Page 1 of 2
..........
Posted: Tue Sep 06, 2016 7:15 am
by brian0918
..........
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Tue Sep 06, 2016 7:39 am
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 ????
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Tue Sep 06, 2016 8:17 am
by brian0918
..........
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Tue Sep 06, 2016 10:04 pm
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.
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Wed Sep 07, 2016 7:27 am
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.
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Thu Sep 08, 2016 4:20 pm
by brian0918
..............
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Thu Sep 08, 2016 4:33 pm
by bohica2xo
That compressor is worn out.
I guess the 5k machine missed that part.
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Thu Sep 08, 2016 4:47 pm
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.
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Thu Sep 08, 2016 7:08 pm
by brian0918
...........
Re: Diagnosing expansion valve stuck open vs faulty compressor?
Posted: Thu Sep 08, 2016 10:05 pm
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.