Just added a can of 134 Freon to my '94 320E until all the bubbles were gone from the sight glass. The dashboard output temperature, max. cold setting, max. fan with an ambient of 75F is about 53 degrees. Is that about right for a 134 system?
Many thanks!

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'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet- under restoration
'86 560SL 124K Miles-Sold
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
07 SL550, 14K Miles

After there is time for pressures to equalize and car to cool off awhile it should be 38 degrees. If not, it is either low on refrigerant or the vacuum pod on the outside air door is bad allowing outside air to raise the vent temp.

When first starting up a properly operating climate control system in one of these cars it will drop the a/c intake air temp by about 30 degrees, so it takes awhile to keep circulating the air until it gets to the 38 degree point.

Do not add more refrigerant until you have a set of manifold gauges so you can monitor the high side pressure. Without monitoring high side pressure you stand a good chance of ruining something in the a/c system.

Good luck,

Many thanks for the good advice Larry. What should the proper operating pressures be, high and low side? I can borrow the gauges but I need to know what to look for.

__________________
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet- under restoration
'86 560SL 124K Miles-Sold
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
07 SL550, 14K Miles

The pressures will vary depending upon ambient temperature. The best investment you could make at this point would be the $15 for an automotive A/C manual. The best one I've seen is the one from www.ackits.com.

They will give you the procedure and the charts you need to check the charge properly.

Good luck,

In the model specific climate control manual, MB publishes graphs showing the expected high and low side pressure, based on ambient temperature and humidity. It also includes the expected discharge temperature of the cooled air.

It's impossible to give a blanket answer for high side pressure. It varies tremendously between an overcast 65 degree day and a blazing, humid 105 degree day. Somewhere between 150 & 300 are typical numbers. Not very useful without context, I'm afraid.

- JimY