AC not working

blackbolt2003

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My 2003 Lightning has about 70k miles on it. I bought it last fall and the ac worked fine. When I tested it out last week I don't get any cold air. It doesn't even "feel" like the compressor is running. Is there anything easy I can check before I take it to the shop?:shrug:
 

Ralph50

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Being from Illinois I guess you haven't used it all winter as opposed to us down here.

I venture to say that you are low on freon. My L goes through about a can of freon every two years and has 90,000 miles.

It will cost you 10-15 dollars to buy the freon that comes with the hose that attaches to the low pressure side. You can get it any Pepboys etc.

I would try that first and see what happens.

You can also buy or borrow the gauges that will tell you the pressures. The low pressure should be about 35 or 40 psi when the compressor is running.

But since your compressor is not even turning on go ahead and put a can in.
 

BT2001SVT

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Yeah definitely refill your freon. The compressor has a ("fail safe" if you will) where if the freon is low, the compressor will shut off so it doesn't burn itself up. I'm assuming that this is why you don't hear the compressor running. The compressor will turn on when you first turn on the AC, but as soon as it notices that there's little or no freon, it will shut back off. The compressor will continue this cycle until you get the freon refilled.

This should resolve your issue.

BT
 
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blackbolt2003

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I must have a leak. I put a can of freon in about 2 weeks ago. Yesterday I turned on the AC and it's hot again. Should I try to fix the leak or just take it to a shop?
 

Gringoloco13

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can someone post a pic up of the line that you need to refill your system with? I checked under the hood, but I want to make sure I am going to put the freon into the right one.

Edit: sorry for the dark picture, but this is the only port I can find on the a/c system that is visible to me. The line running to it states a/c and it has a screw cap. So the area circled and has the arrow pointing to it, is this the low pressure a/c port? It is just to the right and in between the battery and the windshield washer jug.

GetAttachment.gif
 
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blackbolt2003

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NO, that is the high pressure side. The fitting on the freon can will not fit and it's a good thing it won't.

The low pressure side is directly toward the cab(from the one you pictured above) and sort of hidden under a black plastic...thing. It's not hard to find if you are looking for it.


Edit: wait a sec..that's not a lightning. What is it?
 
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Gringoloco13

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NO, that is the high pressure side. The fitting on the freon can will not fit and it's a good thing it won't.

The low pressure side is directly toward the cab(from the one you pictured above) and sort of hidden under a black plastic...thing. It's not hard to find if you are looking for it.


Edit: wait a sec..that's not a lightning. What is it?

I forgot I had a service manual and figured it out last night, but you are correct thanks for the post! It is a Lightning, here is a older shot of the engine bay during the day:

DSC04791.jpg
 
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Gringoloco13

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I must have a leak. I put a can of freon in about 2 weeks ago. Yesterday I turned on the AC and it's hot again. Should I try to fix the leak or just take it to a shop?

Did you measure the amount of freon in the system with a gauge? Mine was almost empty and 2 lbs filled it up about 3/4. But never put freon in without a gauge to monitor how much is in the system. Have you tried the freon with the sealer mix in it? If not get a kit with a gauge and put one can regular and one can with the sealer in it. If that doesn't keep it from leaking then you will need to put the uv dye in the system and find the leak with a uv light. Take the system apart and replace the faulty o ring, etc. If you don't have any knowledge of doing this though, I would have a shop do it. I have done this on one of my old cars and it can be a real pita, and that is why it costs so much at shops.
 

Robert Francis

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This is one of those jobs that if you have expertise in, you may work on yourself seeking the leaking area(s). If not, you're probably better off taking it into a shop that does a/c work.
 

04mellowyellow

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I just ran a test with my gauge on the side you fill with the R134a and when the compressor is running it drops down to 25 psi before the compressor turns off. Once the compressor turns off the needle floats to 45 psi before the compressor turns back on. I ran a digital thermometer right at the vent opening in the center of the dash and the lowest reading I get is 40.1 degrees. The cycle on to off takes about 15 seconds before repeating the process all over again.

EDIT: My L is a 2000 with 89K miles and I bought it used. Someone mentioned that it should read between 35-40 psi with the compressor running. Does that mean I'm running low?
 
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JollyGiant

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Yes, if it pulls down to 25 psi you are low on freon. There is a pressure sensor which detects low pressure and shuts off the compressor when it detects the pressure going below about 32 psi.
 

04mellowyellow

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Put a can in it and now it holds at 35 psi when the L is at idle. When I rev the engine and hold the rev for 10 plus seconds it will drop down a few psi and cut the compressor off for a few seconds. Is that normal?
 
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