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View Full Version : How to diagnose LLSV?


cretan
11-21-2008, 03:45 PM
What is the best way to diagnose a leaking solenoid valve.Keep in mind some compressors don't have a rotolock to isolate the compressor.
zzonko
11-21-2008, 04:16 PM
If your talking about the valve being partially washed out and refrigerant going by the valve in the closed position, wouldnt there be a pressure drop and a colder line downstream? frosting? hissing?
jpsmith1cm
11-21-2008, 04:30 PM
If your talking about the valve being partially washed out and refrigerant going by the valve in the closed position, wouldnt there be a pressure drop and a colder line downstream? frosting? hissing?

Not always frost, but it will be colder. Of course, it will be colder when it closes correctly, too, so don't rush.

Honestly, when I suspect a LLSV, I tear it apart and look. Anything looks funny and I rebuild or replace it.
gerryboy00
11-21-2008, 05:15 PM
disconect the LLS and keep the suction pressure low by starting the compressor manually....check for frost after the valve
tjc76
11-21-2008, 05:23 PM
cretan- it sounds to me from reading your original post that you want to isolate the compressor from the system, correct? the way i interpreted your post was that you have a pumpdown system which either doesn't pump down, or recycles pumpdown frequently when off, correct? are you thinking that you may have leaking valves in this compressor? give us a little more info with what you are working on or exactly what your line of questioning is.
A1 Burt
11-21-2008, 10:31 PM
measure temperature before valve & after valve
if you don't have suction valve then install a piercing valve near compressor
now front seat king valve pump system down see what is happen with system
and you will see what needs to be done
cretan
11-21-2008, 11:30 PM
All great replies,thanks.I am not working on a system now,just wanted to get some of the ideas out there.Thanks again!!
Phase Loss
11-22-2008, 02:02 AM
i check the TEV too at times. If the liquid line solenoid is closed and my TEV keeps feeding i know i have a problem.

now i know right as the solenoid closes it has to pump out, and it will feed for a little bit...but after a few minutes, if that TEV is still cold and feeding. you gota know something is fishy.
frigeguy
11-22-2008, 08:27 AM
Disconect power at the solinoid coil, watch the system? Some systems will pump down again depending on coil temp and pressure control settings, this being normal. Seen a few old ones work perfect 9 times out of 10, but now and then stick partically open due to wear on the brass (grooved) causing the disk to hang up. Rebuilding will seem to cure this but is not the solution! You will end up replacing it.