I have a 1994 C280 and I will routinely get hot air from side dash air vents while getting cold air from center dash vents.

I had the codes pulled when some other repairs where being done and got #49 auxillary coolant pump bad.

Other codes are 28, 50, 62, 60, 80, 82, 100. The shop who pulled these codes acted like these where not important codes. Can you tell me what these codes mean?

I have been told to replace the auxillary water pump and that there is a switchover block temp flap intermittent failure. I was offered no solution to the switchover block temp flap problem.

I have found the auxillary water pump under the hood (and can easily replace that) and have read that its function is to maintain uniform heater core temperature.

Doesn't the switchover block work from a vaccum source.

How do I fix this?

Common vac source problems occur at the motor source block.

I can't say what the codes are at home , but I agree to ignore them including the one about the aux water valve. Your problem is too much heat. The pumps do short and as a short might take down the controllers abilities (protection) to control the heater valve. If this is the case just disconnecting it should stop that problem (it will still set a code).

The problem with hot and cold should be in the heater valve or its control.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician