Geday from Australia!
my darling 1987 300D has had a conversion to the new aircond gas (is it R134?), and on her history a few years ago a mechanic said there was a "slight leak at compressor"

Now the cool air is temperamental... often works straight up, then after , maybe 10 mins, maybe an hour, dies away to nothing, but I can tell by the lack of power the compressor is still running. If I turn it off for 30 mins, then back on,sometimes it works again. It's never super cold.

What do youse reckon? I am dreading the big $2000 repair!

If it's been a few years since you've had a set of gauges on the system it's time to see what the high and low side are up to. Take the car to a shop and have them put the gauges on the car. It could be that the charge is simply low of gas or, you may have a failing component.

- edit -

In any case, if a leak exists, it should really be taken care of. A leak can be found with a halogen leak detector or other similar sniffer. Any a/c shop will (should) have a detector.

You also need to check the evaporator temperature sensor. If it has failed, it may allow the evaporator to freeze up.

Most likely you have a combination of low freon and a bad temp sensor, so you never get good cooling, but the evaporator freezes over, at which point you have none.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks guys for excellent responses. I can walk in to the shop sounding intelligent now.
I should add that it seems to work better in hot weather than medium weather- when it sometimes hardly works at all.

That probably rules out the low charge then...usually when the systems are low they peter out as the ambient temperature rises. Yours does the opposite, so that leaves us with the evaporator sensor, which would make sense. The higher air temps at the input to the evaporator would prevent it from freezing up as quickly.

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Dale

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1990 300D 2.5 Turbo -155k
2000 E430 - 103k
2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k
2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz

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It could be a restriction at the receiver or expansion valve.