1966 Oldsmobile A/C

[Mikel]

Hello,
I've been working to revive the A/C in my '66 Toronado. I rebuilt the A6 compressor, had the hoses remade, replaced all o-rings, dryer, flushed the system, added 10 oz of PAG oil150 and 30oz of R152a (manual called for 4 lbs of R12, so 60% of that).

I had tested the POA with compressed air and set it to 30 PSI. With the system running, it still read 30 PSI. High side was 80 PSI. The hose coming out of the evaporator was cool, but after the POA, it became very cold, to the point that frost was forming on it. Outlet air temperature was probably in the 50s (60deg day).

Any suggestions?

Thanks.

[Cusser]

I'm not familiar with that R-12 replacement, but 80 psi high side seems awfully low.

So PAG oil is used with R152A? Didn't know that either.

[Mikel]

It does seem very low to me too. But if the system called for 48oz of R12, it is already filled to 60% of that in R152A. I don't want to overcharge it.

Thanks.

[JohnHere]

Something to consider: I know you said that you rebuilt the compressor, but it sounds to me like it's not up to the task of making normally expected pressures.

I'm not an expert on R-152a conversions, either, but I happen to know that PAG and ester oils are compatible with it.

[Mikel]

Hello,
By rebuild, I should have said disassembly, cleaning and resealing. Nothing inside looked worn out.
Thanks.

[bohica2xo]

Ok, why are you running 152a?

And why is the POA set to 30 psi?

.

[Mikel]

Ok, why are you running 152a?

And why is the POA set to 30 psi?

.

R152A as a R12 alternative. I was under the impression that 30 PSI was the correct pressure for R12.

Thanks.

[Mikel]

What is puzzling to me is that the hose from the expansion valve going into the evaporator is just mildly cool. But from the middle of the POA downstream, it has frost forming around it, as if the POA was acting as an expansion valve.

I supposed it could be clogged internally in some way, but it seemed to be regulating low pressure quite well at 30 PSI.

Thanks.

[bohica2xo]

152a is not a replacement for R12. Either convert to 134a or keep it R12.

Since you already have PAG in the system, recover the flammable keyboard duster gas, and charge it with 134a.

The 30 psi setpoint should be ok in a mild climate with 134a

Charge by weight. Use 90% of the R12 charge weight as a starting point.