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Old 08-25-2011, 10:37 PM   #16
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Quote:
Originally Posted by beenthere View Post
oil can break down. And does at times, and will clog the filter. A restricted suction filter drier drops system capacity, and causes the compressor to run hot.
*** Which causes the oil to break down faster, right? Setting up a spiral
of increasing heat and breaking down oil. Seems to me that when the system gets to that point you're screwed, filter or no filter.

- Jerryk

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Old 08-26-2011, 04:15 AM   #17
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Quote:
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*** Which causes the oil to break down faster, right? Setting up a spiral
of increasing heat and breaking down oil. Seems to me that when the system gets to that point you're screwed, filter or no filter.

- Jerryk
Without a vapor filter, you don't get the cascade effect(compressor doesn't run hotter and hotter). So you get a much longer life from the compressor.
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Old 08-26-2011, 07:49 AM   #18
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Without a vapor filter, you don't get the cascade effect(compressor doesn't run hotter and hotter). So you get a much longer life from the compressor.

*** OK,

That complicates things for me a little. I can't clear the system by blowing the bejezus out of it because of the TXV. So there will be crud in the system from being open for a few months.

So I really do nead that vapor filter. Which means I'll need to take the system down again, recover the refrigerant, remove the filter and braze in a stub. Not THAT big a deal. Except now I'll need to obtain a recovery unit.

I read about a trick where you close the system at the liquid output, then run it - and the compressor pumps all the refrigerant into the condenser, where it just builds up. Then you close the vapor input and just evacuate the rest of the system. I see two problems with this:
1: The compressor won't evacuate the system to an EPA-acceptable level.
2: When the input runs out of refrigerant, the compressor motor will burn up, because it depends on the refrigerant for cooling.

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- JerryK
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Old 08-26-2011, 03:46 PM   #19
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Its known as pumping the system down to itself. Scroll's are not suppose to be ran in a vacuum, so you can't pump all of the refrigerant back to the condenser.

However, its easy to pump the system back to itself and leave 5 to 10 PSIG in the lines and evap coil. Then connect a recovery cylinder that is under a deep vacuum to the lines and let then recovery cylinder pull out the rest of the gas, and bring it into a vacuum.
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Old 08-26-2011, 05:58 PM   #20
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... And then to refill the system after work is done....
I would vacuum the lines and evaporator - then open the recovery bottle and get my 5-10PSIG back. Then close the recovery bottle and reopen the condenser.

Is that about right?

- JerryK

p.s. Looking at the 30pound recovery cylinders on Ebay, they all seem to have an extra Schrader port to the side. Anybody know what that's for?
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Old 08-26-2011, 07:20 PM   #21
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You may be referring to the float connector.

Yes, you would just let teh vacuum of the line set and coil draw it back out of the cylinder.

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