240D acting up...

[Plantman]

I drove my dad's 240 today and noticed the ac was acting a little quirky.

It was blowing nice and cold at level 3, or high. Out of nowhere, it suddenly started to blow slower and slower and slower until it got so hot I had to lower the windows.

Drove like that for about 15 minutes, got out and when I returned to the cat, it started blowing normal again.

Between today and the last time I drove it(2 weeks ago) I noticed that the clutch is engaging lower than before.

I'm thinking blower motor and perhaps clutch adjustment?

Thoughts?

[leathermang]

Do you think the blower motor is wired to give you an indication as to when the clutch needs adjusting ?

[Plantman]

Originally posted by leathermang
Do you think the blower motor is wired to give you an indication as to when the clutch needs adjusting ?

That reminds me of the "anti-vibration wire" comment you made a few months back when I was questioning some "shakes" in the SDL.

I actualy think the blower motor is acting weird because of the low clutch pedal.

[leathermang]

I am not sure about this....
but usually when a clutch wears it starts engaging HIGHER and HIGHER....looking at it from the foot pedal point of view....
So I think you need to check your hydraulic clutch fluid and linkage to the clutch first...
On the blower motor.... I think some good threads exist on this....but you could take it out and try getting some (one drop on each end actually getting to the bearing) sewing machine oil or the likes to the bearings.... see if there is a spring loaded oil hole... that would be even better... one drop each end per year is average..... don't want any to get to the windings, etc....

[Plantman]

Leathermang, thanks for the tips. I had no idea you had to oil those things.

Would something like marvel mystery oil work? Or WD-40?

[Rick Miley]

The blowing slower and slower and then recovering after 15 minutes sounds exactly like the evaporator icing over. Greg, does the 240 have an evaporator temperature sensor?

For the clutch, check the brake fluid level. Also check that the supply hose is firmly seated in the master cylinder. It is held in by a rubber grommet that can let go when it gets old. A PITA to get to, but an easy fix once you're there.

[leathermang]

OK,, I was assuming ,,, which is always dangerous...
Is your blower motor actually running slower... or are you saying that you get less and less air from the vent.... if the latter then I think Rick may be correct....
For oiling I would stick with something like Singer Sewing machine oil... or get one of those special oiler pen sized deals...I think several people make them ... with Mobile one, or such special lubricants... you do not want Automobile oil for that.... If you want to use the Marvel mystery oil I would only use their ' air tool ' oil for this application...

[leathermang]

Rick, on the evap temp sensor.... I don't want to answer that and be wrong... it may depend on which AC system his car has....

it really doesn't seem to be meant for long-term lubrication, and breaks down rather quickly, getting gummy. There are recommendations not to use it to "lubricate" firearms and similar mechanisms.

Greg is correct. There are two possible air conditioning control types for this model. Hopefully it is a manual system.

The manual system shows a temp switch that connects to the control unit, assumably to shut off compressor. This could be called a deicing switch, or cycling switch.

The manual systems that I've worked on have been aftermarket in Euro cars. I expect that this cycling switch has a bulb that is pushed deep into the evaporator. The controller then interrupts the clutch circuit whenever the evap temp gets too cold.

I expect the same thing with a ACC system, but would be a little more complex to troubleshoot. I would start by determining the system type and finding a wiring diagram. You will then have a bit of a project in front of you to find and test the sensor and the controller. First, of course, determine if the problem is the fan or icing.

Good luck,

[Plantman]

Originally posted by leathermang
OK,, I
For oiling I would stick with something like Singer Sewing machine oil... or get one of those special oiler pen sized deals...I think several people make them ... with Mobile one, or such special lubricants... ...

Where do you get soemthing like that?

[JamesStein]

Originally posted by Jim B+
it really doesn't seem to be meant for long-term lubrication, and breaks down rather quickly, getting gummy. There are recommendations not to use it to "lubricate" firearms and similar mechanisms.

While WD-40 works as a light lubricrant I wouldn't use it as such on a long term basis. It works quite well as a cleaner and protectant and a water displacer.

http://www.wd40.com/Brands/wd40_faqs.html

[tenknots]

If your blower is getting slower and speeding up again, it's probably on its way out (try wacking under the passenger side dashboard and see if it speeds up again). Same thing happened to me. Replacing it in my '82 was easy. A new motor was $105 from The Benz Store, probably other places as well. It's possible that it's the fan speed switch also.

I don't know if the evaporator has a temp sensor, but the reciever/drier does.

Clutch is unrelated...unless someone routed the master cylinder to the windshield wipers and the hydraulic fluid leaked onto the muffler bearing which shorted and blew the waffler shaft next to the fan speed switch.

[leathermang]

"Where do you get soemthing like that?"
Your local auto parts store should have any of that stuff... or try TSC ( tractor supply company) in your neighborhood... or harbor freight co.... but I got mine from O'Reilly's auto parts ....

[Plantman]

Well I called my Dad and told him to check the brake fluid and voila! it was very low on both sides of the master cylinder.

Neither he nor I have checked that in the 20 months we have owned the car so I have no reference.

I'll put it on a lift next week and check for leaks though.

Tomorrow I'll see if I can't tackle the blower motor issue.

Thanks guys.