140 Climate Control Wiring Harness???

[wbrian63]

Thanks to MB Doc for replying to the previous question about a "reluctant" A/C system. Now if I can get it to misbehave long enough to pull the cover off the blower and check the signal voltage...

I indicated in the previous post that I didn't think I had any DTC's stored - I was wrong.

I checked this AM and found these codes:
43 - ECT Sensor / open short
75 - Coolant circulation pump - open / short circuit
91 - A/C compressor ground activation - open / short circuit.

All 3 of these errors are classified with a footnote #3, which indicates intermittent faults.

Other issues noted - with the temp dials set at the same position on the climate control, the temp of the driver's heater core is always 5-6 degrees higher than the passenger (and you can tell it in the temp of the air from the left center vent vs the right center vent).

Several times over the past week or so, the fan, while blowing at an accelerated level, has abruptly turned off, then back on again.

Yesterday, while trying to get comfortable (I was hot but the inside/outside temps were in the high 60's with 100% humidity) - I set the temp dials to LO. After about 5 minutes at this position, I began to smell the unmistakeable odor of cooking resin. (Worked for years at a company that manufactured a variety of high-temp fiberglass products - know the smell well). I think I was cooking my brand new Unwired Products fan speed regulator. I'll have to pull the cover off to check my suspicions. The fan speed was set to AUTO, but when I backed the temp dials down to 68, the smell went away.

The main engine harness on this car has been replaced, along with the charging/starting system sub-harness. However, the wires that go to the A/C compressor are showing the dreaded signs of insulation degredation.

The coolant circulation pump has been replaced - probably needlessly, when the climate control (before I had it rebuilt) indicated the same error. The original pump would run, but it was a bit noisy, so it would have probably failed eventually.

I'm thinking these intermittent problems are symptomatic of a A/C harness that is packing it in.

I need to do some more sleuthing under the hood on the wires that go to the ECT sensor, the coolant pump, etc. to see if I can detect more insulation degradation.

Can others shed light on my suspicions and help me drive the last nail in this coffin? The car is dark blue with a dark blue interior, I live in Houston and I am hot-natured. I'm GOING to need a good A/C when the hot weather arrives all too soon.