A/C working improperly

A/C condition is sometimes working and sometimes not working. This
happening is keep repeated back and forth everyday. Usually, When a
engine is cool,it does work great. But it is not working(blowing warm
air)as soon as engine is gets hot after about 20 to 30 min with driving.
I took my car to a mechenic checked A/C gas and performance. It's o.k.
everything is fine. working great. It's very cold. When I got it back
to my home, problem starts again. Is something a relay problem or
somthing else? What is going on?

 

It sounds like it might be icing up. When it starts blowing warm, pull over
and open the hood look at the A/C lines. If you see ice building up on them
(usually at the point where they go into the firewall), that's your problem.
The system is not properly charged.

If not ice, then probably the sensors that cause the compressor to stop when
there is either too much or not enough pressure in the lines are engaging.
Same problem - system not properly charged.

There is a tendency to overcharge R-134 systems. Have you recently had it
serviced?

 

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It sounds like he overfilled it. The system will stop the compressor for
too low pressure, and if it goes too high. Might be why it works OK
until it warms up.

'Curly'