1992 Nissan Sentra AC works sometimes, other times no

Tiny
MEYERDEL
  • MEMBER
  • 1992 NISSAN SENTRA
Air Conditioning problem
1992 Nissan Sentra 4 cyl Front Wheel Drive Manual

The AC seems to work randomly. When it works, it blows cold. Worked every day for the last two weeks, then yesterday no. When turned on, the compressor engages, slight load on engine, and either blows very cold air, or slightly cool air. I had the system pressured checked, no leaks. Mechanic added more freon, but only took small amount of one can. What else in the AC system can control whether it blows cold or not? A relay? A breaker of some sort?
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Saturday, April 10th, 2010 AT 3:52 PM

5 Replies

Tiny
JACK42
  • MEMBER
If the system is full and the compressor is engaging, it may be an issue with the expansion valve. The expansion valve is a temp controlled orifice that is what creates the cold air out of the line pressure. If theblend door (Temp door) works ok, the expansion valve is the only thing left. Your tech should be able to tell by the system pressures when the system is blowing warmer air
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Saturday, April 10th, 2010 AT 6:46 PM
Tiny
MEYERDEL
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The mechanic seemed more interested in selling me on the conversion idea, especially by the time that I spent the money replacing the old freon.
I don't know if this has any bering on the subject, but when I start the car and turn on the AC, it will either work or not work until the next time I start the car. It never stops working in the middle while I'm driving.
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Saturday, April 10th, 2010 AT 7:51 PM
Tiny
JACK42
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Could very well be the expansion valve.A 134a conversion will be worth it in the long run as well, the refrigerant is less expensive and more readliy available than the R12
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Saturday, April 10th, 2010 AT 8:37 PM
Tiny
MEYERDEL
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Do you know how many cans of freon that system would take? Whether I do the conversion, or replace the expansion valve, it looks like big bucks either way.
When it comes to replacing the expansion valve, are we talking complicated enough to diffinently let a mechanic handle it? I guess there is no easy, or most of all inexpensive way out of it.
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Sunday, April 11th, 2010 AT 12:24 PM
Tiny
JACK42
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The exact amount that would be put back in the system would be determined by the system pressures. Since it needs to be converted, I would have a shop do it. The oil needs to be changed to a different kind and the system needs to be vacuumed down to eliminate the moisture that gathers from it being opened
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Sunday, April 11th, 2010 AT 5:40 PM

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