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A Fustratingly Simple Question

Coltonis on Mon February 02, 2009 10:12 PM User is offline

First let me just say thank you to the entire forum as I can not put into words how much the information on here has helped me in picking out parts that I need to get a working A/C. I currently have a truck and two cars that I'm going to be outfitting and wouldn't have been able to do it without the wealth of knowledge posted here.


I first started to wonder about this when I was reading up about POA valves on here, but I googled/searched/scoured to no avail for an answer.
It appears every POA valve (POA Eliminator kits included) that I can find a picture of has an inlet, outlet, service port, equalizer port, AND an Oil return line. I have gathered that this Oil bleed line is necessary when a POA valve is used to allow the Oil to flow freely back to the Compressor. (Please feel free to elaborate and correct as needed)

My frustratingly simple question: Where in the name of Jesus H. Christ, does the other end of that Oil line get connected?

bohica2xo on Tue February 03, 2009 2:28 AM User is offline

Systems originally equipped with a POA valve have an oil bleed line from a low point on the evaporator back up to the valve itself. There is a low cracking pressure check valve in the POA body right where that line attaches. It looks like a normal schrader valve... but it is not. Do not replace it with a service valve schrader.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Coltonis on Tue February 03, 2009 5:32 PM User is offline


That makes sense now... so as refrigerant turns to gas in evap, oil seperates out and pools at the lowest point, the slightly higher pressure in the evap created by the POA valve would push the oil to the lower pressure suction line and back to the compressor...(right?)

Another loosely related question I have been pondering is, how necessary is a POA valve?

i understand its main function is to prevent iceing the evap. The TXV should limit the refrigerant somewhat to begin with, but I read mention that its not always safe to bet on the TXV for this purpose though.

(I realise this is touched-on quite a bit in other threads from a Cycling vs non-cycling systems performance , but for my purposes - here in AZ - would it still be a bad idea to leave off some sort of icing protection?)

Edited: Tue February 03, 2009 at 5:39 PM by Coltonis

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