Air Cond. blows ice cold, then warm and humid

[ford91]

My 91 a/c blows ice cold, but then blows tepid and humid. Then it will start blowing ice cold again. This happens at highway speeds and just around town. I know a/c can get warmer at a stop because no air is passing via the condenser. If any one has had this problem and knows how to fix it, I would be very grateful, as we live in Las Vegas!!
Thanks in advance....Eric

 

[SiLenZe]

its cycling on and off. you get the same effect by switching from ac to panel.

 

[newbi]

Yeah , its cycling ,and it sounds like its cycling on low pressure cutout due to low refrigerant charge. Start looking for a leak aound compressor line attachment(O rings go bad) and at all other joints.

 

[wpurple]

I would guess that it is the thermostat. If it is blowing cold air then most likely you have enough freon.
Is there a sight glass on the accumulator? If so check for bubbles.

 

[Glacier991]

There are several possibilities. Most involve your state of charge. Get your charge checked. ANother involves the low pressure cutout. If it has failed, you could be freezing your evaporator. Air will be colder than h*ll a while and then not. Charge will show up in compressor cycling. See if you have compressor cycling excessively. If not, My money is on your low side cutout.

Happy Exploring.

Chris

 

[piperdad]

mine was doing the same, the clutch cycling pressure switch was failing intermittently. try using a jumper wire to short out the plug to see if the compressor engages and you get cooling. took $35 Canadian and 2 minutes to return to the ice cold