With the AC running, what should be a the normal center vent outlet temperature at any given ambient air temperature? Is there a rule of thumb that says it should be 'X' degrees below ambient?

The above assumes that the AC has been running for at least 10 Min, and that it is R134 based.

Thanks

Phil

__________________
'95 E300 Diesel, 264,000 Miles. [Sold it]

You'll likely receive as many opinions on this as there are on the "what oil to use" subject.

I've seen 134 cars blow ice cold air and I mean ice cold. These 134 systems were in Asian cars.

For me, if you're not getting at least 45 degress F after it's cooled down, you're not going to stay cool long.

I have a 17 yr. old Accord running R-12 that blows 38 degree F in the low 90's. Not bad.

So somewhere between 40F - 45F would be ok in my book.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Here are a couple of graphs showing what the various temperature and pressure specs. are for a Porsche 993. I've never seen equivalent data for an MB, although it probably exists.

Attached Thumbnails

   

how do you test the temp? hold a thermometer in front of the vents?

I agree, 45 degrees F seems about average. If it gets MUCh colder than that you run the risk of the water freezing on the evaporator coil.
Use a thermometer resting right into the vent, most techs use a digital thermometer designed for this job, long probe so it can't fall into the vent.
Gilly

__________________
Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)

Nominally, you should see a 30-40 degree drop from ambient. But there are many, many variables. Humidity - dry air cools more than humid; the a/c system expends much of it's capacity dehumidifying moist air. (The old latent vs. sensible heat thing.) Compressor output, which is related to engine speed. Air flow over the condensor, related to vehicle speed (and in Texas, wind speed and direction ).

I agree with the previous posters - unless it settles in at 45 degrees or less, it won't be really comfortable. Fifty is tolerable, but much above that and it starts to have a clammy/humid feeling to the air.

- JimY