My apologies for the post, MBDOC provided me the procedure a few years ago, but I cannot find it.

At this point I suspect the speed sensor on the A/C compressor acting erratically and want to disable it.

This car DOES NOT have a Klima relay. And the A/C is controlled via the ECU.

Pressures are OK, if there was an issue with the pressures then the AC would not work fine for days at a time.

I also took out the CCU and resoldered most of the solder points.

Issue persists.

Car: 1994 E420

Symptoms: Nice cold A/C, then compressor disengages. Ambient air (HOT). This happens completely at Random, no restart necessary sometimes. I could be driving with cold AC (40F off the vents on a 95F day). It goes out, ambient hot air, keep driving normally, suddenly the AC starts working again. And no, it is not the temperature control valve allowing hot coolant, I checked for that too.

Pin 8 of DM:

Code 6: A/C electromagnetic clutch jammed or belt broken (I know this is not true)

Code 7: Belt Slips (no way, new belt and tensioner)

Conclusion: This freaking speed sensor must be acting up.

Potential Solution: Disable the sensor, and keep the AC running without it

I solved the ASR issues, and now this crap (random A/C)

__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

1st step, check wiring at compressor electrial plug, broken or poorly soldered wires.

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mbdoc, thanks for the feedback. Will check this weekend.
IF wiring at compressor electrial plug, broken or poorly soldered wires checks OK
I will move to the other end - check at ECU (although I doubt this end has problems)
Then I will move back to CCU and check my soldered points.

The fact that no Klima relay exists on this car shortens my options.

What would be the next step?

__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

What does "poorly soldered wires" mean?

Someone did a bad repair with a soldering iron? The factory solder joint has corroded over time? Something else?

Thanks.

I had an engine swap from the om603 to the om606 for my w124. The 606 came with a compressor with no speed sensor. (like the SD5H14 sanden compressor). The ac compressor is not engaging. My mechanic tells me it is because of the absence of the speed sensor.

How can I disable the speed sensor? Or is there any klima relay for that compressor.

Have you tried to use the Kilma from the OM606 car? It should work if the compressor in the donor car does not support the speed sensor. The rest of the Kilma functions I would think is compatible.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.