I posted this question on the tech/general engine board and got some help. I'm still having problems with the HVAC, so I thought that I would post here as well, as the problem may be an unforeseen electrical problem.

When I turn on the a/c, heater, defroster, etc. no air comes out of the vents. I checked the fuse. I already replaced the blower motor. I had to buy a new cage(fan) because the stock one didn't fit on the new blower. I also replaced the a/c compressor control relay. I looked at the resisters and they look O.K.. Those are the things that look like the inside of a light bulb, right? How can you tell if the resistors are bad? I pulled out the HVAC control panel(as much as the wires would let me). The wires look fine. I pulled out the connectors that go to the blower speed **** and the selector(max,norm,bi,vent,heat,etc) and some of the little metal prongs that go into the connectors look a little rusty. Someone told me that the problem could be the brown wire that goes to the "mode" selector. Something about its connection being nothing but a pile of ashes(or something to that effect). I looked at the brown wire and couldn't follow it to its origin, because it becomes to hard to reach.

When I turn on the a/c, the compressor clutch engages and disengages; the radiator electric fan kicks on, but that's about it. I don't have a multitester or testlight.

Sorry for the long post. Thanks in advance for any suggestions you can give.

 

i had a similar problem, my air wouldn't come out the vents or defroster, just the floor. i bought a new control off ebay for $5 and that took care of that.

 

You said no air comes out, not that the blower wasn't working. There is a difference, which is it? The blower could be working but no air coming out due to some type of problem in the ducting/damper. If the blower motor is not actually working in one or more speeds you will need to do some trouble shooting which will require a voltmeter or testlight. A testlight will work fine and will only cost a couple of bucks at WalMart or AutoZone. You can also get a multimeter for under $20, but a testlight would probably be the best choice for someone unexperienced in their use. Here's how to test the electrical circuits for the blower. Note that the ground lead of the testlight must be clipped to bare metal that actually connects to the car body. The negative battery terminal or an engine bolt will work good. Test the testlight on the battery or a fuse to make sure your connection/testlight is good.

Power for the lower speeds go thru the selector switch, then thru the resistor assy. before going to the motor. As for hi speed, power for it goes thru the selector switch then to a relay, then to the motor.

The resistor assy. and relay are mounted near the blower motor. You can do most of the testing at the resistor assy.. Test for 12v on these wires with the indicated speed selected:

lo - yellow
m1 - tan
m2 - lt. blue
hi - purple

No power on yellow, tan, or blue would indicate a bad selector switch.

The purple wire should be hot in all positions but the voltage will be lower (testlight bulb dimmer) for all but hi. If no power in lo, m1, or m2, the resistor assy is bad.

Check the orange, purple, and red wires on the relay. They should be hot when hi selected. Red should be hot at all times. If no power on orange, the selector switch is bad. No power on red would indicate a blown fusable link, but you would have other problems as well. No power on purple, but others hot, would indicate a bad hi speed relay.

 

Thanks for the info guys. I just bought a test light; and I have one question. Should the engine be running when I test the circuits or should I just put the key in the "on" position?

If the problem turns out to be the selector switch, where is it located? Is it mounted on the control panel?

 

just have it in the ON position

------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

I finished testing the circuits. I ran through the tests with the engine running(sorry breathment, I didn't see your post until after I checked the circuits) and the a/c on the "norm" position. Here are the results:

RESISTOR ASSY: (I pulled the grey-colored connector and tested the wires.)
Low(yellow)-No Power
m1(tan)-No Power
m2(lt. blue)-No Power
Hi(purple)-No Power
Purple(low)-No Power
Purple(m1)-No Power
Purple(m2)-No Power

RELAY:
Orange(Hi)-No Power
Purple(Hi)-No Power
Red(low)-Power
Red(m1)-Power
Red(m2)-Power
Red(Hi)-Power

I figure that I have a bad Selector Switch and maybe a bad Resistor Assembly. Do you all agree?

[This message has been edited by coach (edited October 07, 2001).]

 

It looks like you will have to pull your A/C control loose from the dash and do some more testing to determine if the problem is the blower switch or A/C mode selector, or fuse.

Turn the key to the on position. Set the A/C mode selector to any position besides off (max, norm, etc.). You should now have power on the Brown/White wire on the blower switch. If you do have power (+12v) then the blower switch is bad. If you do have power on Brown/White, check the Brown wire on the mode selector. If you have power there, the problem is the mode selector. If no power, the problem is the Heater-A/C fuse or wiring between the fuse and mode selector.

 

Thanks IROC&ROLL. Well, today I replaced the Blower Switch and it still didn't work. So, I put the old switch back on. With the new switch, I could only use one of the two mounting bolts; but it still plugged in.

I then checked where the fuse inserts, with the test light. At first, I wasn't getting any power; then after checking it again, I was getting power. I put the fuse back in and turned the engine and a/c on; the blower motor kicked on and I smelled something electrical for a second or two. The a/c worked!!! The a/c worked in all speeds .

The blower sounded abnormal; there was a ticking sound that got faster as I increased blower speed. I then took the blower motor out to adjust the cage(fan); I thought that the ticking I was hearing was the cage rubbing something. I hooked the old blower motor up just to see if it would run; it didn't. So, I put the new motor back in. I tried the a/c again and it didn't work . There's power going to the fuse(there were a couple of times when the fuse wouldn't show power).

When I had the control panel out, I removed the connector for the mode selector. The prongs for the mode selector are a little rusty. I couldn't test the wires, because I didn't know which ones to check. So thanks for telling me which ones. I'll check tomorrow. How do you check behind the fuse panel? Do you have to unbolt something or flip it a certain way? Thanks for all your help and wisdom.

 

The a/c works again! Thank you guys for all of your help. Long story short: new blower motor, new relay, new blower switch, and new mode selector switch.

The blower motor makes a ticking sound that increases with blower speed. I think that it may just be the metal fan(cage); the old one used to be plastic. Do new motors make that sound? I didn't see anything that the fan could rub.

After all of the frustration, there's nothing quite like getting the job done. I've learned a lot. Thanks for all your help and advice; it was greatly appreciated