po9rs4ch4e

i know theres been a million ac questions on here but i was wondering, in the pics below if the two wires should be plugged into the piece that attaches to the ac dryer. or what are they? also wondering if the black screw cap is the low side port for recharging the ac because the recharge can hose wouldnt fit on it.

my car is a 1985.5 with a 91 S2 engine btw.
the receipts say that a new ac compressor was installed and charged with r134 so i believe it is not still r12, but the receipt is from 2004





thanks a lot

xsboost90

someone jumped out the high pressure switch. Prob. a bad switch- which means if your fans go out and the condensor gets real hot the compressor will just keep running. The can comes w/ a new style fitting so you'll need the adapters from that fitting to the new style- and the suction is either on the ds strut tower or on the compressor- that is the high side.

pnbell

Yup someone jumped the High Pressure Switch indeed... This will also allow your compressor to run with no Oil/Refrigerant; which would burn the compressor out quickly

po9rs4ch4e

Is replacing the high pressure switch as easy as unscrewing and putting a new one on? i couldnt really find much about replacing it from the search so i imagine its pretty simple but i wanted to make sure.

pnbell

yup, easy as that. and pretty cheap.

Crimson Nape Racing

the pressures are different for R134 & R12. It is possible the old switch is fine but it won't work with the pressure of the R134 system. Also, if you have old R12/22 hoses, they will not fit on the R134 fittings (they did that on purpose so people like us could not put the wrong refrigerant in). My 89S2 has the low pressure charging port right at the compressor on the bottom of the car. The one in your pic MIGHT be the high pressure port.

DarylJ

That's entirely incorrect. The running pressures between R134 and R12 are within 20 lbs on the high side and even less on the low side. No one changes pressure switches on conversions.


That's why a proper conversion includes R134a adapters that screw on to the R-12 service ports. Having those is your big hint that the system has been converted.

It is.

Crimson Nape Racing

^^^ well at least I got 1 thing right.

po9rs4ch4e

So I got a new switch and I couldn't find any ports on the compressor to do the recharge so I guess my low side port is the one next to the ds strut tower except both the ports are the same size fittings so the recharge won't fit on either one. Does this mean my system is r12? Even though my receipts from back in the day say a new compressor charged with 134 was installed. Maybe they messed up and forgot to do the fittings? is there a way to tell if it's r12 or r134? Any help or suggestions on what to do is appreciated

DarylJ

Yes, the one near the DS strut tower is the low port.

As to what's in there.......that's a tougher question. If you have any doubt, you should pull the condenser and pump and empty them of oil, clean them out as well as the hoses and evaporator with a flush kit and replace the dryer. The basic problem is that the oil for R-12 (mineral) and R-134 (PAG) aren't compatible, and each refrigerant will only mix with the proper oil. Screwing that up by leaving some of the wrong oil in will pretty much trash the compressor.

If you're a gambling man who has a pressure gauge, you could hook it up, and hope that you have some liquid refrigerant in there still. If you do, you can tell by the pressure (if you know what temperature it is in the engine compartment.....so do this cold) by looking it up on a refrigerant chart. If you have the proper pressure for the current temp for either R-12 or R-134a, you can be reasonably sure that's what's in there, but still not 100% sure. If you have less or more, you're pretty much just guessing.