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A/C compressor working, but working intermittently when jumped from hi

zeater04

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zeater04 Enthusiast

zeater04

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Ok well to begin with my A/C compressor has not been turning on so I'm only having warm air blow out the vents.(Not to mention I live in FL). After doing some research I checked all fuses, the relay and and the A/C switch on the dash. So my next step was to jump the high pressure switch under the hood and what do you know the a/c compressor kicked on. The problem that I'm running into now is while the compressor is jumped from the high pressure switch the compressor turns on and off intermittently with still warm air blowing out of the vents even for the short time the compressor is running. Is the any way to power directly to the compressor to eliminate an electrical issue or is the any other diagnostics I can preform? Thanks for all the help!!

zeater04 Enthusiast

zeater04

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Or maybe I jumped it from the low pressure switch. It was the switch that was connected to the canister.

muddkatt Senior Enthusiast

muddkatt

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Check the pressures with a gauge before you begin forcing the compressor to run. Report back with your readings.

zeater04 Enthusiast

zeater04

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My main concern was that the compressor was shot but if its working when its being jumped that means its still in working condition right? It was just filled with R34 and couple months ago. What should my pressures be?

muddkatt Senior Enthusiast

muddkatt

Posted
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Why was it recently filled? Sealed system that has no leaks should never need any freon added.

Pressure with the compressor NOT running should be at least 85 PSI. It takes about 30 PSI on the low side to keep the compressor engaged. By jumping the low side pressure switch, the compressor will run, but it will not cool if there is no freon.

muddkatt Senior Enthusiast

muddkatt

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Let me add that the compressor could be "shot", but the only way to tell is to look at the pressure readings.

zeater04 Enthusiast

zeater04

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Well i refilled it until the gauge on the can from autozone went to the red and it wouldn't take anymore. Thats when i discoverer the compressor was not running. I refilled it because it wasn't blowing cold and thought it just need to be charged because the truck was sitting for about 7 months

Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted

Slow your roll man. Don't run your pump like that. It needs to come on properly and should not be jumped. That being said, if you want to keep the pump running all the time, just run a 12V power wire directly from the battery to the + wire going into the A/C pump. Ideally you would want to run the wire from a source that only supplies power when the rig is running. The pump itself is controlled by the clutch. The clutch is controlled my an electromagnet. The electromagnet is controlled by that 12V+ lead. >>> Don't run your pump like that !! <<< If you run the pump "dry" its going to fry it, and then you will have to fix that too. I am confident that you will be able to fix the actual problem with the help of this forum. These guys on this forum are pretty knowledgeable about cars. You came to the right place for help. I am not allowed to tell you how I would fix it, or the admin will delete the information. I was never forbidden to share a link from this website though. It will provide you will everything you need to know to fix your A/C. Please read the entire thread before starting the repairs, because there are differences of opinion on the matter. You be the judge.

 

Anyway, good luck on your repairs - and don't give up! You can fix it.

 

Here is the link to the other thread: http://www.gm-trucks.com/forums/topic/202595-ac-compressor-wont-kick-in-except-on-defrost/

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Pressure at rest for r134 varies by temperature. For our typical warm weather problem window, pressure would be 70-100.

 

Running compressor and no cold result could be a) low freon, b) blown compressor, c) clogged orifice which would create high pressure at the compressor.

 

Only way to diagnose is with a full set of guages.

 

Sent from my XT1053 using Tapatalk

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