Heater not blowing hot w219

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Csdrcallum

Member
Joined
Jun 6, 2020
Messages
38
Location
West sussex
Car
Cls 63 amg
First time since owning the car for a week I've turned the heater on.
Noticing no heat being produced until digital read is put to 'HOT' when moved back to 32° it goes cold again.

Suspecting the heater valve but unusual that it does produce heat once put in the hot position.

Any ideas?
 
Hi,
The fact it goes immediately cold when you take it 32 I would say it is the heater display control unit, thats where I would start before replacing the heater valve.
 
Well I hope you sort the problem out,but that is two members on here in two days who have not checked everything when buying a car,I know the buzz from sitting in it and starting the car,but one guy did not check the windscreen washers and wipers,and you the heater blower,ok both of you can take the car back and get it sorted,but the other guy had a two hour drive to get back to the garage,push all the buttons and if you do not know what they do ask.
 
Well I hope you sort the problem out,but that is two members on here in two days who have not checked everything when buying a car,I know the buzz from sitting in it and starting the car,but one guy did not check the windscreen washers and wipers,and you the heater blower,ok both of you can take the car back and get it sorted,but the other guy had a two hour drive to get back to the garage,push all the buttons and if you do not know what they do ask.
Cheers. I did check the heating/air con worked but must have put it on max and minimum. Also checked the demist but it was a scorching day so didnt want to put heating on for too long.
 
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Hi,
The fact it goes immediately cold when you take it 32 I would say it is the heater display control unit, thats where I would start before replacing the heater valve.
Any suggestions on how I can check the display?
 
Assuming you bought from a dealer of some sort , take the car back and point out the fault .

let them do the diagnosis
 
Hi,
Having re-read your first post again, does this behavior happen on all 4 heater zones?, if it does then I agree with you're diagnosis of a faulty heater valve, but if it is isolated to a specific zone or left or right temp control then IMO it will be heater display control unit.
Second hand control units can be bought for less than £100 on E-Bay, or you might be able to get you're one repaired.
 
Hi,
Having re-read your first post again, does this behavior happen on all 4 heater zones?, if it does then I agree with you're diagnosis of a faulty heater valve, but if it is isolated to a specific zone or left or right temp control then IMO it will be heater display control unit.
Second hand control units can be bought for less than £100 on E-Bay, or you might be able to get you're one repaired.
It happens on all 4 zones. Both front and rear blow cold until placed on 'HI' settings.
 
Unless it was a private sale , you should take the car back to the dealer/trader you bought it from since so soon after the purchase , they are obligated to rectify such faults . You shouldn't have to waste your time and money on this .
 
Unless it was a private sale , you should take the car back to the dealer/trader you bought it from since so soon after the purchase , they are obligated to rectify such faults . You shouldn't have to waste your time and money on this .
I've contacted the dealer who has asked if I can get it diagnosed before he the repair is carried out
 
Should the diagnosis not also be the responsibility of the dealer?
He will I assume be covering the cost of diagnosing. It's just that his dealership is over 1 hours drive from me so more convenient for me to get it checked out local.
 
I would just get the duo valve replaced, it's a cheap part. It should be listed as a common failure part for 4 zone climate control optioned cars (W211/W219).

The duo valve controls the airflow temperature for each zone.
 
He will I assume be covering the cost of diagnosing. It's just that his dealership is over 1 hours drive from me so more convenient for me to get it checked out local.
You are within your rights to ask him to collect the car from you , leave a courtesy vehicle, and bring yours back fixed .
 

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