Background- Every year I have the Freon topped off by the mechanic. He tells me the amount he puts in and it seems there's a leak. Last year he put in 1.49lbs, which he says is 75% of the 2.07lbs capacity. The leak seems to have gotten worse year to year. Also, I have been struggling over the last three years to do the resoldering in both 940s but seem to be able to adequately fix the joints to make things work for the season.

I've been in the controller unit many times and have learned that the #7 terminal is hot with fan on and the #10 terminal outbound GRN/RED wire goes to the switches and from there to the compressor. Jumpering at the low pressure terminal fires the compressor, but no cold air. I suspect low Freon.

Every year I spend $150 or so to have the pro do the AC service. How easy would it be to top off the system myself. I've been afraid to mess with the Freon but open to learning.

Any advice would be appreciated



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89 240 wagon, 94 940, 300K, 94 940, 141K

Dear Mr Pelchat,

I hope your mechanic (he knew your system was leaking) added some UV tracing dye and some refrigerant oil while doing the topping. Now is to trace any oily part of the system and attempt repair.

Which part of the system need some re-soldering? Aluminium pipe soldering is possible but need to find the expert shop to do it. Better to replace it than to solder it unless its a pinpoint leak (considering the high working pressure in the system).

Topping up using the quick recharge container sold at convenient store is easy but I would repair the leak first.

Yes, no cold air (compressor IS running) even after jumping the low pressure switch could mean low freon. Could mean other things too i.e blocked orifice tube, extremely worn compressor, blocked condenser (with compressor debris) but lets get to that later.

For environmental reason I'd prefer to repair the leak as letting the freon escape would affect the environment. The R134a refrigerant took some 10 years to degrade itself in atmosphere. While it doesn't cause any ozone depletion, it causes global warming.

Regards,
Amarin.

Amarin

Thanks for the thoughtful reply. Any soldering was done to the aging AC controller soldering connections; moderately successful on that.

He did put dye in there 6 years ago but never found anything. Perhaps that means the evaporator is leaking. Don't know if he used refrigerant oil.

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89 240 wagon, 94 940, 300K, 94 940, 141K

Well I guess, if there's no external oily area to look at then take the plunge to dismantle the evaporator from inside. On early 940s (prior to 1994) the evaporator is much easier to dismantle. This because the coolant pipes goes sideways out to the firewall. Latter 940s have coolant pipes that goes upwards thru the firewall. Anyway this might be a long repair i.e. testing the evaporator, confirming its leaking then ordering a new one and installing it back (but should be worth it i.e. could last you another 10-15 years).

Otherwise don't overlook another area of possible leak - thats the shaft seal at compressor. It would look oily too but the whole thing is hidden behind the compressor's clutch plate. You'd have to take out the clutch plate to inspect for any leak. This is still manageable without any special tool i.e. using various sizes of screwdrivers along the way from small to big, slowly prying the plate out (I did that once).

If you don't have any tool to replace the seal then getting a new compressor might be the only way.

Regards,
Amarin.

Went ahead and had the pro do the Freon refill. He said it was completely empty; it took 2.07 lbs of Freon. He also said it would hold a vacuum so the leak is not significant. Everything works well for now.
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89 240 wagon, 94 940, 300K, 94 940, 141K