over charging

71cut442 on Tue February 09, 2016 5:18 PM

Year: 1971
Make: olds
Model: cutlass
Engine Size: 350
Refrigerant Type: 134a
Country of Origin: United States

doing my winter project on ac system. i replaced compressor (rebuilt) expansions valve, dryer ,calibrated pov 1/4 turn and flushed condenser and evaporator .old compressor front seal blew about 5 years ago due to me over charging .
I add 10 1/2 oz of Easter oil 6 oz to new compressor 2 oz to evaporator 1 oz to dryer and 1 1/2 oz to condenser as shop manual states . put everything back together ran vacuum for about 6 hr and let sit over night and ran vacuum for another 2 hr . next day i added 4 -12 oz cans of 134a (3 pounds) system take 4 pounds of r12 at 75% . should add anther 1/4 pound ? when adding 4 cans the low side got to 29 psi and high side at 205 temp at vents was 39 this was done at idle 750to 800 RPM . the next day i checked it at 1800 RMPS low side 15 and high side 150 all lines iced up vent temp 30 outside temp about 35 inside garage temp with car running 75 . Do i add the another 1/4 pound i don't want over charge and blow another compressor .

TRB on Tue February 09, 2016 5:24 PM

Check for leaks before adding more refrigerant.

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71cut442 on Tue February 09, 2016 5:33 PM

No leaks bin watching for a couple days now

71cut442 on Tue February 09, 2016 5:44 PM

What should low side and high side read for that year car?

bohica2xo on Wed February 10, 2016 1:57 AM

With 35f ambient temperatures, it is very hard to do a charge adjustment on a converted system.

The POA system has two "Low Side" readings. The evaporator pressure, which should be a steady pressure that is controlled by the POA - usually 35 psi or so. And the compressor suction pressure, which can be much lower than the evaporator pressure depending on conditions.

Your high side pressure will be relative to the ambient, the type of condensor & the airflow over the condensor. High side pressures beyond 2.7 times the ambient temperature many times indicate a condensor issue of some kind.

Stop adding refrigerant until you can get an ambient temperature that is in a range where you would actually be using the A/C for cooling.

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71cut442 on Wed February 10, 2016 6:20 AM