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High vent temps, weird pressures

JoJo88 on Mon July 11, 2011 1:07 AM User is offline

Year: 1989
Make: Toyota
Model: Camry
Engine Size: 2.0L
Refrigerant Type: R12
Ambient Temp: 95
Pressure Low: 45
Pressure High: 210
Country of Origin: United States

I rebuilt my AC system over the past few weeks:

re-sealed the compressor (Denso 10PA) & new bearing & adjusted clutch
new receiver/dryer
new barrier hoses
new expansion valve (OE)
new o-rings
flushed lines, evaporator, condenser

This rebuild was not due to "black death" or other catastrophic event; the system was just leaky.

Vacuumed using a new Robinair vacuum pump for 2 hours. Charged with 6 oz. of mineral oil and 24 oz. of R12 and 1/4 oz. of leak dye. Had to get out of friend's garage, so I left the pressure confirmation for later.

A few days later I connected gauges and found low side ~ 45, high side ~ 210. I didn't check the inlet temp, but the vent temp was 57 F.

Today I decided to hook up the gauges and adjust the Freon charge and aim for a high side pressure to be correct for the inlet temp and let the low side fall where it may. I removed some Freon until the high side pressure came down to 108 psi at 95 F inlet temps. This resulted in low side pressure of 5 (yes, five) psi. Outlet temps were ~65 F.

I then added Freon until the vent temperatures got as low as possible (~57 F inlet temp) which gave a low side pressure of 30 psi; the high side pressure was 175 at 95 F inlet temp.

I called it day.

On the freeway on the way home I could get vent temp down to low 40's with late afternoon inlet temps of 75 F. With daytime summer temps I can't get below 55.

If anyone has an idea why my pressures won't align with the temperatures (per press & temp chart) I'd like to hear it.

Testing was done at 1500 rpm, intake source: fresh, vents closed except for center vent. I didn't put a fan in front of the condenser. Is this usual practice?

I zeroed the Robinair manifold pressure gauges using the screw on the face each gauge. The needles move freely; no binding.


bohica2xo on Mon July 11, 2011 1:27 AM User is offline

There should be a sight glass on that car. Proper charge is easy enough - doors open, cabin fan on highest speed. Engine to 2000 rpm. Charge to clear sight glass.

If you find the high side pressures to be elevated with a full charge, clean the condensor air side carefully. Since this is an electric fan vehicle, the fan motor may be well below par given it's age. Very hard to tell when those fan motors are putting out half of what they should, unless you have a brand new one to compare it to.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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