Gary Dodson
New Member
- Joined
- Jan 18, 2018
- Messages
- 5
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- Your Mercedes
- E220 cdi 2007 2.1
My heater blows hot on low speed but cold on high speed or auto??
Yes it gets to the correct temp. Also the heater does blow hot but only when heater fan is slow.Does the engine get to a proper temperature?
The car does get to the correct driving temp. I’ve replaced the heater Moyer as The old one squeaks and I changed the heater regulator.as above , need more info on this one pal
It didn’t work properly before I changed the heater regulator. I think the problem started in November when I replaced the water pumpDid it work properly before you changed those parts?
Thank you I’ll get my garage to do that as I don’t want to make it worseOk sounds like you have restricted water flow. If the heat goes slowly from hot to cold this is another indicator.
You could have an air lock in the heater matrix, a kinked pipe, a partially blocked matrix or failing duovalves (if yours has them).
Start with the cheap easy things first - try reverse flushing the heater matrix and bleeding the air out of the heater matrix. The way I bleed the heater is to get some temperature (pressure) into the cooling system, then loosen the connection to the heater matrix where it comes out the firewall (usually duovalve if fitted) then very carefully slide a thin screwdriver down between the hose and the pipe to allow the air to bleed out. Be very careful as you are dealing with hot water under pressure!!!
Most cars don't require bleeding but for some reason I've had a few that do.