AC not cooling

2010 FORD MUSTANG
150,000 MILES • 4.0L • 6 CYL • 2WD • AUTOMATIC
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RONNIE BUSHA
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I have replaced the relay, drier, and high and low side valves. It has low pressure on the high side, and high pressure on the low side. Sometimes it will work for a twenty minutes or so, but most of the time it will not cool at all. Could this be a compressor issue?
Jun 30, 2018 at 5:43 AM
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ASEMASTER6371
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Good morning.

What are the exact pressures while running?

Does the compressor engage when you turn on the AC?

Are the pressures equal when the AC is not on?

Roy

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak
Jun 30, 2018 at 5:55 AM
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RONNIE BUSHA
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I do not know the exact pressure, all I have is the gauge on the fill can, but it always pegs it in the red.
The compressor does not engage, I have jumped the low pressure relay and it will engage then, but otherwise no.
Yes, the pressure is always reading high in the low side.
Jul 1, 2018 at 4:08 AM
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ASEMASTER6371
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If you jumped the low pressure switch and it comes on, replace the switch. It needs 20 lbs on the low side to engage the relay.

Roy
Jul 1, 2018 at 5:00 AM
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RONNIE BUSHA
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How many lbs. on the high side?
Jul 2, 2018 at 3:36 AM
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ASEMASTER6371
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The high side is a normally closed switch. It will open at 375 lbs to protect the compressor.

Do you have the gauges now?

Roy
Jul 2, 2018 at 4:25 AM
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RONNIE BUSHA
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I will have gauges tomorrow. I have already replaced the low pressure relay also.
Jul 2, 2018 at 10:07 AM
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ASEMASTER6371
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There is no low pressure relay, just the switch.

Did you replace the switch?
Jul 2, 2018 at 10:15 AM
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RONNIE BUSHA
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There was a relay in the fuse box under the hood that I could jump with a wire and the compressor would start running. That is the one I replaced.
Jul 2, 2018 at 10:28 AM
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ASEMASTER6371
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That is the clutch relay. Jumping it does not mean it is bad. It means the control side was not grounded by the PCM because it did not see the proper signal.

Roy
Jul 2, 2018 at 10:39 AM
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RONNIE BUSHA
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Okay, I got some gauges. At a idle with the AC turned on high, the compressor will not engage and the pressure is 90 lbs on both the high and low side. When I jump the relay and start the compressor the low side drops to 40 lbs and the high side will climb to 325 lbs at that point the fan on the radiator will turn on when that happens the low side drops to 10 lbs and the high side drops to 125 lbs, the the fan turns off and the pressure starts to climb again.
Jul 4, 2018 at 5:18 AM
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ASEMASTER6371
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The low side dropping to 10 lbs is no good. It should be 25-30 lbs and stay rock solid.

You have an issue with that but it will not effect the compressor from kicking on. At 20 lbs the system should kick on by itself.

At the very least, you need an expansion valve and a drier.

You need to test for power to the relay key on engine off. There should be two powers present.

Roy
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Jul 4, 2018 at 5:28 AM