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brian0918
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Post by brian0918 »

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Last edited by brian0918 on Tue Mar 10, 2026 7:39 am, edited 1 time in total.
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Cusser
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by Cusser »

Did you add 19 oz. refrigerant? That's what I see online. Because 110 psi on high side is real low. Didn't the "shop" that added refrigerant and checked for leaks realize that 110 psi was way too low and investigate ????
brian0918
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by brian0918 »

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Last edited by brian0918 on Tue Mar 10, 2026 7:39 am, edited 1 time in total.
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bohica2xo
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by bohica2xo »

Put your gauges on it.

Full load test

Doors open, cabin fan on highest speed. Run the engine RPM @ 2000 for one minute to stabilize, and record pressures while at 2000 engine RPM.

Post the readings.
mk378
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by mk378 »

Pressure equalizing slowly at shutdown means that the expansion valve is closing like it should in that case. If it were stuck open, the pressures would equalize rapidly.
brian0918
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by brian0918 »

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Last edited by brian0918 on Tue Mar 10, 2026 7:40 am, edited 1 time in total.
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bohica2xo
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by bohica2xo »

That compressor is worn out.

I guess the 5k machine missed that part.
mk378
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by mk378 »

...If the machine and operator can be trusted to put in the right amount of refrigerant. Ordinarily, seeing pressures like 90 / 15 the first thought would be "badly undercharged."

Seems really weird that the high side goes up when cut off. I wonder if anything was measured properly.

You may have a bad TAO sensor, I don't know how that would affect the rest of the system. It looks like the 4 cylinder anyway uses a conventional constant displacement compressor with "bang-bang" control via the clutch.
brian0918
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by brian0918 »

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Last edited by brian0918 on Tue Mar 10, 2026 7:40 am, edited 1 time in total.
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bohica2xo
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Re: Diagnosing expansion valve stuck open vs faulty compressor?

Post by bohica2xo »

A 10 psi shift in pressures at 2,000 engine rpm means the pump is not moving much volume.

If the system was under charged, I would expect to see the low side drop quite a bit - even into vacuum if not equipped with a LPCO.

You can add a few ounces of refrigerant and re-test if you are still unsure.

The pressures went up after shutdown from heat soak. Just static pressure change with temperature.
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