Our '94 124 (e420) blows cold sometimes, and others, not. It seems to work about every other time we get in and start-up the car. The facts:

- A/C always blows air
- Sometimes the air is hot (and never cools)
- Sometime the air is cool (and never warms)
- It works or does not, per trip. That is, we'll get in the car for the first trip of the day and does not work (blows warm). We park, shop (or whatever) and get back in and it works fine. It does not seem to improve or worrsen during a trip. The difference occurs when the car is parked, tuned off and sits (2 minutes or an hour).
- It mostly, but not always, does *not* work on the first trip of the day. That trip can be at anytime I work at home and my wife does not work.
- We live in Austin. We won't see the south-side of 70F (at 5am) until Sept or Oct....

If there were any pattern to it at all, I'd say it tends to be more likely to run when it was started when the engine was already warm (but not always...).

That's my story and I'm sticking to it...

__________________
Thanks,

Joey

'88 560SL Pearl Black/Java 152K
'94 E320 Anthracite/Grey 89K


Previously:
'94 E420 Black/Bamboo
'90 300E
'71 280SEL 4.5

Could be an issue with the heater valve.

Have you check to see if the compressor is engaging when the system doesn't cool?

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
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Have you recently change your belt that drives the compressor.

Last year when I changed mine. their was not enought tension and the compressor came on sometimes and did not come on at other times.

The fix was to tighen the tensioner.

Regards,

Tony

__________________
Tony

1993 300SL
2005 SLK350
1999 SLK230 (SOLD)