Does anyone have a table or even any basic values of what the r12 a/c high side and low side pressures should be for given ambient temperatures? (Preferably in psi, but I can convert them if you tell me what the units are.)

(This is for a '93 SC400 with an unmodified r12 system.)

I'm very familiar with r134a and r1234yf systems on new cars (EPA 609 and ASE certified with a fair amount of experience), but this is the first time I've worked with r12. I believe the low side should be comparable to r134a, but the high side should be lower.

I know you can just charge it until the sight glass clears, but from what I've heard, that's not terribly accurate, and can often result in overcharging. Ideally I would charge by weight, but my system is just a bit low, and I don't have a way to recapture the r12 (I think it may have leaked because the seals dried out from prolonged disuse, so it may not need any repairs, once the oil is circulating again).

I looked on alldata, but it didn't provide any values (it has some pictures of what the gauges should show, but they're in units I'm not familiar with, and I cannot discern what the units are, to do a conversion).

Do the r12 sc400s use variable displacement compressors or fixed (cycling) ones?

(I am not interested in converting to r134a.)

Thanks, in advance!

 

Anyone?

With r134a, manufacturers often provide a chart detailing normal high and low side pressures (ranges) for a given ambient temperature. I cannot find that information for this vehicle (on AllData), so I assume that such a chart was not provided, but perhaps someone has a generic chart, or some idea of what a normal high side pressure would be at relatively low ambient temperatures (60-70 degrees)...?

Thanks, in advance!