Author Topic: heater blower not working  (Read 3935 times)

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Offline chris74

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heater blower not working
« on: July 11, 2006, 03:43:39 PM »
Hey All,

Chris from Savannah, Ga. I just bought a 79 T/A special edition WS6 car.
Black w t/tops.

The car is in good condition and I decided to mount a cd player in the map pocket since the dash is uncut. Heat and AC have worked perfectly although ductwork on passenger side is cracked and leaks cold air underneath before the vents. I pulled the ductwork to check things out but now on reassembly the blower motor won't turn on.

I have power to the blower switch and power leaving the switch. the a/c compressor kicks on when a/c is turned on. all fuses look good and i don't see anything obviously disconnected as i have been rooting aroung under the dash. the unit just doesn't blow air anymore at all. any ideas?

thanks

Offline Eagle 1

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heater blower not working
« Reply #1 on: July 11, 2006, 04:05:00 PM »
Do you have power to the blower motor itself?
There is also a switch behind the ac control panel which is a part of the vacumn control switch.  You may have accidently unhooked something here.
" He done good didnt he Fred?"
"I'm in pursuit of a black Trans Am. He's all mine so stay outta the way."

Offline chris74

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heater blower not working
« Reply #2 on: July 11, 2006, 04:09:53 PM »
Thanks for your reply eagle. i have not checked the blower itself. new to trans/ams i guess i'll have to pull the inner fender to have a check at that.

all the switches seem intact. i can see the flapper open and close in the heater box as i move the the switch from a/c to vents to heat etc. also, the a/c compressor cycles on and off when you turn the switch to a/c.

only no air is moving through the heater box and i don't hear the blower, even low, with the ignition on. again, i pulled the ductwork but don't have any clue as to what has caused this problem.

Offline ta78w72

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heater blower not working
« Reply #3 on: July 11, 2006, 04:18:33 PM »
It appears that your blower motor quit.  Get the replacement from Classic because their blower wheel fits perfectly.  The one I got from the auto store had a wheel that was a tad too large and would hit the sides of the A/C suitcase.

Now for the bad news.  If your blower motor quit, and you're going to remove the fender skirt anyway, consider pulling the heater box to replace the heater core.  Cause if it hasn't been replaced yet, it's only a matter of time before it will begin to leak.  And, if your A/C ducts are broken, now would be a good time to buy replacements.  They are very cheap except for the passenger side.  That one runs around $100.

The other thing to check first is that the blower motor has a good ground.  It grounds on the A/C compressor bracket.  You'll see two black wires, one thick and one thin that both ground there.

Offline 1onehotTA

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heater blower not working
« Reply #4 on: July 11, 2006, 04:19:01 PM »
I had serious blower probs.  my climate controls were butchered, so I really really dug into that whole system from under the hood.  It sounds like you have a ground problem.  When I got mine, someone ran a ground to the motor itself and to the body, other than the original ground thru the dash wiring.  I had to tear all the controls and quarter panel out to fix it.  Just some pointers, the fan runs all the time, it was a health thing back then, it runs on low due to the potential of carbon monoxide from our gas guzzlers, then the fan switch works thru a series of resistors that increase the current flow to the fan motor, then HIGH clicks a relay under the hood, and it connects the fan right to a wire coming from the alternator for HIGH speed.  The ground though comes from thru the dash wiring.  It took me many nights to figure this out, mine is a 78 by the way, not certain if yours is or not, but it may be different.  Also the HIGH speed uses larger gauge wire, I think it may be 10G going to my alternator.  I hope this helps some, this can be a nightmare, but once it works it is really cool to have an old ride with stuff that works properly believe me.
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Offline ta78w72

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heater blower not working
« Reply #5 on: July 11, 2006, 04:32:46 PM »
To overcome the ground issue, I used the original ground at the A/C bracket and I ran a redundant ground from one of the motor fasteners to the firewall.  

You can make sure you've got voltage to the motor by measuring the voltage at the orange wire coming out of the relay.  That orange wire goes directly to the motor.

If you've got 12 volt at the orange wire, and if you can see the black ground wire at the A/C bracket, it's time for a new blower motor.

It's all fairly easy if your wires haven't been cut up.  If they are, those  uncut harnesses run around $100 if you can find one on E-Bay.  I got lucky and stole one for $9.99 plus shipping....that was after bidding $100 for one and losing out to someone else.

Offline chris74

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heater blower not working
« Reply #6 on: July 11, 2006, 08:53:31 PM »
Thanks for the response guys.

I was idling in the drive waiting for my wife and all of a sudden the air starts cranking. I checked for loose wires at the switch earlier so I must have something with the connection at the blower or the blower itself. I do have both grounds at the bracket and obviously hasve power at the blower now so I'm guessing connections or old blower.

BTW, I took off all the underdash venting for the a/c because of the cracks in the passenger side ducts (gonna keep my eyes open for one on ebay). Man, that is some serious air blowing out now. I must have been cooling the underside of my dash and getting nothing for myself before.

Offline ta78w72

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heater blower not working
« Reply #7 on: July 11, 2006, 09:24:36 PM »
The motors will work then stop before they die altogether.  So don't declare victory yet.  That passenger side duct is the worst one to break.  I sold one on ebay for something like $70.  It was perfect though.  Sometimes you find good stuff at the old salvage yard! :D

Offline whwright

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heater blower not working
« Reply #8 on: July 12, 2006, 11:15:44 AM »
My passenger side duct was cracked, and I repaired it using fiberglass.  It worked perfectly, and you can't tell after it is installed.  I used "worked" -- past tense -- because later my big-footed son kicked it and now it has duct tape on it too.

If you have all the pieces, fiberglass might be an option for you.

Wayne.
1978 Trans Am
1975 Grand Prix
1971 Chevy C20
1972 ...uhem... mustang