Question A/C acting Funny.

[platinum01]

It started about 2 weeks ago I was driving home from work and sitting in Houston Traffic the A/C started blowing hot air. Once I started moving at posted highway speeds it cold back down and started blowing cold again.

Went to work the other morning and the Air was blowing out of my defroster vents even though the knob was on the dash vents. Went and had the system checked added to cans of R134A and a can of oil. Worked fine but now is starting to get hot when not moving.

What should I do now? I am thinking of running the leak detector threw the system now.

 

[Kevin Angstadt]

Sounds to me like you have a bad selector switch or a vacuum problem. The last time I had the air go out the defroster when on the dash vents it was the selector switch.

 

[JLDickmon]

well, you got two problems, mi compadre..

first... hot in traffic, cooler down the highway..
you've a refrigerant problem on your hands..
whether it's low (did it get any better when you put the hand grenades in it?)
wet (dessicant in the accumulator is waterlogged)
or is leaking (yeah, you should have put the leak detector in before the refirgerant)
I can't tell because I have no idea what the pressures are.
Does your local AZ rent gauges?

secondly... blows only through the defroster
you have a vacuum problem
does the pump work? It should run for a few seconds when you flip the key on
or, just unplug the vacuum harness from reservoir with the key on and it should come on by itself.

then run the vacuum line to the a/c control... make sure it's plugged in to the splitter behind the glovebox, and secured to the back of the switch..

if all is well, start the truck and listen for the sucking sound from the switch..

I'm thinking you'll have found it by then..

 

[platinum01]

The little vacum pump works just fine. It runs for days. But now that I added 2 cans the pump runs for a few seconds and then off. I was wondering if this was like a default.

I am going to run some leak detector if the system runs low again. I don't know anything about A/C guess I'll have my father in law look at. He owns a A/C and Refridgeration company.

 

[JLDickmon]

The little vacum pump works just fine. It runs for days. But now that I added 2 cans the pump runs for a few seconds and then off. I was wondering if this was like a default.

I am going to run some leak detector if the system runs low again. I don't know anything about A/C guess I'll have my father in law look at. He owns a A/C and Refridgeration company.

one should not have anything to do with the other...
if your truck is 4WD, this vacuum pump runs the hubs as well.. if it runs a bit & shuts off, this is normal operation
did you run the lines to the axles and make sure they're not rotted to pieces?