A/C compressor not working

TOMMYOGG

MEMBER
2002 NISSAN XTERRA
6 CYL
2WD
AUTOMATIC
88,000 MILES

This year my a/c did not seem to be cooling very well. It would cycle on and off too frequently. I figured it was low of freon so I purchased a gauge and can of R134. When I installed the freon the gauge was reading 0 when the clutch was not engaged. When the clutch engaged it jumped to 20. The instructions told me to charge it to 45-65. The whole can was installed and the pressure read was 45. The air was cold and the compressor did not seem to cycle much. This last for about 2 days. It then began to blow warm air again and started to cycle too often again. I thought maybe it was a leak so I bought a can of dye and hooked up the gauges. This time, with the gauges hooked up and the clutch engaged the pressure shot up to about 100 and then about 75 when the clutch was not engaged. I began to think I overcharged it so I let some freon out and then the air began to blow cold again. This lasted about a day and now the air is hot again. Is this typical of a malfunctioning a/c compressor? Thanks, Tommy

Tuesday, April 29th, 2008 AT 7:20 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

The pressures you mentioned that "shot up" to 75 and then 100psi is a concern. I really need to know if that was the high or low side pressures. If it was the low side, something must be plugged for it to climb that high or the compressor is going bad.

As far as the 75 with the compressor not engaged, that is considered static pressure. However, usually you need to wait a bit for it to equalize. If the static pressure is 75 PSI and the ambient temperature is around 75 degrees F, that is normal.

What I would really need from you is what the high pressure and low-pressure readings were then the system is operational. In addition, the ambient temperature makes a difference, so that is needed as well.

As far as the compressor being bad, it is very possible. The idea that when it was running it showed 100 PSI, which is extremely high for the low pressure. Here is what to keep in mind. If the low-pressure side is high and the high-pressure side is low, suspect the compressor is failing. If both sides are high, it's likely overcharged.

What I suggest is to start from the beginning. Evacuate (vacuum) and recharge the system using A/C manifold gauges. Here is a link you may find helpful. It explains the procedure. Note, make sure not to add too much oil.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

If you determine the compressor is bad, here is a link that shows in general how one is replaced:

https://www.2carpros.com/articles/replace-air-conditioner-compressor

If you look at the attachments below, they provide the directions specific to your vehicle for compressor replacement and adjusting lubricant for compressor replacement.

I hope this helps. Let me know if you have other questions.

Take care,

Joe

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