Air conditioner mostly only works from a cold start

2006 AUDI A3
94,500 MILES • 2.0L • 4 CYL • 2WD • AUTOMATIC
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PALBAL7
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The original air conditioner was replaced at 62,000 miles by Audi by the the original owner, not me.
Now the A/C works mostly on cold starts with outdoor temperatures in the 80's. Any warmer and it just doesn't work.
Last week I left the car running a few minutes while in park and when I jumped back into the car cold air was slightly oozing from the vents with the fan on low. That was the only time that it has happened. I know there are no leaks. I hope you can help.

Thank you.
Jun 3, 2020 at 8:41 PM
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KASEKENNY
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Can we step back and clarify how you know there are no leaks? The most likely cause of this is low refrigerant. If we didn't find any leaks, can we hook up a gauge set and find out what the pressures are when the A/C is on?

If you don't have a gauge set, you can get them from a parts store that rents tools. This way you don't need to purchase them but we can find out what the high and low side pressure is. Let us know and we can go from there. Thanks

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system
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Jun 4, 2020 at 12:33 PM
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PALBAL7
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I do have gauges and it is not low on refrigerant. Could it be the high pressure sensor or something else?

Thank you for your time!
Jun 4, 2020 at 1:14 PM
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PALBAL7
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Or maybe A/C Compressor Control Solenoid Valve ?

Thanks again.
Jun 4, 2020 at 1:25 PM
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KASEKENNY
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It could be depending on what the actual pressures are. What is the high and low side pressures when the engine is off, and when the engine is running with the A/C cycling?

So you should get three sets of numbers.

Engine off high side:
Engine off low side:

Engine running, compressor off high side:
Engine running, compressor off low side:

Engine running compressor engaged high side:
Engine running compressor engaged low side:

Let me know these PSI readings and that should tell us what direction to go. Thanks
Jun 5, 2020 at 8:43 AM