190e Heater Trouble

[marcushill]

The heater in my December 1992 190e 1.8 blows only cold air and appears to have no circulation through the matrix. Having read other threads the next step should be to check / clean the duo valves. As I can't locate these in the engine bay my question is does a 190 have duo valves and if so where are they?
Thanks.

 

[grober]

You don't have the duo valves which are eletrically operated you will have a single vacuum diaphragm lever operated valve. Sometimes they develop leaks and stop operating. Its half hidden under the bonnet in the space under the windscreen. Its beneath the wiper motor assy on the offside next to the heater box. There is a vacuum pipe running to it that controls the flow.
Try tracing the small heater pipes that lead from the engine into the passenger compartment and you will find it. See the pic.part of the wiper mechanism is removed

 

[marcushill]

Many thanks Graeme. I replaced the diaphragm with a length of copper pipe so I suspect its the matrix that is blocked.

Marcus

 

[grober]

There is a vacuum operated diverter flap inside the heater that can also fail meaning no air flows thro the heater matrix. Best way to test if the matrix is blocked is to feel the supply and return pipes once the engine has heated up and the heater is switched on . Don't put on the fan which will accelerate heat loss from the matrix. If the return pipe is hot/warm then you are getting circulation. I believe people have back flushed a blocked heater matrix with a good degree of success in some cases

this is a good source of info http://s14.zetaboards.com/mercedes_190_club/index/

 

[Sp!ke]

I seem to have started suffering from lukewarm heating on my 190.

Anyone know where is the return hose from the heater matrix on the 2.0L model? The inlet pipe runs up along the top on the drivers side but I cant seem to spot the outlet pipe.

I also see a little vacuum operated thing up near the inlet pipe and the vacuum connector hose does have some cracks in it so I wondered if the vacuum opened or if it closed this inlet pipe.

This could be a two minute fix or a painful citric acid flush job depending on how this vacuum operated switch works.

 

[stwat]

I seem to have started suffering from lukewarm heating on my 190.

Anyone know where is the return hose from the heater matrix on the 2.0L model? The inlet pipe runs up along the top on the drivers side but I cant seem to spot the outlet pipe.

I also see a little vacuum operated thing up near the inlet pipe and the vacuum connector hose does have some cracks in it so I wondered if the vacuum opened or if it closed this inlet pipe.

This could be a two minute fix or a painful citric acid flush job depending on how this vacuum operated switch works.

Hi spike. The outlet comes out from the bulkhead on the other side of the engine next to the oil filter.

 

[Sp!ke]

yeah I sorted it today.

Interesting conversation at the chemist asking for Citric acid (drug dealer cutting favourite substance apparently) .

Flushed the system through a few times with water, contents of bucket looked like slurry.

Filled system up with water and citric acid mix and ran it for an hour before flushing through a few more times and then coolant.

Its so hot now that I dried up my eyeballs testing it. :bannana:

 

[stwat]

Glad you got it sorted.

The heaters can certainly get seriously hot!!! Do you find it warms up much quicker too? Mine is belting hot air out after only half a mile or so.

 

[219]

I well remember stripping out the dash on my 2.6 to replace the matrix which was leaking and would steam up the windscreen when I bought the car ( I think this was why it was for sale ) .

The job wasn't as horrific as I expected , easily done just by following the steps in the Haynes manual . It did take me most of the day from start to finish , but a roasting hot heater at the end .

New matrix was £70 odd from ECP .