Refilling AC on 1998 GMC Jimmy


Old 05-29-16, 07:37 AM
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Refilling AC on 1998 GMC Jimmy

Last year I used the an over-the-counter air conditioning refill system on my car. As dumb as I am, when it comes to cars, I found it very easy, and my air is very cold. But this is not a commercial for the product.

I had only used half a can, and so this year, when my wife's truck was blowing hot air, I decided to add the rest of my can, and if necessary, purchase another can to finish off the job.

Well, what's happening is that I adjust the dial on the pressure gauge to the outside temperature and start the car and put on the air, as the directions indicate.

What's happening is that the compressor is kicking on and off every few seconds. The needle on the gauge will rise until it gets right on the border between the Green & Red zones, then the compressor will kick on, and the needle drops down very low, into the white. Two seconds later the compressor turns off, and the needle starts rising again. This goes on and on.

I've read that the compressor will not run if the coolant pressure is low, but I'm afraid to add more, because the can stresses not to overfill, and I'm not sure if I should be reading the pressure at the high point or the low.

Is there a problem here? Is my compressor not acting the way it should? Is this problem over my head and I should bring it in for service?

Thanks for your time!
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Old 05-29-16, 09:04 AM
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It sounds like you have a leak in the system. Time to get it fixed.
Old 05-29-16, 10:22 AM
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Your system is low on refrigerant and obviously has a leak in it.
Old 05-29-16, 11:42 AM
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AC comp will NOT turn on below specific factory preset system pressure. So, if it engages, you do have at least minimum pressure present.
The only true way to diagnose the system is with gauge set. So is to refill it. Gauge set is rather inexpensive from Harbor Freight Tools. Very handy.
Why a year old can that likely has no pressure left in it anyway is doing what it's doing is anyone's guess. It is absolutely unscientific tool.
Old 05-29-16, 05:08 PM
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sounds like the system is very low on Freon so just filling it would likely just leak out the Freon you added in a very short amount of time leaving your a/c not working again.
would see a shop for diagnosis and estimate on repairs you could then have the shop repair it, or have them evacuate the system and do the repairs yourself, but you do need some basic tools for a/c repair like a set of gauges and vacuum pump and can tap to be able to pull a vacuum on the system after repairs and to fill with Freon. in some cases it may be worth investing in the tools if you feel that you can do the repair yourself, but for many its best left for a shop to repair.
Old 05-29-16, 07:35 PM
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Thank you all.

Well as I was filling it, the needle WAS going up, but as I said, I don't remember the compressor kicking on and off like that when I used it in my car last year.

I don't mind bringing it into the shop if I have to, but I'd feel stupid about doing it if I'm halfway to filling it myself and don't even know it.

Maybe I should wait a few days, hook it up again and see if the pressure has dropped off?

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