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Discussion Starter #1
I've replaced all the components of my a/c system and am running R134a. I had my mechanic evac and fill last year and it ran fine. The car is stored for the winter.

Now I'd like to check the psi myself (I have the gauges), but don't know what the readings should be for R134a.

Does anyone know or can link to a table with the pressures? Thanks.
 

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I've replaced all the components of my a/c system and am running R134a. I had my mechanic evac and fill last year and it ran fine. The car is stored for the winter.

Now I'd like to check the psi myself (I have the gauges), but don't know what the readings should be for R134a.

Does anyone know or can link to a table with the pressures? Thanks.


Both B20 and B21 are the same. Fuel injected. Not sure about the carbeurated models.
 

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I've replaced all the components of my a/c system and am running R134a. I had my mechanic evac and fill last year and it ran fine. The car is stored for the winter.

Now I'd like to check the psi myself (I have the gauges), but don't know what the readings should be for R134a.

Does anyone know or can link to a table with the pressures? Thanks.
Although another member has already provided a chart, it does not have the R134a information you asked for, only the CFC-R12 pressure.

In a typical R134a (or retrofitted system) pressures usually reside around 140-200 on the high side and 30-50ish on the low side depending on system design and efficiency. It is common to still see sleight bubbles in the sight glass of a R134a retrofitted CFC-R12 system when properly charged, were as a CFC-R12 system properly charged with CFC-R12 should have no bubbles. This is due to the 70% charge requirement when retrofitting. So our systems which require 2lbs of CFC-R12 will only use 1.4lbs of R134a.
 

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I've replaced all the components of my a/c system and am running R134a. I had my mechanic evac and fill last year and it ran fine. The car is stored for the winter.

Now I'd like to check the psi myself (I have the gauges), but don't know what the readings should be for R134a.

Does anyone know or can link to a table with the pressures? Thanks.
Why are you testing the system? Does it work? If so I wouldn't mess with it.
 

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I was thinking the same. If it's cold it works. If it's not it needs to be refilled and checked.

Oops! I didn't even notice it said R-12. If that is the case, then OP needs to give more information about the vehicle. If it's converted, there may be a different condensor/dryer and even lines. This all changes how much refrigerant you will need and pressures as well.

If it was a basic conversion (just fittings and flush), you could probably could get away with less frigerant than required. Maybe 25-28ozs instead of 30-34ozs. The things that would be different are the pressures.

The only thing pressures would tell you is if you were either low on refrigerant, or if you had a leak or a block somewhere in the system. Best thing to do as a DIY is to get some dye and a UV light. But you really don't want to be playing with that stuff. It's really harmful to the atmosphere.
(But my straight pipe out the side isn't :evil smile:)
 

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Discussion Starter #7
Conversion included replacing lines, dryer, condenser and compressor.

It's cold (but I just don't think as cold as last year when I had it filled). But I did check the pressures and found about 50 on the low side and only 80 on the high side. This seemed odd to me.
 

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A/c

Low side should be around 45 and NEVER exceed 185, at 1500 RPM, on the high side or the over pressure valve, (if it has one) or the seal will blow.
Like the others said, "if it's not broke, don't fix it until it is".

Cheers
nigel
 
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