I tried turning on my front defroster today and nothing happened. The fan isn't blowing any air at all; however, when I switch from vent to defrost and so forth, I can still hear that it is still switching over, just no air is coming out. I checked the fuses and they are fine; I also pulled out the AC/Heater controls to make sure everything is plugged in...anyone have any other ideas what to check? Is there a relay and where would it be located?

Thanks,
Joe

 

https://www.thirdgen.org/forums/cool...er-heater.html

JamesC

 

I replaced the blower motor yesterday...still doesn't work. Should I try replacing the relay next?

Joe

 

Yes.

JamesC

 

Well, it wasn't the relay either....guess I'll try replacing the switch next...

Joe

 

The relay is only used for "HI" fan speed. Make sure the fan motor ground wire connections are good.

 

The fan motor ground wire is the black wire that plugs into the metal tab on the fan housing? If so, then that's good.

Also, should the fan work when the car is not on, but the key is in the accessory position?

Thanks,
Joe

 

Update: I STILL can't get the fan to come on. So far, I've replaced the blower motor, blower relay, fuse and fan switch. STILL NOTHING! This might not help, but here's a pic of my engine compartment near the blower motor:



Thanks,
Joe

 

The relay in your pic looks odd. Check the one in the following pic:

https://www.thirdgen.org/forums/cool...er-heater.html

JamesC

 

That's the relay I just replaced....the original looked more like it does in that other picture, except it's rectangular shaped. My car is an 84 and that other pic looks like it may be a newer thirdgen? Maybe that's why it's different.

Thanks,
Joe

 

The relay in my 85 IROC looks exactly like the one in the link I posted. Any possibility your replacement is incorrect?

JamesC

 

No, it's definately the correct one. The one that was in there before looked identical to the new one, except it had a black plastic cover, but the pins and the size and shape were the same. When the blower did work (last time I used it was last year) I had the original relay in it, so that's definately not it.

Joe

 

Deleted

 

Check the A/C fuse.

If that's good, pull your A/C control head out of your dash. Look at the "mode" switch; the Off/AC/Max/BiLevel/ etc. one. You'll see some wires that go to the fan switch, a green wire that goes one way, and a brown wire that goes up and to the left. Follow that brown wire about a foot or so; you'll come to a connector of unbelievably stupid design. It is the power feed to the entire HVAC system. Attempt to decouple it. Most likely, it will either be melted into a solid blob of crispy crud, or it will fall to dust because it has burnt to ashes, like everybody else's.

Cut both halves of its remains off, and replace it with a pair of the BIG FAT YELLOW slide terminals, the insulated kind.

I can think, off the top of my head, of at least 6 late 70s and 80s GM cars of my own or my immediate family's, that I've had to change that connector out.
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That's amusing.... you've already got it out!!!

Don't worry about the number of wires or any of that just yet, start with that connector I told you about. It's in that brown with white stripe wire.

 

I know exactly which connector you are talking about. I tried (not very hard) to seperate it and it wouldn't budge. The outside of the connector didnt look melted but I'll try again to get it apart to see what we've got going on there.

 

Maybe these will help you. Out of 84 camaro shop manual should be the same or close. I had the same problem mine was the relay but agian hopefully this helps

 

Is this the brown wire with the "stupidly designed" connector you are talking about? (I pulled the female end out behind the console so I could get a better look at it)



If so, I cleaned the contacts and checked for melting...all looked good so I put it back together and still nothing worked. Next idea?

Joe

P.S. AC fuse is fine also...I even replaced it with a new one, just in case. Still nothing

I don't think I mentioned this, but I put a 350 in this car last summer. The last time theese controls worked was before I put the new engine in. Is it possible that something happened then? Perhaps with the wiring harness in the engine compartment? I checked as much of it as I could see and it looked okay. Where does this harness enter into the passenger compartment at? Down by the fuse box?

 

That's unusual.... those are virtually ALWAYS smoked. But, whatever.

The ENTIRE harness for the HVAC system, including the vacuum line(s), goes through the firewall on the pass side between the trans tunnel and the evaporator housing, below the heater hose nipples.

 

Okay, so I traced the harness and everything looks okay there too. I'm really running out of ideas here. Any more ideas? Could it be the blower resistors?

Thanks.

 

Hey I can see the connector now!!! The pic didn't used to be there, but it is now.

The connector looks to me like the whole side of it is burnt off, all around the little blade. All that gray and white stuff there, used to be plastic; but now it's ashes.

The reason it's stupid, is that the plastic actually holds the metal pieces together; so when they melt and burn up like yours has done, the metal parts don't actually touch any more. The electrons then get real ornery, and won't respond to their owner's will, and they'll refuse to jump across the gap for you.

Plug it back together, turn the car on and the system on and the fan to the 3rd speed, and see how much voltage there is on the side going to the control head. Or, just replace it with a better designed connector, such as the BIG FAT yellow insulated slide terminals; and see what you get then. Because as surely as the sun will rise tomorrow, if you don't change it now, you'll be right back again to where you are now, sooner or later. If there's no 12V on the control head side, see how much voltage there is on the side coming from the car. If there's 12V on one side but not the other, then that isn't a connector any more, it's just dead weight. If there's no 12V on either side, start looking back toward the fuse. If there's 12V on both sides, then see what other wires have 12V on them; the green one (compressor wire) should if you have it in an A/C position, and the wire from the "mode" switch to the fan switch should, and one of the 4 wires going toward the blower should. Instinct tells me you won't have to go through all that though, replacing the connector will take care of it.

Incidentally, add yet another car to my list.... one of my little brothers has a 87 Monte Carlo SS, called me yesterday and told me his entire HVAC system didn't work; he did EXACTLY what you're doing, except he replaced the connector; and guess what!! he has A/C now. I think your situation there is contagious.

 

Sounds good, sofakingdom. I'll go ahead and switch that connector out and replace it with a slide terminal.....*hopefully* that will solve this problem.

Thanks,
Joe

 

Well, the connector has been replaced and it still doesn't work. I don't have a voltmeter handy so I'll have to go out and grab one tomorrow. I was able to (with some minor body contortions) physically check the brown wire that runs from the fuse through the connector and to the HVAC unit...it appeared okay (I thought perhaps it came loose behind the fuse box, but it appears okay).

Thanks,
Joe

 

Okay, I got the blower motor to run! Turns out the ground from the motor was bad. However, with the car not running but the ignition switch in run, the motor does work but next to no air comes out of the vents at any speed. Does the car have to be running for air to come out? I'll try starting the car and turning the air on later, just curious.

A BIG thanks to everyone who helped me. I appreciate it!

Joe