Improved a/c by cleaning the radiator & condenser - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 07-24-2016, 08:07 PM

Recently the a/c condenser on my '95 E300D sprung a leak and I was faced with installing a replacement. To save a few bucks I decided to take a chance on one from the local Pick-n-Pull DIY auto scrapyard. I got lucky and found an apparently good one from a 1993 300E (6-cylinder, twin-fan cars all got the same condenser). A clue that the condenser was good was the hissing I heard as I disconnected the refrigerant lines. Apparently the yard guys didn't completely empty the system before putting the car out in the yard.

The surprise came when I removed the old condenser—I thought I had been keeping it so clean! With the aid of a pressure washer I cleaned the fins of both the radiator and the new condenser before re-installation. The second surprise came when I discovered the a/c worked better. This I could see, not in the temperatures achieved, which didn't change, but in the actions of the compressor and the aux fans. With clean fins the condenser worked for efficiently: the compressor now doesn't run as much to keep the interior cool and the aux fans don't run as often to keep the refrigerant pressure down. (Both of these I monitor in the cabin with a couple of LEDs.) The green LED illuminates whenever the a/c compressor's clutch is engaged by the Klima relay and the yellow LED whenever the pressure switch in the refrigerant line turns on the aux fans in low speed.

Without some other reason (like my leak) I can't recommend people disconnect their a/c plumbing—refrigerant is expensive. However, it should be possible to remove the cooling system's radiator, allowing it to be cleaned outside of the car and the condenser to be cleaned in-place. I recommend anyone whose car hasn't been touched in this area for many years to at least take a look, see how much is stuck in the fins.

Jeremy