a/c blower motor not working
Thread Starter
Le Mans Master
Joined: Jan 2006
Posts: 5,695
Likes: 2
a/c blower motor not working
1991 ZR-1:
450 miles up the Nevada desert with no HVAC fan...ugh! Still gotta go back through NV or Death Valley..Aaarrrrrgh!!!
I pulled all 3 panel fuses to rest and nothing worked. I looked for codes in the fan control window...no codes. The manual says there's an UNDERHOOD fuse to protect the fan (blower) motor.
WHERE is it???????????
450 miles up the Nevada desert with no HVAC fan...ugh! Still gotta go back through NV or Death Valley..Aaarrrrrgh!!!
I pulled all 3 panel fuses to rest and nothing worked. I looked for codes in the fan control window...no codes. The manual says there's an UNDERHOOD fuse to protect the fan (blower) motor.
WHERE is it???????????
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
You have to unbolt the black plastic radiator fill tank and move it out of the way. Mounted on the firewall is what looks like a black plastic miniature relay holder with two purple wires going to it. The fuse is inside the holder.
If the fuse were blown, the blower motor would continue to run even with the ignition off.
I'm looking at the schematic from a 90 service manual so the color code of the wires may be different from that of a 91.
The HVAC Programmer provides a DC input voltage on the Dark Green Yellow wire to the Blower Control Module.
The Blower Control Module outputs a voltage on the Purple wire which drives the Blower Motor.
The Blower Control Module is located inside the Evaporator housing. If you look on top of the evaporator housing on the engine side you'll see two electrical connectors that plug into the Blower Control Module. The Module is held in by some small bolts. Look at the two connectors for any burn marks.
Turn the ignition on, turn the fan on, with a voltmeter measure the voltage on the Yellow/Green wire which will vary from 2.5 to 7 volts depending on fan speed setting.
Output Voltage of the Blower Motor Control Module (Purple wire) goes to the Blower Motor and will vary from 4 to 12 volts.
Red wire is 12 volts to power the Blower Module and is hot at all times.
Black wire is ground.
To test the Blower motor itself, unplug the two pin connector and apply 12 volts direct to the motor.
If the fuse were blown, the blower motor would continue to run even with the ignition off.
I'm looking at the schematic from a 90 service manual so the color code of the wires may be different from that of a 91.
The HVAC Programmer provides a DC input voltage on the Dark Green Yellow wire to the Blower Control Module.
The Blower Control Module outputs a voltage on the Purple wire which drives the Blower Motor.
The Blower Control Module is located inside the Evaporator housing. If you look on top of the evaporator housing on the engine side you'll see two electrical connectors that plug into the Blower Control Module. The Module is held in by some small bolts. Look at the two connectors for any burn marks.
Turn the ignition on, turn the fan on, with a voltmeter measure the voltage on the Yellow/Green wire which will vary from 2.5 to 7 volts depending on fan speed setting.
Output Voltage of the Blower Motor Control Module (Purple wire) goes to the Blower Motor and will vary from 4 to 12 volts.
Red wire is 12 volts to power the Blower Module and is hot at all times.
Black wire is ground.
To test the Blower motor itself, unplug the two pin connector and apply 12 volts direct to the motor.
Last edited by Hooked on Vettes; Mar 22, 2008 at 06:49 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Sounds like the Blower Module, but just make sure the harness hasn't opened at the Motor. Leads are crimped and these motors can draw enough amps (particularly as they age) to heat up the power side causing the wire to melt.
You can also check Module Power - red - and though I don't know the ZR1 harness, that's usually battery - always hot.
'84 is a different animal with Manual Controls. You should start a new post, but check for a faulty relay or a short to voltage on the Power side (which should be red/black - not purple - for this Year).
You can also check Module Power - red - and though I don't know the ZR1 harness, that's usually battery - always hot.
'84 is a different animal with Manual Controls. You should start a new post, but check for a faulty relay or a short to voltage on the Power side (which should be red/black - not purple - for this Year).
