Meanz

Hi Forum.
I have a 1997 c180 w202 and my car heater isn't working. I cleaned the duo valves and still nothing. I found out my circulation pump wasn't working, i fixed the pump and now the pump works 100% but still no hot air is coming out only cold. Anyone have suggestions???

optimusprime m1

Have you had the car long ? Did the heater ever work?

Meanz

yes the heater used to work a while ago then it stopped working,and I didn't know why. I just recently discovered that my circulation pump wasn't working and I just fixed it today..but still no hot air

optimusprime m1

hi what i have found is ,you must check the small pipe [nylon tube] that runns across the fire wall and down by the oil filter and it then pushes in to ablack rubber tube that fives in to the innlet manifold .It gets knocked off after oil changes . This is what takes vacuum to the heater box to operate the flaps. Look in there for any pipe thats not connected up .I do think its a vacuum problem.. Go on to Google search to find lots of answers like i did for you.

Meanz

thanks for the reply...I have checked the pipe and found everything is connected. I just noticed that the hose coming out of the circulation pump is not hot, which might mean the impeller isn't spinning, I'll take it apart now and have a look.

Meanz

Update!
I found the impeller is spinning but only a very small amount of water is going through... Not sure why

optimusprime m1

Have you connected it up right ,they can run in the other direction as well ,so then it wont get hot past the auxhiliary pump.Was the connection there for you to connect up to or have you connected it .. If i am right the punp takes power from the dash board switch.Or it might be that the duo valve is shut ,so no water will circulate ..Looking like duo valve problem to me

optimusprime m1

Did you clean it as per youtube video . The check you do to see if its working right is -When engine running remove the connectors from the duovalve you should hear them click . No click - not working .

ptcruiser

Also, it could be an air lock in the system restricting the water flow?

Meanz

It's strange though, every time I turn off the heater the water rushes through the pump, however when I turn it on it only trinkels through... I'm guessing I might need a new pump?

ptcruiser

Again, the airlock could be in the heater core.
You may need to disconnect the heater hoses from the core, and see what water drains out.
Normally, if you leave the return hose loose after, and refill the rad with the heater on, the water should start to flow freely out of the return hose. When that happens, clamp the hose tight and leave the rad cap off until you see the water circulating and no air bubbles. The car will need to be operating temperature so the thermostat is open and your getting full circulation.

optimusprime m1

,not the pump did you remove the conection on the duo valve as i asked ,to see if you can hear it click form it .One step at a time .Check duo valve clicking first.

optimusprime m1

The water wont flow through to the auxhiliary water punp if the duo valve is shut off.

Meanz

Sorry for the late reply. Duovalve is working, but like I posted previously, there is very little water coming out of the auxiliary water pump. If I leave it on for around 15 20 min it starts to get warm but no where near as warm as it used to get. However it is better then nothing.I might need a new pump. Thanks all for the helpful advice

optimusprime m1

What did you do to the pump to get it working ?

Meanz

Replaced the brushes

af1981

I have a suggestion sell it in south Florida no one cares for heaters here good luck mate