A/C Freeze-up

[wbrian63]

'92 300SE.
Took the car on its first long road trip last weekend. About 1,000 miles between Thursday AM and Sunday PM.

Car ran flawlessly, with the exception of the A/C. I recently had it evacuated and recharged at my local MB indie, the system was slightly low on freon.

I'm having trouble with the system freezing up. On the outbound journey, at about 2 hours into the trip, there was virtually no airflow from the vents. Setting the fan to high speed only resulted in lots of blower noise. Choosing Auto, floor, middle, upper, defrost made no difference, although we could hear the vent dampers cycling as the settings were changed.

Cut the system off for a while and when restarted, nice airflow and cold air. When we arrived at our destination and stopped for about 2 hours, there was a HUGE puddle of condensate water under the car - far more than I would have ever expected. I think this confirms the freeze-up situation.

I'm planning on taking the car back to the indie for more work to get this sorted out. I'd like to be armed with as much info as I can get.

Prior experience with A/C units that freeze up have always pointed to low freon level. I'm going to assume that's not the case with this unit since I'd had it filled less than 2 weeks ago.

NO - I don't know whether the evap has been changed. Obviously, the first check will be to see if the system is low again, and if low, a leak test to see where the loss is. I'm not initially inclined to believe its the evaporator - the car sat for almost 2 years and the A/C was only slightly low at that point. I've put almost 10K on the car since July and the A/C has always blown cold, but at moderate outdoor temps was prone to freezeup, and I could see bubbles in the dryer sight glass, which is why I sent it in for service.

Any suggestions would be appreciated.