# 2000 Nissan Frontier A/C Pressure



## Norman23 (Mar 2, 2010)

What should the suction pressure run for my truck? I need to ad refrigerant to my ac. I have a 134A set of gages. I use to work on residential ac. How is the evaporator pressure controlled? By a pressure switch or by a thermostate strapped to the evaporator? What is the cut in and out pressure? Any and all information you can give me will be appreciated. Thank You Norman:waving::waving:


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## SPEEDO (Jun 9, 2003)

Not sure, but I thought the a/c label under the hood had the needed info on it...


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## Cusser (Apr 16, 2004)

Norman23 said:


> What should the suction pressure run for my truck? I need to ad refrigerant to my ac. I have a 134A set of gages. I use to work on residential ac. How is the evaporator pressure controlled? By a pressure switch or by a thermostate strapped to the evaporator? What is the cut in and out pressure? Any and all information you can give me will be appreciated. Thank You Norman:waving::waving:


I've done a fair amount of automotive AC work. However, my '98 Frontier 4-cylinder has 155K miles (I've had it almost 6 years), and its AC system has never been touched, and it's the coldest of any vehicle I've ever owned (Arizona, yet). That said, the sticker information or the Haynes manual I have don't help you much with these. I believe the AC control is from a heat senser that sits inside the evaporator and leads to a switch on the outside of the evaporator box (under dash, passenger side); usually these kick "off" at 34 degrees and "close" the circuit to turn the compressor on at about 38 degrees. Typical R134a pressures (say a 90F day) run from 25-35 psi for the low side and 240-280psi on the high side, measured after a few seconds at 2000 rpm. I believe you stated on another board that yours is a 2000; you may have lost a few ounces of refrigerantover those years, and a small loss over time is considered normal. I'd first hook up gauges, and if your high side is running low, then add one 12-ounce can of R134a. AC systems using R134a are a little more sensitive to refrigerant level than the older R-12 systems; even if there is a sight glass, that doesn't mean much with R134a systems.


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