W124: A/C gets tired and engine gets hot. - Page 2 - PeachParts Mercedes-Benz Forum

juribe2 · #1 07-23-2009, 07:55 PM

Hi guys,

I have a 1995 E320 sedan (W124 / M104) with 95,000 km. It is the German version with a 5 speed automatic transmission, no cruise control and no automatic climate control (manual A/C controls).

Recently the car is showing some symptoms and I don’t know if those are related. Let me explain:

Air Conditioning: works fine almost all the time but after driving for 3 to 4 hours continuously, the A/C gets like tired and stops cooling. I can feel and hear the blower working but all I get is a soft warm breeze. If I turn the A/C off for 15 minutes and turn it back on, it works great again for some hours. I must confess I have never replaced the cabin filters (I will soon, I promise) but I don’t think that’s the problem.

Cooling system. In the last 2 years I have replaced: water pump, radiator, thermostat, pressure cap, expansion tank, serpentine belt and every hose in the system. I guess I could say, the car has a brand new cooling system. The car drives cool almost all the time (85 to 90C) on flat terrain, but when driving up a hill with some load or on slow trafic, it gets really hot (110 to 115). Both auxiliary fans are working (with the A/C and when temp is about 100 to 110) and get the temp back to about 90-95C but it stays in 110 if you keep driving up a long hill. I checked the fan clutch and is in good shape. The main fan spins free if I turn the engine on and off when cool and stops almost immediately if I do the same with the engine hot. I know the aux fans are there for a reason but the motor temperature used to be a lot more stable a couple of months ago.

Codes: I keep getting some codes on Pin 8: Code 40, Transmission overload protection switch… and, Code 41, CAN communication from engine control module faulty. Code 40 shows up from time to time but code 41 is always there when I read codes. I don’t know what this means but the car drives really good all the time.

This are a lot of questions and I really appreciate your patience and time. I’m sure I can save a lot of time and money asking to this forum, so thanks in advance for your inputs.

Do you think A/C and engine temperature troubles are related? I read once that some pressure thing in the A/C system has something to do with aux fans or something. I’ve been searching and reading but I haven’t found the solution to my problems.

Thanks again,

Juan