rscruggs2

I hope I'm in the right place! I just purchased a 1999 SL500 with 22K miles and have a issue. Saturday, I drove from my farm in North MO to Kansas City with no problems at all. Then in the afternoon with the temperature around 95 degrees, My son and his wife took a test drive and the AC blower shut down. We put it in the garage and Sunday morning I drove back to the farm (130 miles) and the AC worked just fine. Could this be a bad resistor or something along those lines? It would seem improbable the blower motor itself would be failing at only 22K. I hope I don't have to ship it back to Sindelfingen for repairs! Your thoughts appreciated. Here is the car. Regards, Rick.

SRHsl600

Nice toy, great area! I think sending the car back home may be less expense that Aristrocrat, but that's just my history!
Age not miles is the factor most notable. Often getting the diagnostic info from the control box is the best start. The car has several connection places for diagnostic information. The climate control LCD is one place. The ECU, under the engine hood on the passenger side is another. The owners manual has the procedure, as well as this forum or Benzworld. A good modern mechanic will have the reader of most of the systems. My old R129 has a transition from analogy and digital, so two different readers are necessary, but your late model is entirely digital.
When heat related events happen in my Benz, it was vac system related. I also found during servicing the blower fan mount, that the heat sink blower fan and control module that lost its CPU paste ( looks like a tooth paste like film between the sink and motor ). when I was putting all that back together I added a new layer of that paste ( radio shack ) and the control of the temp and fan speed became more responsive!
Air movement is controlled by the temp sensor, electronics of the AC contol, in the instrument stack and the vac from the engine opens the vents to direct the air movement. You can press the button ( red or blue ) in the center vent to have the desired from the center vent.
Welcome to the "love-hate" relationship of MB

rscruggs2

Thanks for the info. It's not a compressor or vac problem as it WAD now. Is there a resistor between the blower motor and switch or is there one attached to the motor? I would say something overheated and that sounds like a resistor problem getting weak to me. I also cleaned cabin the air filter located on the rear of the engine and it looked like it had never been removed....it wasn't real dirty but it was grungy. Where is the access to the blower motor? I would rather change a 34 dollar part myself than drive 135 miles to KC. Regards, Rick.

SRHsl600

After you remove the filter, the wiper motor ( set it to the side ) the plastic air screens that keep debris from the cabin air intake, and disconnect sections of the fire wall, you can remove the top from the blower motor housing. There is a detailed write up with photo's in Benzworld under the "blue stickies" under blower motor strap.
In the process,( took two sessions, separated by several days for parts delivery) I cleaned, lubricated and reconnected the tubes ( vac ) and wiring. It is nice to have a "car barn" with lift, lights and HVAC and a wife that does not expect the garage to be clean for her " inspection"
Good luck with your new toy

KipF

Great find and a beautiful car! I had a similar issue with mine that only required a new filter. It's just as SRHsl600 described. Two questions: What does the ambient temp show? Did they put the top down when they drove it?

rscruggs2

I ran the diagnostics and the evaporator temp sensor is bad. I ordered one from Autohaus for 41 bucks delivered and it should be here by Monday. Keeping my fingers crossed! Regards, Rick.

KipF

Glad you got it sorted out - and even happier for you that it's just a $41 fix!

Chetter

Ahoy to all: I just returned from a 4 month hiatus to Wi, Mn, Nd, Sd, Mo, Ia.... in MH not my 1995 SL500. When I started my MB I immediately realized my AC blower squealed on # 3 and 4 but will not blow "air". I have read the previous posts and have recovered from my "shock and awe" however, where should I start? The temp here in south Mississippi is topping out at 95 degrees. When I turned the ignition switch on the outside temp gage read 118 degrees, which I know was not correct as the car is under my carport although the afternoon sun does shine onto the "bonnet" or hood as we call it. Chetter sends

rscruggs2

The evaporator temp sensor came today. Now I have to figure out how to remove the panel under the dash. It looks like 2 screws and a large plastic keeper of some sort. Anyone ever removed this? The sensor simply plugs in to the system but getting to it may be a big headache. Regards, Rick

rscruggs2

Well, it wasn't the evaporator temp sensor so the next step is the blower motor regulator. Where is it, how hard is it to replace, where can I buy one and who do you recommend? Regards, Rick.

SRHsl600

I wrote about the blower motor work. In another forum called Bensworld there is a DIY with many photos in the 4th line down on the R129 section "Blue stickies" that will show you the way.
I did not replace the fan motor heat sink, but did place "cpu" paste between the surfaces. Almost every issue with the Climate Control system has returned to normal! The paste dries out and "disconnects" the sensor surfaces.
Good luck with the project