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Air conditioner

when i start out in the morning for work, my air (i live in fl) is working fine, also for the 20 min.trip…however, when i need to use the car perhaps a few hours after the, the air blows warm…sometimes it kicks in to cold for about 30 seconds, then back to warm on all levels of the blower…sometimes if i open the back windows a bit, it will come back on for a few moments. i do hope this is not going to be a major repair, as it’s a 2000 Nissan, but has served me well. it hasn’t any vapor or fluid coming out under the dash, which happened to me when I owned a Ford Escort wagon, which cost a few dollars to repair…the compressor, i think?? any ideas?? thanks in advance

I think you are probably low on refrigerant… If you want to do it the cheap way go to walmart or any automotive supply store. Get a can for R-134 with a gauge on it… They are about $25… Follow the directions on the can and you should be good to go…

I don’t think it is your compressor, since you do get cold air some of the time. There are switches, relays, thermostats, and sensors that feed information to the air conditioning controls. Your car might be overheating, and killing the AC to prevent more overheating. Just one possibility. In FL you have lots of good AC repair places, time to find one and see what the problem is. I won’t expect a mega expensive repair bill on this one.

It could be simple. Low refrigerant will cause the pressure switch in the AC to stop the compressor. Enough pressure of coolant will fix this. So you can add a bit of walmart refrigerant. But a good shop will give your car a look over and see if there is another problem as well. They might also create a big bill for this, so go to a recommended shop you can trust to do only what you need.

Since it works properly for the first commute of the day, it may not be low on refrigerant. When it cuts out, you should pop the hood and see if the compressor is engaging at all, or if it’s “short cycling”, or cutting in and out rapidly. If it is cutting in and out, it may be low on refrigerant, but if it just isn’t coming on, you likely have a different problem.

I think it might be an electrical control or pressure switch, such as your ‘clutch cycling switch’ that’s failing, assuming your vehicle uses one. I had erratic operation with the A/C on my old car some years ago. After some head scratching, I figured the clutch cycling switch was sticking open when it heated up. A new sensor and problem solved. You can also try swapping the A/C relay with one for the cruise control or similar, assuming they’re the same part, to see if it affects the problem.