Author Topic: Burning Climate Control Wires  (Read 140 times)

sethkestenbaum

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Burning Climate Control Wires
« on: 09 September 2020, 10:46 AM »
I've been working on my car's climate control systems and got everything working. Everything was fine for two weeks. In the first week of it working I swapped out my climate control panel with one from my parts car which was cleaner.  At the time I noted the melted wires on the original part (from the photo) and assumed it was just old melted wires and nothing to worry about.  The replacement from the parts car (or at least as I remember it) didn't have this.  All was good for a week and then BLAMMO -- the new AC Compressor seized and melted its connection wires, the blower stopped working and i smelt smoke from my dash. The compressor has since been replaced and seems to be working.  The blower motor still doesn't work.  I decided to take out the control panel to see what was happening.  It now shows the same melted wires as the one I took out.

What would cause this problem?  Thoughts/Suggestions on how to troubleshoot this? 

Thanks -- Seth
« Last Edit: 09 September 2020, 11:54 AM by sethkestenbaum »
Seth Kestenbaum
oldcarroadtrip.com
1929 Model A Ford Phaeton
1969 VW Bug Convertible
1980 300 SD Turbo Diesel getting fixed up
1980 300 SD Turbo Diesel rusty parts donor car

sethkestenbaum

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Re: Burning Climate Control Wires
« Reply #1 on: 10 September 2020, 02:34 PM »
Today I went to move the car and to add to the mystery of my climate control system, the blower was working.  This stated, the wires behind the switch heated up quickly so I shut everything off.  I am still trying to determine the "why" and am open to troubleshooting suggestions. What are the typical causes of this wire overheating which I am told is common to the system?  Could this be an issue with the climate control amplifier?  I think I remember a post talking about a fire behind the control panel due to a bad amplifier.
« Last Edit: 10 September 2020, 02:43 PM by sethkestenbaum »
Seth Kestenbaum
oldcarroadtrip.com
1929 Model A Ford Phaeton
1969 VW Bug Convertible
1980 300 SD Turbo Diesel getting fixed up
1980 300 SD Turbo Diesel rusty parts donor car

daantjie

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Re: Burning Climate Control Wires
« Reply #2 on: 10 September 2020, 03:20 PM »
Not sure if this will help, but check if your servo unit is "parking".  When you turn the ignition off, you should hear a whirring sound, which is the servo moving into the parked position.  Also one would think that a fuse in the system will blow before frying anything, so that is a bit odd.
Daniel
1977 450 SEL 6.9 - Astralsilber

sethkestenbaum

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Re: Burning Climate Control Wires
« Reply #3 on: 10 September 2020, 06:07 PM »
It was intermittently parking in the past.  The fuse seems fine.
Seth Kestenbaum
oldcarroadtrip.com
1929 Model A Ford Phaeton
1969 VW Bug Convertible
1980 300 SD Turbo Diesel getting fixed up
1980 300 SD Turbo Diesel rusty parts donor car

sethkestenbaum

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Re: Burning Climate Control Wires
« Reply #4 on: 14 September 2020, 07:30 AM »
My efforts to address the smoking wires this weekend resolved nothing so I am hopeful some electrical detective from the forum can help.
What did I do? I swapped out the climate control panel …. The blower motor still didn’t work.  There was power getting to the connection to the motor but the motor didn’t seem to run. I removed the blower motor to bench test it. It worked fine once out of the car and then worked fine when I plugged it back into the car and after I snugged in the climate control vacuum connections (some were loose).  I then decided to see if I could recreate the wires heating up and try to narrow down my search.

What did I find?

If I have the AC compressor “on” and the blower motor “on”, then the gray wire that goes into the back of the pushbuttons in the climate control system heats to the point where it smokes the plastic around it – this is "start a fire hot" and not just “warm”.  This is happening with both the original and replacement climate control system – so I don’t think the problem is with the the climate control push button panels.  I suspect some type of short or something is over drawing current and this is where the circuit is showing the symptom of the problem.  Any insight from the w116  electrical detectives?  Suggestions?  I have a wiring diagram but haven't been able to diagnose the source of the problem.

« Last Edit: 14 September 2020, 07:58 AM by sethkestenbaum »
Seth Kestenbaum
oldcarroadtrip.com
1929 Model A Ford Phaeton
1969 VW Bug Convertible
1980 300 SD Turbo Diesel getting fixed up
1980 300 SD Turbo Diesel rusty parts donor car