ptkacik

Does anybody have the recommended freon pressure ranges for the 2005 E320? I’ve search several forums and my MB troubleshooting DVD to no avail.

Or maybe it just the same as for any other MB or any other brand of car.

I’m guessing it will look like a table with columns of Ambient temp, low pressure range, high pressure range, and maybe something else.
Rows will be ambient temps etc.

Thank you,
Peter

Heguli

With the R-134a refridgerant, make or model doesn't matter, pressures are the same.

amosfella

https://realcold.co.nz/media/15239/pt_chart.pdf

ptkacik

Interesting chart but it doesn’t say what the high and low pressures are, just a static pressure. My concern is that there is some sort of affect of the MB expansion valve on the high and low pressures.

Mine are 32psi low and 178psi high at 80F.

Peter

amosfella

Static pressure is the easiest and most precise to measure that you have the correct amount of refrigerant in the system. With the car having rested for a few hours, put your gauges on, make sure the pressures have equalized, and measure the temp at ambient under the hood.

Dynamic pressures have a range. They are less precise. No, there's not that much difference in the expansion valve, or the system won't work. It's simple gas dynamics.

Here's a high low pressure chart.

https://www.acprocold.com/faq/r-134a...ressure-chart/

robbieas

I seem to recall reading something in this forum about needing to run the engine at ~2k RPM and taking the reading while at that RPM. I don't know the details and it might be BS, but I know I read it in here somewhere.