Electrical Oddity
Thread Starter
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
Electrical Oddity
'79 L82
Have the A/C working now and have noticed something strange. If I shut off the engine with the A/C system left on and blower at hi, the blower continues to run until I turn the system itself to "off" after which I can move the system switch to anything and the fan will not run. The fan will work at any speed but has to be at "hi" for the problem to first occur.
I'm clueless as the power for the hi fan relay coil comes from ignition power as does power for the other three speeds.
Have the A/C working now and have noticed something strange. If I shut off the engine with the A/C system left on and blower at hi, the blower continues to run until I turn the system itself to "off" after which I can move the system switch to anything and the fan will not run. The fan will work at any speed but has to be at "hi" for the problem to first occur.
I'm clueless as the power for the hi fan relay coil comes from ignition power as does power for the other three speeds.
Race Director
Joined: May 2006
Posts: 18,735
Likes: 2,582
did you test with a light or voltmeter that your statement about hi fan relay coil power comes from ignition is correct? It sounds like the relay is sticking in the closed position and is still getting power.
Thread Starter
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
I can understand a relay mechanically sticking but can't understand why turning off the system would un-stick it.
Thread Starter
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
It gets stranger...
The problem appeared after a 40-mile shakedown highway cruise and some shakedown errand running the next day. Both very hot/humid days with the A/C cranked. High speeds on the first; lots of idling at stop lights on the second. Both times the temp gauge went to a bit over 220F.
Couldn't get the problem to reappear with simple testing with a cold or normally hot engine.
Am now wondering if it is somehow associated with the auxiliary electric cooling fan. I know for a fact that the cabin wiring harness is exactly as shown in the schematics but am unsure of the engine harness and the oddly run pink wire that feeds the (original) aux cooling fan.
The problem appeared after a 40-mile shakedown highway cruise and some shakedown errand running the next day. Both very hot/humid days with the A/C cranked. High speeds on the first; lots of idling at stop lights on the second. Both times the temp gauge went to a bit over 220F.
Couldn't get the problem to reappear with simple testing with a cold or normally hot engine.
Am now wondering if it is somehow associated with the auxiliary electric cooling fan. I know for a fact that the cabin wiring harness is exactly as shown in the schematics but am unsure of the engine harness and the oddly run pink wire that feeds the (original) aux cooling fan.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Just waiting to see how this 'plays' out .
AS I have found there are certain members who may post a problem but in actuality...have all the ability to find it and repair it themselves.
You have my attention..but I also know you more than likely will find it and fix it yourself...especially when you found 'new' wiring and the problem is as I took it....intermittent now.
Times like THESE is when a person who keeps at it...will gain new found knowledge and thus....further increase their ability.
Not that it matters...but if you do get to a point where your head is spinning and things do not make sense....I will join in...along with others I am sure.
DUB
Thread Starter
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
Just waiting to see how this 'plays' out .
AS I have found there are certain members who may post a problem but in actuality...have all the ability to find it and repair it themselves.
You have my attention..but I also know you more than likely will find it and fix it yourself...especially when you found 'new' wiring and the problem is as I took it....intermittent now.
Times like THESE is when a person who keeps at it...will gain new found knowledge and thus....further increase their ability.
Not that it matters...but if you do get to a point where your head is spinning and things do not make sense....I will join in...along with others I am sure.
DUB
The "oddly run" pink wire for the cooling fan is, I believe, original as the electric fan was new in '79 and wasn't integrated into any harness.
Intermittent electrical problems are always the worst to diagnose and this one is particularly so; the problem has only recurred once since I first posted yet I've used the car fairly frequently.
It will have to wait until fall or winter when I make some electrical upgrades removing every main wiring harness (engine, cabin, rear) in the process. While at it I will make certain that everything tests exactly as shown in the service manual and put schematics of my changes in a clearly labeled envelope affixed to the underside of the battery compartment door.
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