300TE A/C Question
 

I recently bought a 1989 300TE for my teen daughter. The car is in A-1 shape. I do have a question regarding the operation of the A/C which maybe other 300E or 300TE can help me with. (The info is not covered by the Owner's Manual)

When the system is set to the EC or A/C settings I do not get air coming from the center dash vents until one of two things happens:

1. The outside tenperature is above a certain point (usually over 65 degrees), or

2. I set the temperature wheel to its minimum (coldest) setting.

I do not get air from the center vents until after either 1 or 2, happen.

Otherwise the A/C and the heater work very well.

The A/C in my 1991 420SEL works differently. I can get air out of the center vents under almost any setting (except heater mode).

Thanks for your help :)

The way you explain it I see very little difference between the way each car is performing and that is as it should be.

The center ducts are not used for the heater function. You may see a different switching point from car to car, but your decription shows that this is happening.

I guess that's what I was trying to get at...
 

...does everyone with a 300E have a similar experience? The set point in the 420SEL seems to be different than the 300TE and I was wondering if this normal?

Otherwise the /AC-heater system works extremely well.

I have an '89 TE, and the center vents only open to a maximum of one-third, no matter what the setting or temp. Otherwise, the system is fine. Makes it difficult to keep a cool car, with constant mid-'90's outside.

Just my two cents....

CE Center Vents
 

I have A/C comming out of my center vents pretty forcefully in the Min position and anywhere in the cold range. If this is incorrect, I'm not complaining. On High Fan, it's enough to blow your hair back :).

I do have to admit that over 90 degrees or so, I'm not thrilled at the air cond when at a stop. While driving, it's at 40 degrees or so but when stopped it rises quite a bit. I just had it flushed, charged and checked and have talked to other 124 owners that say theirs are similar. I've alo talked to 124 owners that say they get theirs to "snow" inside. I wish I could get a little cooler tem at idle out of it.

Sorry to drift off topic. I had to "Vent".

When I test cars after repairs (very special job on a hot summer afternoon), I drive them down a divided four lane for 3 miles at 50mph in high blow condition. This is enough time for the system to stabilize and I get to see how low can it go. I expect to see at least 40 degree off ambient temp to consider it "good" A/C.

Many 300Es (especially pre 90 models) that will meet this criteria will loose ten degrees off this measurement when I sit at the light at the end of the three miles. Many early 300Es with 134 conversions only make 30-35 degrees off ambient in this test (remember high blow).

Steve, you sound "Right On"
 

Steve,

You sound "right on" with the description of the earlier cars. I get 40 degree vent temps on a 90 degree day which is fantastic but drop to about 52 or even 55 degrees at idle which is a bit annoying.

What was involved in the R-134 Conversion on the Benz? Standard o-ring, receiver drier and small part conversion or are there other things involved? I'm not too familiar with the MB.

I've done a few with good results but none match the cooling of the R-12 systems before. The 300CE is still R-12 but with the small condenser, I never even considered a 134 conversion for fear of worse cooling.

I did try an alternative refrigerant (ES-12a) with really good results almost identical to the R-12. 40 degree vent temps on a 90 degree day but almost 60 at idle which does not cut it.

Thanks for the info.

I added refrigerant 409 to my system the other day and it is working great so far. My friend who is a refrigeration guy did the same to his without changing seal etc.... after 4 years he hasn't added anymore and says it is still working great!