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Post by ChrisJ on Aug 9, 2013 19:39:35 GMT
Is vacuum pump oil acceptable for use when bleeding a CA machine of NCG? I don't have any refrigerant oil handy but I have a gallon of quality vacuum pump oil coming.
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Post by jhigdon2 on Aug 10, 2013 2:23:39 GMT
Yes should be fine. Your not really getting any significant amount in the system,and vac pump oil is mineral oil also.
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Post by cablehack on Aug 10, 2013 10:03:22 GMT
I've always used light sewing machine oil just because it was convenient and the nozzle on the bottle is just right for dispensing it drop by drop into the charge valve. I was about to use 4GS compressor oil via a syringe on the CA-1, but it still hasn't needed a purge. (I'm actually amazed at that).
Provided the high side is at a positive pressure, none gets sucked inside, and even if it did, it's going to be so diluted anyway.
How to know if the high side is positive? Run the fridge under load; eg. tray of hot water in the evaporator and the door open. This will make the condenser run warm; about 80F.
Incidentally, another extremely useful tool is a point and shoot infra red thermometer. This instrument will tell you immediately what the various temperatures are around the system. For example, if the float chamber is within about two degrees of the condenser temperature, then NCG's do not need purging.
And of course, you can see what the evaporator temp gets down to - a help in deciding if the needle and seat are worn.
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Post by ChrisJ on Aug 10, 2013 16:30:16 GMT
The issue I found with an IR thermometer, at least mind anyway is it depends on where you point it. As in if you point it at the raised parts of the evaporator it will show differently than a flat part.
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Post by cablehack on Aug 11, 2013 9:02:15 GMT
I noticed that too, but one could assume the colder of the two temperatures is the correct one. Alternatively, just point it to the bottom of the evaporator inside where it's all flat. That's where the manual shows the thermometer to be stuck.
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