Heating Problem Once Again on W124

[rumelk]

Hey Peeps,

This time last year i was baking in my 124 with it's new matrix, and was awesome. However for some reason now it's quite the opposite. I have no heat what so ever!!

Background:

Last December, after eventually diagnosing my heating problem, which happen to be a old and blocked matrix, i changed the duo valve, control panel and the heater matrix, which had fixed the problem. FYI i dont have A/C.

Problem:

NO Heating! LOL

I've checked the input pipes from the duo valve which shows the water going in and the matrix return pipes which has hot water, so clearly the matrix is doing it's job, but the heat isn't getting into the cabin. I've advised that it may be the flaps which have not opened up hence the heat isn't getting into the car, but the dials are spining and you can hear it open and closing the flaps.

Is the flaps situation true? also are there any thermostats or sensors in the bulkhead that i should look to change/investiage?

Any help would greatly be appreciated

 

[grober]

IS THE circulation FAN RUNNING? The duo valves are on the discharge side from the heater with usually a single common feed line from the cylinder head. There is also a supplementary electric circulation pump- on some models its part of the duo valve assembly -on others its hidden under the washer bottle airfilter box----- worth checking its operation. There is a cabin air temp sensor which is located in the light assembly above the windscreen. There's a little fan which draws cabin air in thro a sensor up there some times they go down but usually the fan goes noisy first.

 

[rumelk]

The Circulation fan is running, as when i put the fan to 4 your can feel the cold air coming out. The Duo Valve does not have a single feed from the cylinder head (in my vehicle), it has a single feed into from the xpansion tank, going into the electric circulation pump (as you stated, which is working as ive checked the water pressure after the duo valve) which goes into the duo valve, from the duo valves two pipes go into the matrix and one exit pipe which returns back into the bulkhead (by the battery)

 

[grober]

Other possibility is that some of the vacuum actuators to the various heater flaps have failed or you have a vacuum leak somewhere. I think there is a manifold at the side of the heater assembly with leads to the various actuators- these can be tested using a Mitivac type vacuum tester. Mityvac

 

[rumelk]

will that a go, if it has failed, what's the remedy?

Many Thanks