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System blowing cool and pressures are off.

bteddy on Fri May 04, 2012 9:20 AM User is offline

Year: 1997
Make: Plymouth
Model: Grand Voyager
Engine Size: 3.3L
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 45
Pressure High: 250
Country of Origin: United States

Hello,

I replaced a broken high side line.
Replace the accumulator.
Replaced oil.
Vacuumed system for 2hrs (was opened for a couple of months).
Let sit for an hour to see if the system would hold the vacuum.

Started charging system, at the 3/4 full point (36oz of 48oz) the gauges were reading the max for the system.
I ran the engine for an hour and the reading decreased to below max.
I added the last 12oz and the pressures went up to Low: 45psi (37psi max) and High: 250psi (210psi max).
I ran the engine for a couple of hours (drove around town) after and measured again, no change.

The system dual zone, front and rear, the front blows cool, not cold, intermittently and the engine overheated .
I could not tell what the rear was doing, couldn't run rear without running front.

Questions:
1)What is the procedure to test for a stuck expansion valve?
2)How do you determine if it is the front or rear expansion valve that is stuck?
3)How do you unstick an expansion valve?
4)My low side connection valve is near the line connection to the compressor and the high side is in-between the expansion
valve and the accumulator, what would I disconnect, and where would I hookup to back flush the system if it is contaminated?
5)There is not a sight glass on the system, is there a way to test for air/moisture in the system?

Thank you for any help you can provide.

mk378 on Fri May 04, 2012 9:45 AM User is offline

Engine overheated-- sounds like not enough airflow through the condenser / radiator. Are all fans working? Apply water to the condenser and see if the pressure comes down a lot.

American dual-air vans should have an OT on the front and a TXV on the rear. Turning off the rear fan should cause the rear TXV to close down completely, the pressure should drop due to reduced heat load.

Edited: Fri May 04, 2012 at 9:48 AM by mk378

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