AC Pressure readings are high [PICS]

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Picflight
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AC Pressure readings are high [PICS]

Post by Picflight »

1996 Grand Cherokee 5.2 with Manual climate control.

Installed new compressor, condensor, evaporator, accumulator and the high and low pressure lines which makes the the whole AC system new.
Condensor, liquid or low pressure line and accumulator are aftermarket and rest is Mopar.

Had a local shop vacuum test, evacuate and add 28oz of R134a with dye.
Temp at middle vent was 42F, not bad for 10AM and ambient temp 70F.

Next day AC was not cooling as it should considering it is a new AC.
88F ambient with 30% humidity and vent temp was 68.

Took it back to shop, no leaks found with UV and electronic detector, recover refrigerant and the machine measured it to be 1.82lbs, same as was added. So this confirmed that there is no leak.

Gauge reading are both high (60, 300 PSI) at 34% humidity and 84F ambient with vent temp 60F.
The chart says it should be 32-42 PSI, 200-260 PSI with vent 33-44F.
The compressor clutch is engaged all the time.

The pressure diagnosis chart in the service manual suggests the following for this condition:
Restricted condensor. Restricted Discharge line. Radiator overheating. Air in system. Overcharged system. Cooling fan inoperable.

Radiator was flushed and new thermostat installed, it does not overheat at all. Everything was meticulously installed and caps left on each component till the last minute for connections.

The vacuum test done by the shop was 15 mins attached to their machine which they claim is automatic and does everything.
The shop also had a very large diameter fan running close to the radiator to simulate moving car while checking, same results.
Then they filled with 1.45 lbs, less than recommended and still same results, not very cold and high pressures.

What could be wrong?

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Dougflas
Posts: 379
Joined: Mon Apr 18, 2016 6:10 pm

Re: AC Pressure readings are high [PICS]

Post by Dougflas »

Mist the condenser with a water hose. If pressures drop radically, you have an airflow across the condenser or a condenser that is not rejecting heat from the refrigerant. Engine rpm 1500, system on max, high speed blower, doors/windows open. You may also have a hose that is collapsing.
jeepsj
Posts: 77
Joined: Mon May 16, 2016 1:41 pm

Re: AC Pressure readings are high [PICS]

Post by jeepsj »

The electric cooling fans on those do go bad. Make sure the electric fan is good and that the mechanical fan clutch is in good shape.
99 Jeep XJ
87 Jeep Grand Wagoneer - 6.5 turbodiesel
87 Chevy CC Dually
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