<VV> 66 A/C Update

Frank DuVal corvairduval at cox.net
Sat Aug 20 22:18:18 EDT 2016

Bubbles in the sight glass means low charge.

150 still way low for 80 degree at air inlet. Just add more R-12. I
would not be concerned until the high side goes over 225. And I still
would not be concerned if the system cooled properly.

Note, and I quote the 65 manual since that is in my computer, the low
pressure reading of 11 or  so is when the compressor cycles off, not at
steady state running. The evaporator needs to get cold in order for the
thermostat to cycle the compressor, at which point the low pressure side
will be low because the evaporator is at a low temperature. With a low
charge, the thermostat will never cycle the compressor off.

Around here I do not recall ever seeing low pressure below 20 psi on a
typical day, 30 would not be bad if the system was cooling OK. Those low
readings might be car in the shade (i.e. laboratory or shop). A non
Corvair (cycling clutch system) would ice up if the low side pressure
was only 12 psi! If you look at your gauge, or an R-12
pressure-temperature chart, you will see a low side pressure of 10 psi
is zero degrees F! That's a freezer, not an A/C.

Frank DuVal

On 8/20/2016 6:09 PM, Garry via VirtualVairs wrote:
> Hi all,
> Here's what I did and found today on the 66 Monza A/C.
> Ambient temp: 80 degrees
> Static pressure: 84 psi
> Added seals to condenser, taped up all holes (not many), and ran hoses
> thru back-up light and sealed off. Engine running approx 2000 rpm, low
> side pressure was 10 psi, high was 130 psi, output temp 80 degrees,
> with bubbles in sight glass. Added small amount of R-12, maybe 1/2-1
> pound, and readings went to 18 psi low, and 150 psi high. Output temp
> now 74 degrees and still has bubbles in sight glass. I'm not sure I
> should keep adding since I'm already above the 14 psi recommended by
> the manual for this ambient temp, but what else could be happening? In
> order for me to hit the 35 degree level on the gauge, it would need to
> have a low side reading of 30 psi, well above the manual. I'm down to
> my last bit of R-12 and could probably only do one more evac and
> recharge, so I want to be fairly accurate with whatever I do next.
> Garry Parsley

More information about the VirtualVairs mailing list