I recently installed a new A/C compressor, orifice tube, dryer and high pressure and low pressure hoses. Everything worked fine for about a month. Now the system blows very cold then starts getting warm. I swith to vent and it gets cooler then switch back to A/C and it gets icy cold for a mile or two then starts warming again.

My question is...could it be the pressure switch?...Low on freon?...too much freon???

 

I dont know the exact cause of why but I believe the evaporator or expansion valve isnt working properly.What type of freon does the vehicle us 134A or R12?I know the older R12 systems can freeze up if the presure isnt what its supposed to be,If its too low the system will freeze..I used to work on air con systems longtime ago so I dont remember everything.Get a guage and check what the presures are and the how much freon is in your system.On the presure you have a high and low side.Simple salution is when you notice the system freezing put the system on vent and turn of the ac till it unfreezes.

 

Thanks for the reply...The system uses 134. I'll borrow some gauges and check the pressure. The expansion valve is the same as the orifice tube...is it not?

 

Good forum, remember there salespeople, but lot's of good info. Expansion valve and orifice tube are not the same. They preform the same function in different ways. Our trucks use orifice tubes.
If it worked OK for a month you most likely have a leak, couple of different ways you can get some UV dye in and look for it. Freeze up evap is one sign of low refrigerant.
Automotive AC Information Forum - ACKITS.COM

 

yes I believe you would have one or the other....I can't remember any vehicle having both off the top of my head. When you hook up the manifold (gauges), don't open the valves at the manifold to be able to read pressure and if adding freon through use of manifold only open low side.

 

Thanks guys...i will report back what I find.