OK, I've been searching and just can't seem to find the answers I need.

I have a 1987 SDL Turbo Diesel. I took it in to get the AC looked at. The mechanic tested it, found that it was 2 lbs low on R134. Put it in. Said that the AC Relay was bad. Put that in.

When you start the car, the compressor kicks on right away. I let it sit there and idle for 15-20 minutes and it works great. The minute I started driving, the compressor stopped. When I was coasting down the road, about 60 seconds later it kicked back on, but then turned off right away as I started to accelerate again. When I parked the car, it took just over 60 seconds to start again.

Is this normal. I've read where the compressor shuts down to provide more power to the engine and also so it does not lock the compressor up with the high RPM's the engine is running while accellerating. But it just seems a little strange. Can anyone help me out.

David

It's quite normal for the compressor to cycle itself based upon the temperature of the evaporator.

The real question is whether the inside of the vehicle was at the desired temperature and the fan was on low speed. The compressor doesn't need to work very hard unless the blower is at one of it's higher speed positions and adding quite a bit of heat to the evaporator.

Your compressor drive belt is slipping. The compressor senses the slippage and shuts down to protect the belt drive.

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2012 E350
2006 Callaway SC560

When the compressor is shut off for this reason, you must turn the car off and back on for it to be operational again. He says his compressor comes back on later, so I think slippage can be ruled out.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Yes, I was quite surprised, having thought for years that you had to turn the engine off and back on. One day, I was not in a position to turn off the engine after a slip (I heard the belt slip and the compressor disengaged). I was pleasantly surprised when the compressor came back on line after a minute or so anyway. My belt was loose and it did this every time it slipped, until I replaced the tensioner. Then the compressor didn't disengage any more.

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2012 E350
2006 Callaway SC560