heater/ac motor
Thread Starter
Racer
Joined: Jul 2012
Posts: 420
Likes: 3
From: deposit new york
heater/ac motor
hi everyone, i am having another issue on my 81 c3, i cant get the heater/ac blower to engage at all, i replaced all the fuses, removed consel and made sure the connections were good, when i move the vent selector and hot to cold i can here it move and i can here the heater make some sort of noise when i move it to the heater side, but not blower motor at all, any thoughts?
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
You need a test light or a voltmeter. Here is the circuit I give out to help troubleshoot the AC/Heat blower. There is a resistor pack on the firewall next to the high speed blower relay, passenger side by the AC box.
Thread Starter
Racer
Joined: Jul 2012
Posts: 420
Likes: 3
From: deposit new york
thanks, where is the fan relay and heat resistors, under the consel i see there is a pretty big plug connection that has nothing to it, just behind the heater controls close to the shifter. i am thinking the relay is on the firewall next to the alarm swith but not sure?
Thread Starter
Racer
Joined: Jul 2012
Posts: 420
Likes: 3
From: deposit new york
also since i removed the center consel previously (it was never put on right) i got it to fit back together and bolted in (for the first time in many years i am assuming, lol) now the heater controls seem to catch on the ashtray door, is there a trick i am missing to getting it back in position so it all fits right and doesnt catch on the ashtray, but still sit right?
Instructor
Joined: Apr 2011
Posts: 167
Likes: 0
From: Jacksonville Florida
Fan relay and heat resistors are in the engine compartment passenger side near/at firewall. The heat resistors are fastened to the top of the evaporator box. Only the connector is out of the box. You should be able to identify most of this with wire colors from the schematics.
The high speed is fused separately from the other speeds( fuseable link to starter). The fan relay is normally closed for speeds 1-3 and normally open for high speed circuit. When a/c controls select high speed the relay is energized and closes high speed and opens speeds 1-3. Speeds 2 & 3 are selected from the a/c controls and energized their respective terminal on the heat resister. The speed 1 terminal is always hot when the ignition is on. I think the 81 stays on low speed full time.
The high speed is fused separately from the other speeds( fuseable link to starter). The fan relay is normally closed for speeds 1-3 and normally open for high speed circuit. When a/c controls select high speed the relay is energized and closes high speed and opens speeds 1-3. Speeds 2 & 3 are selected from the a/c controls and energized their respective terminal on the heat resister. The speed 1 terminal is always hot when the ignition is on. I think the 81 stays on low speed full time.
Last edited by 77vetteluva; Aug 5, 2012 at 11:23 PM. Reason: poor explanation
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Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Maybe. Jumping the red and ppl made the motor run on the high speed wireing, motor and ground are good. Now you need to know if the other speed electrics work. If you don't have a voltmeter you can make a test light with a 12v light bulb, brake or turn signal lamps work good for this. Check the Brown wire at the resister block, if you have power there the fuse (25 amp AC fuse) is good. Next put the test light on the Yellow, then Lt Blue and then orange wires and move the fan speed selector from low, to med, then high. If you have power at those wires, pull the resistor block out, see if its burned. Last item is the relay. You can use jumpers to connect power to the coil side, it should click.
Thread Starter
Racer
Joined: Jul 2012
Posts: 420
Likes: 3
From: deposit new york
with the key on i cant get any power at the brown wire at the resistor block or any other connection at the resistor block, but if the relay was bad would i be able to get power at the block?? i took out the resistor block and checked it, it seems ok, a few rust spots, but all the springs are connected and look good.i replaced every fuse in the fuse panel (just to be sure). i am not sure which terminal at the relay to check with 12v to test it, i couldn't make it "click". any help is greatly appreciated, thanks
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
No power at the brown wire sends you back to the fuse or the fuse block or the firewall connector. With the key on, check for power on both ends of the AC fuse. 2nd from the top, second from the right, 25 amp. You may need to follow the brown wire back from the resister block to the firewall connector, who knows? Bubba may have cut it.
Thread Starter
Racer
Joined: Jul 2012
Posts: 420
Likes: 3
From: deposit new york
the actual wire harness after the firewall in the engine bay looks original and i cant follow it back much past the relay, its in a sealed wire loom, i dont see a connection just the brown wire entering it. do you have a diagram of the fuse block, if my memory is right i have a red 10A fuse first on left, then a 20A. i found 1 diagram but it does not match what i have, i have a flasher (ithink on the top left) and then another flasher (bottem right) this one has some sort of resistor or something wired into it (looks very corroded, but i dont know what it is so i can replace it)
Thread Starter
Racer
Joined: Jul 2012
Posts: 420
Likes: 3
From: deposit new york
well i found the problem you were absolutly right, the problem was at the fuse block, the old fuses that i replaced was blown, but had been in there forever and was corrodided, i replaced the fuse but did not clean the contact on the other side, cleaned it and boom, the heater fired back up, of course i have leaks somewhere, the defrost is very weak, but the floor and vents seem to have good power, so i think the vent going up to the defrost is off a little. the AC is not cold, but i am sure it just needs to be recharged. thanks soooooooo much, 1 more little issue fixed 