bureau13

My compressor sprang a leak at the shaft seal, so I just installed a rebuilt unit, along with a new drier. I vacuumed the system down for several hours, then added freon (134a). I used POE oil in the compressor, FWIW.

My question is about pressures. I know there is not a hard and fast rule, but I've read elsewhere on here that people found high side pressures around 250. However, my high side pressures were up to around 300 after putting in about two cans of freon, and that seems odd. The AC was working and cooling, but I did notice the aux condenser fan came on (sitting there idling, my engine temp gauge was at the top middle line, which is about when it should come on, so I don't know for sure which sensor triggered it).

StratfordShark

The pressures will depend on outside temp. What was the temp? High side 300 would correspond to outside temp of around 130F so it sounds far too high. You would only see 250 at temps around 100 so again I doubt that's a frequently seen figure, more typically high pressures a little over 200 with a full charge. How much was in the cans? I believe a 928 with R134a conversion takes 860g with no rear AC, 1050g with rear aircon.

bureau13

No rear AC, two cans would be close to 800g. So I don't think I put too much in. Outside temps were probably high 80s. Hmmm...now I'm afraid to run it....

bureau13

OK, I just checked, my gauges show static pressure of about 105 psi, and when running, it stabilized at about 200psi high side, 25-30 low side. That seems more normal. Ambient is probably mid-80s. But I don't know why it's different now. I will have to keep an eye on it and see if it stays this way over time. I suppose I could have some sort of leak still.

StratfordShark

Those pressures sound normal at that temperature. Was that at idle or around 2000rpm? Should really be reading pressure and temperature at the centre vent at the higher rpm. The pressure will be higher if fan not pulling air through condenser (not sure what arrangement is on your car or your model - mine is S4 and both fans run full blast whenever AC on).

joejoe

134 runs higher pressure than r12. For r12 those pressures sound a bit low (200/30) 134 will run higher near 300 (hence the need for new hoses, (at least 1 reason)) The low should be around 35 or so for 134.

bureau13

That makes sense. I think the first reading I took was after I had been adding for a bit, with the car idling and no condenser fan on (yet) so that would also contribute to higher pressures I think. I'll keep an eye on it, but I think I may well be in expected territory after all.