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AC problems


justin0469

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96 Chevy 2500HD (4.3L V6 from a 1500 though)

AC blows warm air

The AC compressor only comes on when I jump the low pressure switch. I've charged it with like 3 of those R134a cans but no luck. I replaced the low pressure switch and after putting the last can in, I see a little bit of something dripping from what looks like an overflow tube underneath the AC accumulator coming out of the firewall. The fluid is a little oily and I suppose it could be the R134a fluid stuff but the overflow tube comes out of the firewall and I can't tell where it's coming from. I assume I have a leak somewhere but I'm not sure where or how to find it.

Any help?

Edited by justin0469
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96 Chevy 2500HD (4.3L V6 from a 1500 though)

AC blows warm air

The AC compressor only comes on when I jump the low pressure switch. I've charged it with like 3 of those R134a cans but no luck. I replaced the low pressure switch and after putting the last can in, I see a little bit of something dripping from what looks like an overflow tube underneath the AC accumulator coming our of the firewall. The fluid is a little oily and I supposed it could be the R134a fluid stuff but the overflow tube comes out of the firewall and I can't tell where it's coming from. I assume I have a leak somewhere but I'm not sure where or how to find it.

Any help?

my hvac guy at work uses a uv dye in the refrigerant to locate a very slow leak.

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the freon stuff is oily - it could very well be that

also, after fixing the switch, have you checked the level of the freon?

a guy at work this morning said his ac blows warm and that he just charged it....i hooked up the gauge and it was all the way in the red....i put on a thick glove and released some of the freon (just kidding...i used the proper EPA approved method of getting rid of it) and after draining a BUNCH of it out, the gauge was reading in the "charged" area and the ac was ice cold

3 of those cans is probably way too much....too much freon will make it blow hot air just the same as having none

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sounds like the condenser drain tube.......although it should just be water.

agreed...ive never heard of an overflow for refrigerant... i could be wrong, i havent messed with hvac stuff too much (just what little hands on i had at cscc)....but he mentioned it being oily, and freon is very oily - made a mess with some today lol, it feels the same as that white lithium aerosol grease

Edited by Steve Butters
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agreed...ive never heard of an overflow for refrigerant... i could be wrong, i havent messed with hvac stuff too much (just what little hands on i had at cscc)....but he mentioned it being oily, and freon is very oily

i havent done much either. i just thought maybe his condenser box was a little funky or something. or the condenser might have a leak and thats why it was low in the first place. ugh.

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i havent done much either. i just thought maybe his condenser box was a little funky or something. or the condenser might have a leak and thats why it was low in the first place. ugh.

assuming it was low....a lot of people dont pay attention to the gauge and they just start adding refrigerant (not saying he did, but it happens - thats what my friend did)....and he said some switch had to be replaced also, but he did that after adding a ton of freon, so if the switch was the initial problem, then his current problem could be too much freon.... the truck i was working on today called for 27oz of freon, and the can he had was an average size can and had 18oz... 3 of those cans plus whatever was in there would be way too much for any vehicle im guessing....unless its leaking like crazy, its probably got too much freon in it, so no matter what parts gets fixed etc he should hook up a gauge and check the level first and release some until its in the green again and then go from there....if its low (low on the gauge, not just blowing hot), even after 3 cans, then get a dye and find the leak...it will be a big leak and easy to find

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3 of those cans is probably way too much....too much freon will make it blow hot air just the same as having none

I agree. I was watching the gauge and it never really went up that far and after each can was empty it slowly but steadily dropped back down to nothing. I went out there just now and used a punch to push in the pin on the low side valve to see if I could let some out and nothing came out whether the truck was running or not, whether the low pressure switch was jumped or not. Seems as though it's not keeping pressure, indicating a leak still I suppose, unless I'm just doing something wrong. The fact that I replaced the low pressure switch (it was pretty bad) and the compressor still doesn't turn on without me jumping it also indicates that. :/ gay.... I'd like to have this fixed before Thursday morning as I have to drive it to South Carolina and back to help my sister move :(

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HOLD UP!!!

It sounds like you need an evaporator. If what you are getting out of the drain that's on (or near) the firewall is anything but water, that's a problem.

Now a few things that need to be cleared up that might help you out.

Refrigerant is not oily. There is oil in the system that travels with the refrigerant, and it will leak out with the refrigerant. This is how the dye works. The dye is in oil, and will leak out with the refrigerant.

The evaporator is what does the cooling, it is under the dash. The "restrictive device", expansion valve or orifice tube is right before the evaporator. a The condenser is out in front of the radiator, and the airflow across it will remove heat from the liquid refrigerant.

Next, just recharging to a pressure on a gauge is not going to get you a proper charge with a R-134a system. In the days of R-12, that worked, but not anymore. With a R-134a system, you really need to have the system empty, then add the proper amount of refrigerant, by weight.

The R-134a is not Freon. Freon is a brand name (I believe Dupont) for R-12.

I'm not trying to bash what anyone has said here, just trying to educate!

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looks like Judd is here to save the day!

and wow Judd thanks for the refresher...i completely forgot about the oil being separate from the refrigerant...its been about 4 years since i took that HVAC class lol

and when i mentioned freon, i just meant the stuff you buy in the can at autozone - whatever brand, not exclusively one kind...kinda like when people say "kleenex" when they mean tissue

Edited by Steve Butters
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If it's leaking out fast enough that you can see the gauge going down (without the compressor running) and you don't see a cloud coming from somewhere under the hood, you probably have a cloud of refrigerant coming out the vents! The oily stuff coming from the evaporator case is a really good sign as well.

When a leak is big enough that the gauge drops, you should be able to see it!

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looks like Judd is here to save the day!

and wow Judd thanks for the refresher...i completely forgot about the oil being separate from the refrigerant...its been about 4 years since i took that HVAC class lol

The important part of the oil being separate from the refrigerant is that once it leaks out, it needs to be replenished!

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Also, I only see one port. Where is the high side port?

Any number of places. But most likely up by condenser. Will likely be on Smaller diameter lines.follow the lines coming off the condenser.

Sent from my iPhone using Tapatalk

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