Greetings All

1988 245, DK compressor I have topped it off w/ Freeze 12 and the system cools well at idle and low road speeds. At highway speed cooling goes away. I have checked the heater valve and it "appears" to be closing. My suspicion is a slipping compressor clutch. No slip as long as engine speed is slow. Any suggestions?

I have a new TAMA compressor but since the current comp.cools well at idle would rather trouble shoot than break open the system.
Any tips are appreciated.

thanks
danny hall

My guess would be either a slipping compressor clutch, belt, or a freezing evaporator due to charge level.
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Chris Herbst, near Chicago.

I wasn't aware that the older 200s had an overpressure shutdown switch, but anything could have been installed during the conversion. If there was such a switch installed, it could be the cause, especially with a higher pressure refrigerant like Freeze 12.
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Chris Herbst, near Chicago.

Are you getting bubbles in the sight glass. If you are then you are low. Did you evacuate the system to 29 inches of mercury? If not then the expansion valve could be freezing up.. Have you put a thermometer in the center outlet? You need to hook up a set of gauges and check and see if the low side is drawing a vacuum. If would mean a blockage possible moisture freezing up the expansion valve. good luck Dave.

With a converted refrigerant, the sight glass is useless. It is meant only for use with R12, the original refrigerant. Since Freeze 12 is little more than R134a in the first place, it renders the R12 sight glass unuseable.
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Chris Herbst, near Chicago.

Thanks for the info. Gave up being a
Volvo Dealer mechanic in 1983 used R12 back then.

Yeah, not picking at your post or anything. Just a side note because a lot of conversions are being done based on sight glass readings, and they don't work too well.
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Chris Herbst, near Chicago.