Now Nothing from Heat or AC
June 16th, 2011, 11:19 AM
#1
Registered User
Thread Starter
Join Date: Dec 2006
Posts: 25
Now Nothing from Heat or AC
It was such a simple plan ... how could it have gone so horribly wrong?!?
The AC on my '71 Cutlass Convt was not blowing on the high speed (but all others worked) so I checked all fuses and replaced the high speed fan relay in the engine bay (behind the brake booster). That didn't help so I replaced the horn relay, too (because it was only $30 and easy).
BIG MISTAKE!!!
The new relay immediately popped and smoked like a firecracker, the red (hot) lines from the battery - to the relay - to the starter all started smoking and then the insulation around the console shift linkage caught on fire.
I replaced (a) the shift linkage, (b) the horn relay (back to the original one) and (c) the cooked wires from the battery to the horn relay. Everything is all buttoned up and now I get nothing from the heater/AC controls.
WTH have I done?!?
The AC on my '71 Cutlass Convt was not blowing on the high speed (but all others worked) so I checked all fuses and replaced the high speed fan relay in the engine bay (behind the brake booster). That didn't help so I replaced the horn relay, too (because it was only $30 and easy).
BIG MISTAKE!!!
The new relay immediately popped and smoked like a firecracker, the red (hot) lines from the battery - to the relay - to the starter all started smoking and then the insulation around the console shift linkage caught on fire.
I replaced (a) the shift linkage, (b) the horn relay (back to the original one) and (c) the cooked wires from the battery to the horn relay. Everything is all buttoned up and now I get nothing from the heater/AC controls.
WTH have I done?!?
June 16th, 2011, 11:24 AM
#2
Registered User
Thread Starter
Join Date: Dec 2006
Posts: 25
Here's a little more info.
Since I had my console out to replace the linkage, I went ahead and pulled the seats to replace the carpet.
... while the carpet was out, I cleaned the floor pans and painted with POR 15.
... while I was cleaning the floorpans, I noticed a big leak from the driver-side convt piston.
... while refilling the convt top reservoir, I burned out the convt top switch.
... while pulling the convt top switch, I noticed the after-market radio wasn't grounded so I grounded it to the underside of the dash.
The heater/AC worked with the new high speed relay so something has happened since the fire. Where should I look now?
Since I had my console out to replace the linkage, I went ahead and pulled the seats to replace the carpet.
... while the carpet was out, I cleaned the floor pans and painted with POR 15.
... while I was cleaning the floorpans, I noticed a big leak from the driver-side convt piston.
... while refilling the convt top reservoir, I burned out the convt top switch.
... while pulling the convt top switch, I noticed the after-market radio wasn't grounded so I grounded it to the underside of the dash.
The heater/AC worked with the new high speed relay so something has happened since the fire. Where should I look now?
June 16th, 2011, 12:11 PM
#3
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
Start from scratch and check power at every step from the battery through the fuse box through the switch, to the motor. It sounds like you've touched darn near every part of it during this process, so the problem could be anywhere.
- Eric
- Eric
June 16th, 2011, 01:10 PM
#5
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
Just make a test light by soldering wires to the contacts of an 1156 bulb and taping it up.
Put alligator clips on the other ends of the wires, and make 'em about 6 feet long each, so you can see the bulb when you're away from the problem.
Start at the battery - one clip to ground the other to the Pos terminal, then to the big horn relay terminal, then to each terminal of the fuse in the fuse box, then to the hot of the blower switch - you get the idea. Sooner or later you'll find something that should be hot but isn't.
Also, the heater motor has a separate ground wire - make sure that it's grounded.
- Eric
Put alligator clips on the other ends of the wires, and make 'em about 6 feet long each, so you can see the bulb when you're away from the problem.
Start at the battery - one clip to ground the other to the Pos terminal, then to the big horn relay terminal, then to each terminal of the fuse in the fuse box, then to the hot of the blower switch - you get the idea. Sooner or later you'll find something that should be hot but isn't.
Also, the heater motor has a separate ground wire - make sure that it's grounded.
- Eric
June 16th, 2011, 07:05 PM
#6
Registered User
Join Date: Feb 2008
Location: Plano, TX
Posts: 11,798
My guess is you knocked a connector off the AC control panel when working on your radio. Take a look up there.
This is assuming the heater/AC fuse on the fuse box has been replaced with a known good.
This is assuming the heater/AC fuse on the fuse box has been replaced with a known good.
June 22nd, 2011, 11:12 AM
#7
Registered User
Thread Starter
Join Date: Dec 2006
Posts: 25
Spent some time under the dash last night but could not find anything (new) amiss. All wires into the heater/AC unit have juice.
I'm thinking either something s wrong with the new high speed fan relay I stalled or maybe a fuse to the blower was blown - or both.
I have found something that has puzzled me for a while. I have a loose vacuum line going from the #3 position in the following diagram (from the chassis service manual):
http://i1191.photobucket.com/albums/...s/DSC02115.jpg
The vacuum line is black with a white stripe; it's attached near where the arrow labelled "L-6 connected to solid pin" is and it goes through the firewall where it is tied in a knot and plugged with a screw.
Here's some photos from under the dash:
http://i1191.photobucket.com/albums/...s/DSC02114.jpg
http://i1191.photobucket.com/albums/...s/DSC02113.jpg
... and from the firewall in the engine bay:
http://i1191.photobucket.com/albums/...s/DSC02109.jpg
http://i1191.photobucket.com/albums/...s/DSC02110.jpg
There is an unused vacuum port on my intake manifold that is now plugged.
What is this vacuum line for? My heater and A/C seemed to work without it - except for the high speed fan.
I'm thinking either something s wrong with the new high speed fan relay I stalled or maybe a fuse to the blower was blown - or both.
I have found something that has puzzled me for a while. I have a loose vacuum line going from the #3 position in the following diagram (from the chassis service manual):
http://i1191.photobucket.com/albums/...s/DSC02115.jpg
The vacuum line is black with a white stripe; it's attached near where the arrow labelled "L-6 connected to solid pin" is and it goes through the firewall where it is tied in a knot and plugged with a screw.
Here's some photos from under the dash:
http://i1191.photobucket.com/albums/...s/DSC02114.jpg
http://i1191.photobucket.com/albums/...s/DSC02113.jpg
... and from the firewall in the engine bay:
http://i1191.photobucket.com/albums/...s/DSC02109.jpg
http://i1191.photobucket.com/albums/...s/DSC02110.jpg
There is an unused vacuum port on my intake manifold that is now plugged.
What is this vacuum line for? My heater and A/C seemed to work without it - except for the high speed fan.
June 22nd, 2011, 01:04 PM
#9
Registered User
Join Date: Feb 2008
Location: Plano, TX
Posts: 11,798
Keep in mind vacuum lines will have no affect on fan operation. That is all electrical.
From horn relay junction to ignition switch to fuse to control master switch to fan switch to resistor OR high relay to blower motor to ground.
Can you get a click on the AC compressor clutch with key on but engine off?
From horn relay junction to ignition switch to fuse to control master switch to fan switch to resistor OR high relay to blower motor to ground.
Can you get a click on the AC compressor clutch with key on but engine off?
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