Bennal

I've just upgraded from my CLK320 to a 55 AMG and am having a problem with the blowers on the new car. There is only a tiny amount of air coming out of the vents even with the fan set on maximum. To put it in perspective, my 320 (no climate control but has air con) puts out a huge amount more air on fan setting 1 than the 55 does on the highest fan setting (full climate control).

Having read a some useful posts on blower issues I've had the blower motor out expecting it to be clogged full of rubbish but it looked fine. The fan speed adjustment seems to work as the motor output changes in line with the adjustment. I left the motor disconnected and tested the buttons for changing the fan output type and I could hear the typical clunk inside the dash indicating the outlet was being changed. The pollen filter was changed last week as part of a service.

I've also checked the white vacuum cable in the engine bay and that looks fine. There is a sort of buzzing/hissing coming from the back of the engine bay where the white cable goes into the black one, but I'm not sure if that is a normal thing or not, and it does sound more electrical than air related to me.

Can anyone provide me with an idea of what to check next?

MarcusF

When functioning normally, in its highest setting the blower should be annoyingly loud and move a lot of air. This sounds like the blower regulator is on the fritz. It takes about 15 minutes to change, normal hand tools can be used, and the regulator costs about $100. This link explains how to change it.

tomtomtomtom

Marcus...as usual...unbelievably helpful!

Bennal

Thanks for the info Marcus. To be honest, I'm not convinced the regulator is at fault. The fan speeds are consistent at each fan strength setting, there is no intermittent-ness to the fan output, and on the highest setting the motor is annoyingly loud as you describe. I left the compartment cover off the motor while I tested it, and turning the fans up did displace more air out through the cover hole, it's just not coming out through the vents. I'm going to test the regulator with a multimeter tonight to make sure the output voltages are correct for each fan setting, but I'm expecting that to not show any issues.

I'm pretty sure there is a blockage either before or after the blower motor. Whereabouts is the air intake for the blower? I would guess it'll be down underneath the grill by the windscreen wiper. On a lot of other cars this can get clogged up with leaves and sediment, I'd guess it'll be the same story on the CLK?

Josh K

Where the air is directed is controlled by a vacuum system. Might be a vacuum issue, either with a line or the pump. I had a get a windshield replaced once and the installer broke a vacuum line while putting it in resulting in zero air out the middle vents.

Bennal

I checked the white vacuum cable at the back of the engine bay and that looked fine, it joined up to the large black cable and didn't appear to be leaking. There was a small metal bracket type thing hanging loose off the cable, but I couldn't see where it was supposed to attach so I removed it.

When I press the button for changing the air direction I can hear the typical clunk inside the dash when it changes the output, but the actual airflow doesn't seem to change. Although to be honest, the amount of air it is putting out is so low that it's difficult to tell whether it changes or not.

Is it possible that one of the internal direction flaps has gotten stuck? Is there any way to access these without taking the whole dash out?

City Rat

Until you mentioned the flaps getting stuck i had forgotten that this was one of many problems with an SL that I test drove and had MBZ inspect. The service guys said it was a known problem in that model. There are threads on this forum on the topic as well. Never heard of stuck vent flaps as a problem with CLKs though.