View Full Version : bypass valve lockout
09-06-2005, 03:17 PM
I have several evaporator coild that need to be removed and cleaned then put back. I am planning on doing a lock out on the liquid line and allow the suction to get down to about 20psi then do a lockout for the suction that way the refrigerant is in the condenser. if the bypass valve in the compressor opens due to excessive pressure, will it reset so that the compressor will work normally after I open the lockout valves. Just dont want the by-pass opening and then not closing back. Anyone had expreience with this before???. In the few that I have done, some of the by pass have opened and then shut when the system pressure is returned to normal. ANy surprieses or things to be weary of???
09-07-2005, 12:30 AM
They tend to do that when they are overcharged to begin with or on long line sets.
09-07-2005, 05:24 PM
...or non condensables.
09-07-2005, 05:50 PM
I call this a pump down and perform it often with heat pumps and a/c units. After evap is re-installed braze on a liquid drier and vacuum system before re-introducing the refrigerant.
09-07-2005, 11:03 PM
guys, thakx a lot for those that have tried to answer my question. But my main concern is that will the by pass vlave in the compressor close after the system when the liquid line pressure go down or have any of you had problems with the by pass valve staying open???. If the by pass valve stays open the copmressor will have to be replaced and that will be at my cost. I definately dont want to do that. So please advise
09-08-2005, 08:57 AM
Most often it does but there is no garuentee it will close. It is a last ditch safety intedned to prevent a much larger failure. I have had many close and work fine, I have also had a few that would not reset.
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