SLK R171 heater motor blowing but no air

[Mazzo]

I have seen this here on the forum and followed all the advice given in previous threads, however I've not managed to get a solution. It may be because something is not as other peoples experience. Here's what happened.

I bought an SLK 200 2008. It had a noisy fan and this was replaced (I do not know if iut was blowing before or not as I did not have the car at this point). When I got the car, the fan is clearly working but no air is coming out of any vent - floor, sides or windscreen.

I took the motor out and noticed that the old one had worn holes in the casing where the bearings must have collapsed and the fan itself just ground down the plastic. I have repaired these holes and it is now sealed. I was pretty sure that was the problem, however it wasn't. I even took out the pollen filter in case it was too clogged. Still no air.

I can hear the servos changing as I turn the knob for where the air should come out (it's the duel 4 knob type). I can even see the one in the heater housing that blows onto the floor, open and close.

I phoned the seller and he told me he had got a motor from a left-hand drive car. I would have thought all motors turn the same way, but it may be that the vanes are different. Could that be the issue? It kind of seems to obvious but someone on here will know. I have spent some time trying to find photos of LHD and RHD fans - most times they are showing the casings, but it's the fan itself that he has put into the RHD housing.

Other than that, I don't really know I can do any more than take it for a STAR. Not sure my OBD2 will find it.

Any advice would be brilliant. Thank you.

 

[star]

Is it spinning the correct way?

 

[Mazzo]

That is the question. I don't know which way it should spin, so I will take it out but leave it connected and carefully turn it on. I can then see if the vanes are scooping the air or not. Having just (by amazing coincidence) spoken to you this morning - will then invert the wiring on the motor if it is the wrong way.

I'll report back.

For anyone who has suffered the same fate with the housing being worn by the fan itself, here's how I sorted it:

The holes:


Remove the fan from the housing and then put something flat (2 craft knife blades in my case) over the holes


Then tape them down and back fill with a hot glue gun



The end result is totally flat on the inside and completely sealed from the outside.


Final step: clear the dining table and seek forgiveness!

Hope that helps anyone who had a similar issue.

 

[mattkh]

I phoned the seller and he told me he had got a motor from a left-hand drive car.
Any advice would be brilliant. Thank you.

Look at the parts catalogue and check if they show 2 different motors, one for the rhd car and one for the lhd car.

 

[Mazzo]

I haven't got a parts catalogue, but I took it apart again and it is turning in the correct direction. It generates a lot of air movement, so again, I put it back into place but left off the pollen filter shroud. Through the opening from the blower housing, there is plenty of wind coming out. Once the pollen cover is back on (even without the filter) there is basically nothing, even at high speed, through any of the vents.

I can see the flaps moving for the footwell area and hear others moving, but something isn't right and perhaps one of them is closed off somewhere.

What I am curious about is how does this heater do recirculated air? The motor sits directly below the air intake by the battery, yet I cannot see any valves/flaps to close this off it it was on recirculate. I can hear the change in pitch as something somewhere opens and closes as the button is pressed, so I doubt it is this. The airflow through any vent, even at full speed, is a tiny breeze that you can scarcely feel at all.

Would anyone have an expanded diagram of this system or point me in the direction of where I can get one?

I am now pinning my hopes on the SAM unit that is part of the four knob unit. Don't know how to check this other than with a STAR - but I haven't got one!

 

[Mazzo]

Problem solved. It's the vanes. They are pushing the air in the wrong direction (ie towards where the outlet would be on a LHD version. So although some air comes out, it isn't being foced out as it should.

So now to find a RHD version....

 

[star]

Problem solved. It's the vanes. They are pushing the air in the wrong direction (ie towards where the outlet would be on a LHD version. So although some air comes out, it isn't being foced out as it should.

So now to find a RHD version....

As I said, reverse wires on fan motor.

 

[Mazzo]

I did and it works but the vanes are the wrong way around, so it doesn't push lots of air through - but it does enough to clear a windscreen. The RHD fan is a mirror of the LHD, so the vanes push the air into the wrong place. I have now managed to get the old vanes from the previous owner and will try to remove them off the old motor and put onto the new one. If that fails, then it is £300 roughly for a replacement.


It turns clockwise, so the vanes are pushing the air the wrong way for the exit point. At least reversing it gets something out.

So Star was correct. Thank you very much! Also explains why I take my Mercs there. They will get to see this car for the first time when they service it in a month. For now, I have some air but will need to fix it properly however I can risk driving it if it needed to demist the windscreen - which there was no chance of before!