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First of all thanks for all the help. I monitored this site for months and gathered info before buying my car. It has a ways to go but it is what I have always wanted. I have a 69RS/SS that I am starting to rebuild. It has factory air. I am trying to get the A/C in order, since the car is at my uncle's shop 2 hours away. Has anyone converted their factory air over to Freeze 12 or R134A. I have been told taht you can and that you can't w/o buying some additional parts. I am buying a new POA valve and a new expansion valve, I am wondering if I should buy the POA update that Year One sells. Not even sure what it is. But in the same page it says taht the expansion valve won't work with R134. I need advice.
 

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I don't have my Year One with me, but I know that the POA valves you get now, are "replacements" which means they will function like the originals, but do not look line the originals.
 

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I've converted mine over and R134A works just fine. Maybe the air is a couple of degrees warmer than if I was running R12 but certainly within acceptable ranges. On 90+ degree days the air will blow out of the center vent at about 50F.

The POA valve is located on the outlet line of the evaporator and it maintains a specific pressure within the evaporator (35 PSI I think). It has a sensing line that runs down into the evaporator core that senses the pressure inside the core and limits the amount of refrigerant that can get back to the compressor.

The expansion valve meters the refrigerant into the evaporator. It drops the pressure of the liquid in the line from the dryer and causes the refrigerant to flash to a gas.

You don't have to replace either the expansion valve or POA valve unless they are defective. But the R134A works at a slightly different pressure than R12 which results in a less efficient system when you use an R12 POA valve. I suspect that if Year One sells a retrofit POA valve then they have recalibrated on to work with R134. It probably isn't visually correct. You do have to replace the dehydrator (dryer) with one used with R134A. You also need to flush out and replace the compressor oils, as the type of oil used in an R134 system is not compatible with the oil from an R12 system. Other than that you should also replace all of your O rings with the newer high temperature green O rings.

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Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11
My 69 L48 - 350/300HP Engine
 

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R134 has a smaller molecule than R12. Supposedly, you should upgrade the hoses so it won't leak (very slowly) through the hoses. Be sure to get out as much of the R12 oil as you can. Also, replace the drier, It will have moisture and R12 oil in it. I know, said already! There are aftermarket filters you can put in-line if you're worried about any junk floating around the system.
 
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