My C280 is running hotter than normal...around 110-115 degrees. Temp goes down when the a/c is turned off or while running freely on the expresway. Fan clutch is new, and thermostat was eliminated. Aux fans runnig well. System is clean including the a/c condenser and radiator. Any suggestions? thanks

 

"Thermostat was eliminated".

I'm sure you're aware of the old argument that removing the thermostat can actually cause a
given vehicle to run hotter due to the water running through the radiator TOO quickly, and
therefore not having a chance to cool. BUT> if your car was running at the proper temp. before
with the thermostat out, then that's not it. If you JUST took it out, and it is doing this only since
you took it out, then I would put the correct one back in and at least try it. It's worth a try just
to see before you spend a lot of money on something expensive and that's not it, right? Just
trying to help here....not assuming you don't know about the thermostat removal legend.

 

I just had my C230 in for overheating and the a/c not working. It would cool down on open freeways too. Mine was the blower motor and had it changed out and now runs great again.

 

I thought we were talking about the ENGINE temp. here.......no?
Anyway, I was.

 

Discovered today that aux fans are NOT running at high speed when needed to cool down the system. Removed the relay that activates them in high speed and jumped terminals and fans run speedy. Relay is good...tested outside with metter. There is a harness connector besides the thermostat housing that if disconnected, and with the realy in place, fans run in high speed also . This connector has four wires and is also besides the temp. sensor sending unitto the panel guauge. But if disconnected then there is no current to the a/c compressor. Hope this helps in getting a better diagnosis. Thanks

Note: The guy indicating that his a/c was affected by the fans may be correct based on this harness that if disconnected, fans run fast but the a/c will not work.