AC help please its hot!

DR809

Member
Ok so the AC on my s13 blows cold when I turn on the car & ride for like 15-20 mins. Then stops blowing cold air. Does anybody know what the problem might be? The ac button light turns off when is pushed in, I was thinking maybe its the control unit?
 
you might have too much freon in it, the ac system works off of pressure, and if there is to much the pressure switch trips and it shuts the compressor off.


You need to put gauges on it and check your high and low side pressures.
 
It's most likely you orifice tube/expansion valve being clogged. When the ac system is first turned on, it allows refrigerant to flow through. As is gets colder, the orifice tube/expansion valve being clogged holds some of the debris in your system. It freezes the debris and restricts refrigerant from flowing. Now if you turn off the system, and let the debris melt. It should work perfect, but if you turn it on for a while it will just freeze the stuff again.
 
It's also possible that the system is not cycling off properly and it's turning the evaporator core in the dash in to a large block of ice which won't allow airflow properly.

You really need a set of gauges on the system to tell best but you could at least put a digital thermometer in the center vent and turn the a/c to recirculate (Max A/C), temperature to cold and the blower speed to the lowest setting.

This will cause the compressor to cycle off and on the most as well as get the evap core as cold as possible. From there you can check the operation best.

Situations like what you're describing can be caused by a bad pressure switch, evap freezing up, compressor clutch gap being excessive and the magnet eventually can't pull it in, or a random issue such as wiring.

If it gets as cold as desired (or better) then you can almost rule out the charge level. Sitting still, if it's overcharged then your system should shut down within a matter of minutes since the pressure climbs pretty quickly. If it's low then your compressor would cycle off and on rapidly AND you wouldn't have the cold temperature at all.
Doug
 
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