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A/C Compressor

Why would my AC come on sometimes and then other times will not come on? Sometimes it blows cool and then the next time I get in the car it will not. I don’t know if the compressor isn’t coming on or if it is something else. I make sure that the AC light is on so I know it isn’t that. The original compressor in my 2007 Infinity G35 went out and I ordered a new one online that specifically fits this model and had it installed. I don’t know if it is the compressor or the person who installed it.

stick head by compressor. Have friend push ac button on/off. Is clutch engaging?


If your original ac compressor catastrophically let go, shooting metal debris into the entire system . . . and you ONLY replaced the compressor, then your replacement compressor never had a chance

Does any of this sound familiar?

You say your original compressor “went out” . . . care to provide us with some more details?

A compressor can stop working intermittently if the refrigerant is low. That will be caused by a pressure switch in the system.


What jmcarc said; have someone put some gauges on the ports and see how much R134a is in there. Since it works intermittently maybe you can get away with filling it with a can, get the stuff with the stop leak in it.

Yup… @jmcarc sums it up basically… What you are describing is the AC compressor “cycling”

Cycling occurs when you are losing AC pressure of the charge. The system will not turn on if the AC charge is not at a specific pressure PRIOR to engaging the Compressor…and there is a sensor to detect this. The sensor will stop the compressor clutch from powering up if the pressure is too Great…and or Too little.

In your instance…since it was working…it is more than likely due to pressure Loss… You are on the bleeding edge of having the correct pressure…so the pressure switch is cycling between Go and No Go…

Get your system evacuated and recharged with sealant at a Professional AC place… Or you can just “Shoot It” with charge yourself…Mixed results with this however…sometimes it works…others it doesnt.

Its best to find a good shop who can ID the leak…fix it…recharge the system… This cycling and how you fix it will determine how long your compressor has to live… The system has AC gas…AND lubricant in it…if you lose lubricant along with the gas…and only replenish the gas…youre in for trouble. Best is to have it properly repaired evacuated and recharged…it is best for all parties involved really…it takes specialized equipment to do this properly…which is why a good AC specialist is key here…


Not knowing what the high and low side system pressures are makes it near impossible to begin making guesses.

If you paid someone to install the compressor then what do they say about this?

There are also other factors such as whether or not the correct amount of oil has been used, whether or not the accumulator or drier has been replaced, if the system was evacuated or not, and so on.