My AC is turning on and off, most notably when the car is stopped, the AC will turn off/stop working (warm air will start coming out). Then, when I start moving, the AC will get cold again. I believe the compressor is turning off for some reason. I made sure the system is charged (not overcharged, the guage is in the middle of the blue section on the guage). Why would this be happening?
What is happing the freon in your ac system is low which means your low pressure switch in the ac system is doing its job . It's turning on and off , when pressure builds up the compressor come on .
I really don't think thats the problem because like I said in the post I checked the pressure in the system with a guage and it is within spec's. Actually, when I charged the system a week ago with freon, I kinda overcharged it, and when I did the compressor was doing just what you say, but probably because to much pressure was building up and not because there wasn't enough. I then let some freon out so the pressure dropped and then the AC started working...but i'm still having this little problem of the compressor turning off when I stop.
Have you noticed any shaking or anything like that? My Honda shimmys like a bish at a stop with the a/c then eventually turn off on high pressure...seems to be a condensor fan. So check your con. fan and make sure its coming on when you have the a/c on.
My AC is turning on and off, most notably when the car is stopped, the AC will turn off/stop working (warm air will start coming out). Then, when I start moving, the AC will get cold again. I believe the compressor is turning off for some reason. I made sure the system is charged (not overcharged, the guage is in the middle of the blue section on the guage). Why would this be happening?
I'm having this exact same problem with my 2000 Altima. I also guaged the pressure and got a good reading. Did you try the pressure switch?
What year is your Sentra? You need to have a AC gauge hooked up at the time that the problem is happening to see exactly how high the pressure is getting in the system.
It doesn't matter if the pressure is shown as OK while sitting still. If you got some sort restriction in the line, it may exhibit the symptom you are explaining.
Also, are you sure that the freon you used is the correct one? Not the store bought kind you can add with a can? Some of those contain the wrong kind of oil and aren't quite compatible.
Another thing is the ECM, or the engine control module. Some Sentras the ECM sends the AC signal to the compressor. I have seen a couple of Sentras with bad ECMs causing the AC to not work properly.
Overheating will also create the same symptoms. If you are just sitting there and the fan isn't working, car starts overheating and the AC stops working. Once you start moving, car starts to cool properly and the AC starts working. (thats just a quick explaination)
But like someone said earlier, you need to have it properly diagnosed with the proper equipment. There is just too much information missing here.
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