New Sanden Compressor: High Suction/Low Discharge Pressure?

Sjohns4 said:

It’s been quite awhile since I changed the vac pump oil…I’ve probably pulled over a dozen systems down with it, both 134 and 410.

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Sjohns4 said:

Figured it out. It was the manifold gauge connector. Something was going on that it would register the vacuum and it would register the pressure the first can put in the high side port with the engine off, but it would not respond to the drop in pressure when compressor cycled.

A new set of Chinese couplers on a HF manifold set and we’re back in business.

I didn’t weigh the charge, but by the cans I should have been very close to 4#. Discovered my thermocouple was bad on my electronic t-stat, so best I could read my analog one I was between 5-10 degrees superheat at the accumulator.

Things I noticed:
The rear suction lines were cold long before the evaporator outlet/accumulator inlet was cold. Even after the air in the front was blowing cool. Didn’t matter if the rear was on or not.

I started charging with both front and rear blowing. Suction and discharge pressure was around 50/200 but I was still short a couple cans and really high superheat. Kicked the rear off and pressures dropped…suction to around 30.

After another can or two and I kicked rear back on. Didn’t notice much difference one or off after that until I was finished.

Was blowing pretty cold in the driveway but didn’t measure the temp. Give it a good test run tomorrow with the sun’s out. Has to be better than the last few weeks in the heat without. Didn’t realize how tough I used to be in the old square body…

Thanks for the advice.

Mike

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