Climate Control System Died Suddenly

[backstage1]

I've had my `88560SEL since Nov.

Although the A/C worked when I bought the car, I've left it
on the Economy setting most of the time I've driven the car.

I hit defrost today, which always seems to kick the fan on
high. I made a brief stop and shortly thereafter, I noticed
the unit wasn't working at all. I don't recall if I turned the
defrost off prior to it stopping.

Now, the fan isn't blowing so I can't tell if the whole system
is down or just the fan. None of the fuses, including #5 are
blown and I checked the strip fuse (as suggested elsewhere
on the forum) and it looks fine, too.

Other threads discuss repairing the climate control system,
replacing the brushes, etc. Most of those threads describe
intermittent problems with the system prior to failure that
helped pinpoint the problem.

That didn't happen for me except that I noticed when I turned
on defrost it seemed to blow high regardless of whether I set the
fan on high, auto or low.

Any advice would be appreciated. I'm a complete newbie when
it comes to this and normally have my mechanic deal with this.
Given some of the parts prices I've seen for the AC control unit,
the regulator and the blower, I'm willing to try some DIY here.

**************.com sells a little DIY kit for the replacing the
brushes on the blower motor for under $40 but I'm not sure that's
where the problem lies.

Thanks,

Bill

1988 560SEL w/131k

Thanks,

Bill

[CzarFC]

Some ideas, although I have a gut reaction for ya.

If the problem is no forced air then it's probably the blower motor. You can sorta check out the rest of the system by setting either max or min temperature and driving at interstate speeds (75mph here in Colorado) and setting the system to blow. If you feel warm/cool air as appropriate being naturally forced through the system by the air intake then the rest of the system is doing what it should but the blower is dead.

If the problem is no air, then the blower motor is probably dead. Did you get any chirping from the passenger's footwell for the past few weeks? Replacing the blower motor in the 560SEL is a real treat let me tell you. This is from the school of been there and done that, although it is easier than my 300CD.

Easiest way is to set the passengers seat in the most reclined and pushed back position possible. Then you'll be working upside down basically holding onto the headrest with your ankles. Once you have the cover removed, the motor is held in by an assembly tha uses 3 screws. Now the joy is goign to be removing the fan to place on the new motor or if you wanted to pay the extra $100 then you're new motor will have the fan pre-attached. Unless you have a dremel, epoxy, wrapping wire, and an overbearing drive to make things difficult, get the motor with the fan!

The rest is basically straightforward, but a little tedious... Not a difficult job, but it will take you the better part of a day if you've not much of a DIYer. I'm sure there's more comprehensive instructions running around, but if you get stuck I'm sure someone around here, including me, will be happy to help further.

I do not envy you the neck and back ache you'll get from this. I suggest ibuprofin or a beer!


Good Luck!


Scott

[meltedpanda]

before removing the fan check to see that you are getting power out of the ACC pushbutton unit. Should be a plug on the fan housing.
Eliminate easy stuff first.
Since the fail safe for the ACC is defrost mode , my feeling is either a fuse, pusbutton unit, or temp/fan regulator.
Let us know what you find

[gidpor]

One other thing to try and cure the "not working at all" portion of your problem is to juggle the keys with the system on to see if that does anything.
Worn out ignition switches will often do just that - disable the climate control System. On second thought - In my car only the A/C was disabled, so that might not apply to your situation - Still, it is a simple test. Also, Also, regardless of whether "None of the fuses, including #5 are blown" I would still replace that #5 with a new one. Fuses are another mysterious thing with old MB's. They might look good - But looks are deceiving.
Hope this helps you some.

[benzboy87]

If you don't want to buy a new blower unit or install the kit yourself then you can get a used blower motor from a mercedes pre-owned parts place (salvage yard, junk yard, whatever you want to call it). I was able to get my fan to work for a couple of months by hitting the area around the fan with the heal of my hand. Might get you through for a while. Good luck, replacement requires a contortionist's skill.

[backstage1]

Gidpor, I replaced the #5 fuse and it had no effect.
Mind you it wasn't a brand-new fuse but a matching
spare that was in the fuse box.

CzarFC, I turned A/C on and drove at highway speeds with all the
vents closed except the driver's side vent. I could feel some
air and the temperature varied from min cool to min heat.

Also, when as I toggled through the pushbuttons, I could
feel the engine adjust as the compressor kicked on and off.
That wouldn't completely rule out the problem being the ACC
unit, I guess just the fan controls could be out.

Prior to this happening, I've heard no squealing or any other
noises from the fan.

Btw, based on the info I've got, how would you know the problem
is the blower motor and not the regulator?

I guess I'll try gidpor's key trick next and then hit it with my hand
to see if that helps. Next, I'll have to round up a meter to check
to see if the fan is getting power.

I just tweaked my lower back yesterday and it hurt like hell just
changing a tire for my wife this morning. I might wait a few days
before I try to pull that fan.

So far everyone has talked about replacing the fan. What about
replacing the brushes? Is that a fairly advanced job?

Bill

[meltedpanda]

brushes are a piece of cake, just need fairly steady hands, fairly good eyesite and a low temp soldering iron

Is your vacuum working? Vents opening and closing?

[backstage1]

Originally Posted by meltedpanda

brushes are a piece of cake, just need fairly steady hands, fairly good eyesite and a low temp soldering iron

Is your vacuum working? Vents opening and closing?

So does replacing the brushes as effective as getting a new
heater blower? If so, that $40 kit with detailed instructions
should do the trick for me. If not, the best prices I've seen are
$151 for the blower and $275 for the blower with the fan
attached.

I'm just hesitant to spend that much time and money only
to find out the problem is in the regulator.

As far as I can tell, the vents are opening and closing. When
I took a drive on the highway this afternoon to see if I could
feel any air coming out of the vents and check if would come
out both hot and cold, I shut down the center and passenger
side vents so everything would come out on the driver's side.
It did.

The back seat vent opened and closed properly as well.

Banging on the panel where the fan is didn't do anything nor
did trying turning the key on an off while changing the cc
settings.

Bill