Heaters

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MercMania

Active Member
Joined
Jul 14, 2008
Messages
346
Hi all I need some advice, I was driving my car other as normal all of a sudden the heaters/blowers came on themselves, when I turned engine off they where still running I left it thought might go off later so after couple of hours went back to the car in had trained the battery so jump started and the blowers still going so took fuse out few days later put the fuse back in and soon as I did blowers come back on took fuse out again.

Can anyone help and tell me what could me the problem?
 
Doesn't sound like a HEVAC ecu operation fault as they are still running when powered off and on again. Somehow the fan is getting a continuous live feed and it's before the fuse. So you'll need to check a wiring diagram and see what feeds it. Normally these are directly fed from the ECU and this may have a hardware fault. Others use a relay, and you may have a relay sticking open. Hopefully the latter as that's easy to fix. If the former you may need new ecu/repair.

Just an FYI, above is based on general knowledge, not specific experience of your Merc and it's HEVAC system, so take it in that context.

cheers, Steve
 
Ok thanx forgot to mention earlier it's a w202 model c class year 2000.
 
There is a relay unit behind front wheel arch liner, passenger side, worth removing and opening up, no idea what its like inside.
Maybe you could take a picture of the internals if you decide to investigate further.

Dec
832074d1394630908-c280-1994-auxiliary-fan-stage-2-rad-fan-relay.jpg
 
Thanx for images could be useful would u know if the radiator cooling fan relay has water in it?
 
Thanx for images could be useful would u know if the radiator cooling fan relay has water in it?

Yours might have - but I don't think it should have.....

That might be the problem:dk:
 
If it has resistors inside to control fan speed, then heat sinks are a pretty good idea.
 
Passenger side carpet is wet was thinking it could had come from the radiator cooling fan relay I that has water in it
 
I think there is some confusion here and we are barking up the wrong tree, I was talking about the radiator fan and you are talking about the heater blower fan inside the cabin, is that correct? If so the relay mentioned above has nothing to do with the fault.

If the passenger side carpet is wet then this would point to block drains and would explain the fault as the heater blower motor would have gotten wet.

Dec
[YOUTUBE HD]C_LeuzB36dQ[/YOUTUBE HD]
 
My CLK had water on the drivers side, it was blocked drains on the plastic shield under the wipers. Small hose and air compressor did the trick.
 
I think there is some confusion here and we are barking up the wrong tree, I was talking about the radiator fan and you are talking about the heater blower fan inside the cabin, is that correct? If so the relay mentioned above has nothing to do with the fault.

If the passenger side carpet is wet then this would point to block drains and would explain the fault as the heater blower motor would have gotten wet.

Dec
[YOUTUBE HD]C_LeuzB36dQ[/YOUTUBE HD]

It started with the situation with the heaters, which I mention in my first thread then when someone mention about the radian cover I thought that could be a reason y my passenger side is wet but my main concern is about the heaters
 
Anyone know where the heater relay is or what it look like?
 
I don’t think there is a heater blower relay, as the carpet was wet, maybe the blower motor got wet and blew the fuse.

Dec
 
Hi quick question for u all I can't remember how the controls work on my heaters, where I have the numbers in between there's dots and a dot before number 1 are the blowers supposed to kick in when i put it ok the dot before the number 1 or are they supposed to kick in on number 1?
 
1 is the first fan speed.

0 = the blower motor fan is off, almost no air comes into cabin when the car is moving forward.
The dot = the blower motor fan is off but air is forced into the cabin if the car is moving forward at speed

The fan symbol is not a speed.

1 = fan blows air into cabin, this is the first and lowest fan speed.
1 ½ = higher speed.
2 = next higher speed.
2 ½ = next higher speed.
3 = next higher speed.
3 ½ = next higher speed.
4 = next higher speed.
4 ½ = next higher speed.
5 = this is highest fan speed.
5329112466_d7bf9aa243.jpg


The fan has 9 speeds.
Picture source… http://www.mbclub.co.uk/forums/interior/102041-what-going-my-w202-heating.html

Dec
 
Does the ex light need to be on when heating is on as am not sure
 
How about the dot after the zero should it work on that or not

Read and all will be revealed.


1 is the first fan speed.

0 = the blower motor fan is off, almost no air comes into cabin when the car is moving forward.
The dot = the blower motor fan is off but air is forced into the cabin if the car is moving forward at speed

The fan symbol is not a speed.

1 = fan blows air into cabin, this is the first and lowest fan speed.
1 ½ = higher speed.
2 = next higher speed.
2 ½ = next higher speed.
3 = next higher speed.
3 ½ = next higher speed.
4 = next higher speed.
4 ½ = next higher speed.
5 = this is highest fan speed.
5329112466_d7bf9aa243.jpg


The fan has 9 speeds.
Picture source… http://www.mbclub.co.uk/forums/interior/102041-what-going-my-w202-heating.html

Dec
 

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