Heater

[JUSTJEFF]

BUMP! My 190 is giving out only warm air NOT hot air even on max. I checked the valve mentioned above. I took off the red vacume line which runs through the bulkhead into the car and I pushed the arm on the valve upwards then put my finger over the vac inlet and it stayed up. The default postion seems to be down (ie about horizontal). Can anyone tell me if the valve working okay or is it dead? Also should the valve "leg" move up/down when the heater controls are turned from cold to hot?



Mike.
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1990 190e 2.0 ltr (2003-2006)

I found this old thread from 2003 that was not answered...... Any one know the answer about the "leg move" on the heater valve as i have the same problem as Mike with the heater blowing out luke warm air only

 

[wireman]

I had similar problems and replaced the valve, I dont have the old one to hand but it is actuated by vacuum to close off the water in the cold position of the dashboard control. It is only a simple gate valve and I replaced mine because of a very slight coolant leak and a very lukewarm heater. It stopped the leak but did not restore the heat, checks were attempted to determine that the matrix was not blocked, You can get a condition where most of the tubes in the matrix are blocked but there is a sufficient number of clear tubes to carry water through them making it impossible to determine the condition of the matrix with only a simple flow check.
Further investigation would entail removal of the matrix, a daunting task which I chose to avoid by getting shut of the car (rust and the MOT were the real reasons for my parting with it), it was only too cold during Jan-Mar for the rest of the year it was OK.
You may try flushing the cooling system with one of the propriatory chemical agents (Radflush etc) and replace the thermostat, if this works you have won but I have some doubts that the matrix (if it has blocked tubes) will be cleared by this method since the flow will be through the clear tubes bypassing the choked tubes and the cleaning stuff will not be able to get in to where its needed because it will flow through the clear tubes.
To replace the matrix you have to remove the dashboard and centre console, then the heater air handling unit behind which is the matrix, simple realy should be done in a day or two.
Good luck

 

[mercman149]

Same problem

My 1989 190E recently started doing the same thing. I replaced the heater valve due to a fluid leak, and although this made it blow marginally warmer air, it is still alot colder than it should be. Strangely, the air blowing to the screen with the control directing air that way, does blow hotter than to anywhere else. Could the flaps which control air flow direction be at fault, mixing too much cold air with the hot?
I am going to try flushing the system to see if that makes a difference later this week. Thank goodness the weather has been so mild, but it will not last and I need to get the cause established and fixed (if possible).