560SL Weak A/C; Weak Blower
 

Hello,

I have 19886 560SL with 133k miles. I have recently had the Climate Control Unit (Klima Control) replaced. In addition, I have checked the refrigerant and it appears OK.

The issue is as follows, when the A/C is engaged, it only blows a very weak stream of air. To be clear, by engaged I mean:

- Fan speed is on high (i.e., the top of the three fan speed buttons is pressed)
- The temperature control wheel is set to max cold
- The middle of the five fan control settings is pressed.

I do feel cold air coming out, just not strong. Since there is at least some air coming out, perhaps the blower is malfunctioning, but logically it seems it is not completely shot.

In addition, I do hear the compressor kick on and the air is cold, so I think the compressor can be ruled out.

Is it possible that the temperature sensor is bad, causing the fan not to blow hard as it think the cabin is warm already (admittedly, I find this unlikely).

Wondering if anyone has encountered anything similar and if you have any ideas regarding troubleshooting.

Thanks all!

srmurp

What is the history of this car? Did the fan ever blow strong?

Does the fan motor sound like it is running full speed?

Have a look at the motor plug, perhaps it was miss wired at some point and is running backwards. ( A centrifugal blower will still move air in the same direction but maybe not as much. )

I wonder if there is a cabin air filter on this car and it is clogged.

Past that, someone would have to post a duct diagram as there is a chance the flaps are not in position causing restricted air flow.

Thanks for your reply. Yes, the fan did used to blow strong.

I have not yet looked at the motor plug or the cabin air filters - but will definitely look into that. In other vehicles I've had the cabin air filters be the culprit - anyone know where the cabin air filters are in the 560SL. (I've done some googling with little luck.)

Thanks, all.

Just did a little bit of diligence on the forum -- looks like there is no cabin filter on the 107:

Here is the link: http://www.peachparts.com/shopforum/sl-forum/187127-107-ac-filter.html

Don't forget about vacuum pods taking a dump on you. If you have vents open that shouldn't be, the air stream blowing out of the dash vents will be pretty wimpy

A considerable stretch of the imagination might bring the conclusion that having the Climate Control Unit (CCU/Klima) replaced had an effect on the fan performance. The CCU does control the fan speed.

I did a bit of research today, few things I'm going to look into are the blower fan resistors and the associated gang plug as well as the ignition.

I've heard that sometimes there is a bad connection between the ignition and the blower which causes the blower to malfunction.

With respect to the vacuum pods -- could that cause the blower to blow weaker?