heater blower / 94 s500 - PeachParts Mercedes-Benz Forum

jejr · #1 01-09-2005, 10:02 PM

my 94 s500 has had intermittent heater/ac blower malfunctions....sometimes wont come on then does.......now it seems to be out competely......any ideas before i try to diagnose the problem?

thanks

mbdoc · #2 01-11-2005, 08:09 AM

There is an electronic blower regulator mounted to the blower motor, failure is a common event!
MB number 140-821-83-51 or 140-821-84-51 with a LIST price OF $304.

JimF · #3 01-11-2005, 11:55 AM

of posts in this forum if you do a search.

A few years ago, mine when out. I posted a picture showing what it looks like.
A/C blower's output is low . . .

SSWEET55 · #4 01-13-2005, 08:31 PM

A very common problem with these cars. If you are interested I have a almost new regulator that was used only for 2 days on a car before it was totaled in an accident. I am sure it was working..I put it in and am sure that it is still in great shape. It will come in the original Behr package with the heat paste as well... It hasnt been a month since it was bought and like they said it was over 300.00. I will take 175.00 and ship it to you for free. Call 1-256-597-2424 or email me at jlpayne@farmerstel.com

Gilly · #5 01-13-2005, 08:51 PM

If the blower always is heard to run but no air flow sometimes, it could also be the fresh air flap servo is disconnected.

Gilly

pcmaher · #6 02-02-2005, 09:07 AM

Gilly, your post sounds more like what I'm experiencing. I hear my blower running, and it's speed increases and decreases with adjustments to the blower control knob. It seems to me that not enough air is blowing out the vents when the blower is on high. I hear the blower really cranking, but the air flow amount does not correspond to the noise. I also noticed that defrost does not blow as hard as it used to. Last problem is that blower blows when engine is cold and heat is selected. This can't be right. I know that I have a faulty left rear heater core temp sensor. Could this be causing that problem?

Gilly · #7 02-02-2005, 10:13 PM

No, the temp sensor doesn't make sense for this blower problem. If it's the fresh air flap servo, it'll blow OK until the fresh air door is tipped up and sucked in, usually it get tipped up by hitting a small pothole or something. You can diagnose if this is the problem a couple ways. First you can simply press the "recirculate" button, and the blower will work OK, although you'll be in recirculate mode. Other way is to shut the climate control off completely and the fresh air flap will be heard to "flop" open, and the system again will work fine until you start driving and the whole process repeats itself.
You could also check to make sure your climate control intake filters are clean.

Gilly

pcmaher · #8 02-03-2005, 08:46 AM

Thanks for the advice Gilly. I'll try those things out.

Gilly · #9 02-03-2005, 09:56 AM

No problem. What happens is if the fresh air flap isn't connected to anything (the clip breaks off is what happens), the normal resting position for tis flap is "open" to allow the doors to close a little easier. Then if you're not in recirc, it'll still be open, but air rushing in combined with a fairly well-balanced door will allow the air to "suck it shut". If the recirc door is also in the closed position, you have a blower motor with no real good place to draw air from. If you simply press the "recirc" buttom, voila, instant air source (from inside the car). I think you can buy just the clip for the fresh air door linkage, need a good parts guy to find it for you. EASY to get access to and replace.
Gilly

pcmaher · #10 02-03-2005, 04:52 PM

Would you have a photo or diagram to post to show me where this is Gilly?

myarmar · #11 02-03-2005, 06:20 PM

I had exactly same problem. Fixed with screw and nylon lock nut.

Gilly · #12 02-03-2005, 06:26 PM

I don't have an image of this, no. Not very computer literate even if I did.
I don't know how much work you've done on it yourself. You just need to remove the wide cover that is removed to get at the blower motor/dust filters, in that area over the cowl, it's only about 4-5 long phillips head screws to remove that cover, and it's on the underside of that cover. The servo is powered by the vacuum line over on the right side of that panel, it opens and closes the fresh air flap, which is part of that panel.

Gilly

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