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replace the evaporator and expansion valve..low side reading high

mktbully on Sun May 29, 2011 10:57 PM User is offline

Year: 1992
Make: Lexus
Model: SC400
Engine Size: 4.0
Refrigerant Type: R134a
Ambient Temp: 75
Pressure Low: 87
Pressure High: 100

Swapped out a leaking evaporator and expansion valve. i added about 1/2 to 1 ounce of oil back in the evaporator.
swapped out the drier.

pulled vac for 30-40 min. closed the valves and no leaks for a good hour.

hooked up a can of R134a and tipped the can and opened the high side and started off a little liquid in the system. then closed it and went to change the low side.

ac is on and car is running. i hear hissing behind the dash (evaporator?) and the compressor is moving but the air is not cooler (i'm sure b/c of the low amount of charge). the pressure reading is pretty much holding steady where they at. low side is not going down. should i continue to charge (add more R134a in)?

did i botch something up on the install?


HVACNY on Mon May 30, 2011 12:54 AM User is offline

What do your guages say after the first can?If theirs gas in the system after the first can the hissing your hearing is the system filling..If theirs no gas in the system after the first can u have a leak.

mktbully on Mon May 30, 2011 10:14 AM User is offline

low @ 87
high @ 100

thats after the first can. is the low supposed to be that high?

Dougflas on Mon May 30, 2011 10:30 AM User is offline

make sure the handwheels are closed. Is the compressor engaged?

mktbully on Mon May 30, 2011 11:27 AM User is offline

yes the compressor is engaged...that's when i hear the hissing. if i shut off the AC the compressor disengages and no hissing.

handwheels? can you explain what are handwheels?

iceman2555 on Mon May 30, 2011 5:39 PM User is offlineView users profile

The system is seriously undercharge. The hand wheels are the rotating devices on your gauges..the ones that open and close valves in the gauges. If the low side is not closed ..the indicated pressures are the source pressures...the can in your hand.....the hand wheels or ports must be closed to isolate the system from the charging cans. Get the system properly charged and then determine if a problem really exist.

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

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