I had the same problem with my 94 chevy C1500 truck about 2 years ago. The air would be nice and cold and than all of a sudden,nothing but hot air. I would than go over to the low pressure switch on the ( I call it the dryer) and wiggle the pigtail connector and the ac clutch would kick in and cold air would start blowing again.
I replaced both the low pressure switch and the connector and its been working good ever since. So, you might be having the same problem that I had and replacing both will hopefully fix your problem. Gumby always gives good advice and is very helpful in this forum.I appreciate all his help along with all the other persons that contribute to giving help.I wish I could help here but I am just a DIY person that does not have much experience in engine work. However I do take all the advice that is given to me here and put it to practice.Its turned out pretty good.

 

@Birdman01 Thanks for the tip! I think I have tried that once, I just can't remember if it woked. Is their a Schrader valve behind that pressure switch? So that I don't have to let all the freon out to replace it?

 

When I replaced the switch,I did not loose any freon at all. You should be ok doing the same thing.

 

Yes there is a shrader valve under the sensor. There will be a minor “pop” and a minuscule amount of refrigerant when the sensor is removed but that’ll be it as long as the valve isn’t stuck open.

 

Thanks @Birdman01 and @Gumby22 !