'96 LeSabre climate control

[Alex_V]

Trying to get my Buick's climate control working again. It's Limited trim with automatic temp. control. The fan works when hot-wired, but when hooked up through the harness none of the CC modes or fan speeds get the fan to come on. All the blend doors, etc., work correctly. The control panel (the part with the LCD and buttons) has been tested by an outfit that remans them and was good, so I'm down to the blower module and HVAC programmer. Going through testing procedures for the blower module, all voltage inputs to it test correct except that I have a constant 9V on the signal wire from the programmer, regardless of fan speed setting. What next?

Thanks!

 

[Trav]

If you have constant 9V and its supposed to vary with blower speed setting I would suspect the programmer. I have no idea but it seems logical from your description.
Is the line that has 9v supposed to vary between x-y with fan speed setting?

 

[Alex_V]

That's seems logical, Trav. And yes, IIRC it should read 2-10 volts depending on fan speed. I was hoping someone has more specific knowledge of the problem or equipment used here to lend more edumication to the troubleshooting.

 

[eljefino]

The 9V could be your DVOM reading a pulse-width modulated output and ignoring the lows. Try a brake light bulb-- that should increase with brightness per fan speed and put enough load on it to really test it.

 

[Alex_V]

Good call. I'll do that.

 

[mk378]

Examine the plug on the blower module for any sign of melting or burning. If it has overheated, replace both the module and the plug.

 

[Alex_V]

No signs of that.

 

[Alex_V]

Tried running a test light (side-marker light harness adapted to the task) off the variable voltage from the HVAC programmer to the blower module, and can still get a 9VDC reading with my voltmeter, but when the test light is hooked up it won't put out any voltage. Tried it several times, both running and just with the key on, to no avail. A short?

 

[zzyzzx]

I'm thinking open circuit.

 

[Merkava_4]

Here's a link to a parts manufacturer that that has a free database of electrical drawings. You just gotta enter in your personal information before they let you use their database.

http://bbbind.com/tech_database.html