Weird AC problem

[Echomirage]

ok, thanks guys. it sounds to me like its the core freezing. it would make sense....itll work for a while, then freeze up and block airflow. i shut the AC off, which would redirect air away from the core....itll thaw out, put AC back on, and repeat.

also, what i forgot to add in the OP, is i was getting condensation dripping inside the truck, passenger footwell area. so it really sounds like a frozen core.

the fix would be to clean the motor/core area, unclog the drain hose, and possibly the cycling switch?

 

[chipskittles]

well, the dripping inside the passenger footwell is pretty common and will probably still happen even after you have fixed this problem, especially if you live in a humid area. Not saying you should not do everything recommended, just tempering expectations...

 

[Shaun Anderson]

The cheaper versions of the switch mentioned are partly to blame for evaporator freeze over. They don't cycle the compressor at the proper pressures, due to not being made to proper specs. Spend coin on one from the dealer and if the system has the right amount of refrigerant in it the freeze over will likely go away.

 

[chipskittles]

The cheaper versions of the switch mentioned are partly to blame for evaporator freeze over. They don't cycle the compressor at the proper pressures, due to not being made to proper specs. Spend coin on one from the dealer and if the system has the right amount of refrigerant in it the freeze over will likely go away.

Agreed- been there. You can get the oem AC Delco part on Amazon, don't have to go to dealer

 

[someotherguy]

Dripping on the floor can also be the evaporator core drain tube clogged up. It exits the firewall right next to where the heater core hoses pass through; it's a black plastic nipple and may or may not still have a rubber elbow on it. If it's there, the elbow just slips right off and you can clean the tube out by gently pushing through with a stiff wire. Just go straight back and forth and you won't hurt anything.

BTW turning off the A/C does not redirect airflow. All air in the HVAC system passes through the evaporator core, whether in vent, A/C, heat, defrost mode. The reason it thaws out is simply because warm outside air is now hitting the frozen core and thawing it out. When enough thaws that air can pass through it again, you'll get momentary cold air even with the A/C function off, because it's passing through what remains of the ice until it's all thawed.

Richard

 

[Echomirage]

BTW turning off the A/C does not redirect airflow. All air in the HVAC system passes through the evaporator core, whether in vent, A/C, heat, defrost mode. The reason it thaws out is simply because warm outside air is now hitting the frozen core and thawing it out. When enough thaws that air can pass through it again, you'll get momentary cold air even with the A/C function off, because it's passing through what remains of the ice until it's all thawed.

Richard

thats basically what i meant but didnt type out exactly what i was thinking.

rock has a delco switch for $15, four seasons for 11, GPD for 7, and another delco for a 134A retrofit for $23. youre all saying the regular delco is the one to get?

 

[chipskittles]

thats basically what i meant but didnt type out exactly what i was thinking.

rock has a delco switch for $15, four seasons for 11, GPD for 7, and another delco for a 134A retrofit for $23. youre all saying the regular delco is the one to get?

I believe the AC Delco part you want is the Black one. The purple may work but I think it's intended for converting R12 systems to R134A

 

[Shaun Anderson]

White is for R12. Black is for R134A. They are not interchangeable.

 

[GMCTRUCKS]

Did you check if your low on Freon?

 

[Echomirage]

it didnt have any leaks when the shadetree mechanic did the AC. it still blows cold, and he topped it off with another half can the last time he messed with it.

besides all that, i drove it yesterday, and now im not getting any air out the vents at all, with or without AC on. i get defroster, floor, blend, and thats it. nothing out the vents at all.

the air door actuator, or whatever its called, is new. could there be a vacuum leak somewhere, thats causing the no vent issue?