related. HVAC shows no codes.

When I reassembled the control module and blower and started the car, the blower came on for a couple seconds then cut off again.

Should the voltage coming out of the control module vary with selected fan speed? But with steady 14v, I’d think it would be stuck on high?

After reviewing dozens of related threads, I’m leaning towards replacing the control module. Any other ideas?

***UPDATE***. I changed the control module, I still get 13.86V to the motor from the control module, but it still doesn’t run.

 

try starting it with a tech 2

 

You did some good testing,...here is some additional info for further testing to find the failure.
Blower Motor Inoperative

Important: The blower motor control processor and HVAC control module connectors must be connected to correctly perform the test.
1. Backprobe and measure the voltage from the blower speed control circuit at the HVAC control module to a good ground.
2. Gradually adjust the blower motor switch from the minimum speed position to the maximum speed position.
Does the measured voltage continuously decrease between the specified values?
5.0 V OFF 1.0 V ON

1. Turn the ignition OFF.
2. Disconnect the HVAC control module.
3. Turn ON the ignition, with the engine OFF.
4. Measure the voltage from the blower speed control circuit of the HVAC control module to a good ground. Does the voltage measure near the specified value? 5.0 V

Test the blower speed control circuit of the HVAC control module for an open, short to ground or short to voltage.

Schematic and connector end views for pin locations.


2003 car schematic

HVAC connector


blower/

Ground 202 and splice 202


Ground 202 Splice 202

Post up your findings and or fix.
Cheers,
Goose

 

I replaced the control module and tested, didn’t work.

I installed a new blower motor with the new control module, and it works! The old motor ran with 12v directly to it, but not installed in the car.

My next step was going to be start chasing wires and grounds.

I chalking this up to mouse nest. I found a little nest debris in the fan and ducting up there. I have the cowl off to clean it pout and spray Lysol into the ducts.

Thanks everyone who posted info over the years, it got me troubleshooting early and in the right places.