R134a system pressures

[lsupcar]

My system has been converted to r134 for many years. Now it is not blowing as cold as it used to. I have the manual and the temp/pressure graph for r12, but wondered if the pressures were different for r134.
I have a manifold gauge to use but want to accurately use the readings.
Thanks.
Bill Z

[Dave @nz]

Hi Bill
On my gauges- Low side 15-20 psi on a normal warm day while holding the revs at around 1500, you should see the gas bubbles clear out and disappear in the receiver dryer sign glass. On a hot day I sometimes have a garden hose available to spray the condenser to cool it down to see if the sight glass clear out and the low pressures come down to 15-20 psi.

I dont know what the high side runs at I do everything through the low side.
Dave.

[lsupcar]

Well at 2000rpm I was getting at most 34 psi low side, 225 psi high side with center vent at 64 F*. This at 90* ambient.
To my thinking, normal low and low high side equals bad compressor.
I do not know if they are NLA but will look into it
it is cool enough at present so won’t do anything soon.
Thanks

[mtony]

Well at 2000rpm I was getting at most 34 psi low side, 225 psi high side with center vent at 64 F*. This at 90* ambient.
To my thinking, normal low and low high side equals bad compressor.
I do not know if they are NLA but will look into it
it is cool enough at present so won’t do anything soon.
Thanks

This post helped me a lot when i was working on my A/C:

http://www.bimmerforums.com/forum/sh...roubleshooting

[M3 Frank]

Search for: Nominal Air Conditioning System Pressures R-12/R-134a technical article from BMW.

B 64 13 92 (3646) Woodcliff Lake, NJ
Product Engineering
October 1992

This site will not allow a .pdf upload.

[lsupcar]

Thanks everyone.
Couldn't find the BMW technical article though.