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Discussion Starter #1
This car is new to me, so I am just learning....Anyway, when I got it, it had just had a new alternator and belt put on. The belt was squeaking. Long story short, the shop that put the parts on stripped out the tensioner adjusting bolt and said nothing about it. I found it, studied up, bought the parts and started putting them on. Of course, all went well until I put a air ratchet head thru the radiator.:rolleyes:...I bought a new radiator, put it in, filled it, and drove the car a couple of miles. All seemed fine. Drove it a couple of more short trips, everything working. During last trip, the blower was running fine on high. I cut it off and it would not come back on. I have checked both fuses. They are good. h\Have I missed something. I did not really "burp" the cooling system. Is there a sensor somewhere that keeps the fan from coming on till the coolant is warm? If so, air pocket?....Or is this a concidence and my blower motor, regulator or control panel just crapped out suddenly?
 

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I believe that the blower circuit is hooked up to the coolant temperature sensor so you will not achieve max blower speed unless the coolant reaches close to normal operating temperature. There are 2 coolant temperature sensors on the top of the head... I recently replaced the one that controls the auxilary fans... very easy repair.

The other possibility is that your blower motor is seized up after 20 years. This is a very real possibility as I looked at the service records of my 90 300e and the blower motor was replaced about 12 yrs into its life. (My car was a TX car all its life too!).

MercedesShopWiki: Blower Motor Removal

R&R of the blower motor looks straight forward with the exception of taking the squirrel cages off the motor shaft.

Good luck.
 

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One other thing I would suggest is that you get the coolant system pressure tested (at the expansion tank) and spend $10 for a new expansion tank cap.

That $10 might be the best money you invest in the car for years to come... trust me, I know from experience.
 

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Discussion Starter #4
One other thing I would suggest is that you get the coolant system pressure tested (at the expansion tank) and spend $10 for a new expansion tank cap.

That $10 might be the best money you invest in the car for years to come... trust me, I know from experience.
Are you saying that there is a connection between the coolant system pressure and my blower not working?
 

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There is no connection between the two. Double check both the fuses. Especially the strip fuse. It can "look" OK when in fact there can be a hairline crack.

Good Luck,

Jayare
 

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There is no connection between the two. Double check both the fuses. Especially the strip fuse. It can "look" OK when in fact there can be a hairline crack.

Good Luck,

Jayare
Nope there's no connection but on older cars the expansion tank caps usually fail to hold 20 psi of pressure which can lead to engine overheating, boiling coolant in your heater core, coolant overflow in your overflow tanks and other nasty things... my point was a $10 up-front investment in a new expansion tank cap will save you alot of potentially expensive hassles down the road.
 

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Discussion Starter #7
The fuses were the first thing that I checked earlier this week. They were fine. I took the strip fuse out, checked it, and found power on both sides. I even bridged the gap between the screws. No blower.

For the past couple of days, I could hear a bit of air in the heater core. I ended up pulling the heater hose where the coolant goes in, bleeding the air, and filling the core from the hose with coolant, and then filling the hose back to the head with coolant before reconnecting........Strange thing....as soon as I did this, the blower started working. I drove the car to work this morning. High, low, and auto were working correctly.....Go figure.....Anyway, thanks to those who replied.
 

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If there really is a connection between burping the cooling system and getting the blower to work it would be news to me. Let us know if this is a final solution. My money would be on the ignition switch.
 

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Discussion Starter #9
I doubt if in my case it would be the ignition switch. At the time, it quit working the car was running. I simply switched the blower off of high and it would not turn back on. The ignition switch had not been moved. Matter of fact, after it quit. I left the high button pushed in. I'll bet I started the car 50 times over the past week while either driving it, working on it, or simply moving it around the driveway. Never once did the blower kick on.

I agree, the air in the heater core should have nothing to do with it. I just know that once I got the air out. It was working correctly.
 

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Also, have you done a capacity check of your battery?

I ran down my 8 yr old battery the other week (won't hold a charge if the car isn't used for a few days) and noticed that the blower was "on" even if I tried to turn it off. I think maybe the blower switches are voltage sensitive and if you don't have enough juice the controls won't respond.

Just a thought.
 

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Discussion Starter #11
No, I did not test the battery. In my case, I couldn't see the need. First the battery is less than 2 months old and starts the car fine. Second, the blower controls should have been getting enough juice. I had the car running alot while checking the blower, plus drove it a good amount. It never worked until I burped the heater core.....I guess just an odd coincidence that it quit when I got air in the core and started when I got it out......Thanks for the reply the tip about the low battery, though.
 

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When the blower motor acts up again, there are two main area's that could be a problem. Taking for granted that all the fuses are good, you have the blower motor and the blower motor regulator. The power feed to the regulator is a large 3 prong plug that is located almost on the firewall just behind the power brake booster.

There is a very good blower motor R/R DIY article at Mercedesshop.com Click on the resource tab drop down to find the DIY section and go from there. Start to finish, it's maybe a three hour job if you've never done it before. Nothing special needed in the way of tools.

The big money hit here is the blower regulator. Most online sources have them for a tic under $300. U Pull yards are going to let you walk for less than $10. I would suggest getting a head start on the project by reading the DIY article and getting your ducks in a row.

Good Luck when the time comes,

Jayare
 

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MercedesShopWiki: Blower Motor Removal

R&R of the blower motor looks straight forward with the exception of taking the squirrel cages off the motor shaft.

Good luck.

I just R&R the squirrel cages off my old blower motor. What a B*TCH to do, but it's done.

ADVICE: before trying to remove the squirrel cages, spray them with something like WD-40 for a few days to loosen it up abit.

This is personal experience.
DO AT YOUR OWN RISK AND DISCRETION.

To remove them, I held the lower cage down with my feet and SLOWLY twisted the top cage off taking care not to put too much pressure that could break the plastic cages.

For the other one, I inserted a flat head screw driver into the old motor to prevent it from rotating when I twisted off the other cage.

To install them back, I replaced the old cages on the new motor as far as I could manually (which was probably 1/2" in only).
I then took a lug nut wrench adapter which fit over end of metal pin and squirrel cage. Tap the lug nut with a hammer as needed, which should push the cage back down on the pin, to the original distance.
For me, it was 5/16" from the end.

Good luck with your personal experience.
 

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Well, I spoke too soon.
After replacing the blower motor, I still have no fan :-(

I replaced my blower motor and I tested it before installation so it works.
When I installed it back in, I tried to test it again before complete installation of the wiper motor assembly, et al.

NO FAN !!! It did not respond to high, low, auto ??????
The 30A strip fuse and fuse #7 within the fusebox were replaced; battery is less than year old and no problems starting car.

Reading other members comments, it appears it leaves the blower motor regulator or the Climate Control (CC) unit.

I think the CC unit works since warm air comes out of the vents on the various selections when the car is moving, just no fan - OR does that not mean anything??


Jayare had a similar issue and his was a faulty "fan speed regulator".
What is a "fan speed regulator" and where do I find it?
 

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Discussion Starter #15
When the blower motor acts up again, there are two main area's that could be a problem. Taking for granted that all the fuses are good, you have the blower motor and the blower motor regulator. The power feed to the regulator is a large 3 prong plug that is located almost on the firewall just behind the power brake booster.

There is a very good blower motor R/R DIY article at Mercedesshop.com Click on the resource tab drop down to find the DIY section and go from there. Start to finish, it's maybe a three hour job if you've never done it before. Nothing special needed in the way of tools.

The big money hit here is the blower regulator. Most online sources have them for a tic under $300. U Pull yards are going to let you walk for less than $10. I would suggest getting a head start on the project by reading the DIY article and getting your ducks in a row.

Good Luck when the time comes,

Jayare


Well, I have driven it 700k miles since it started working again after whatever happened with the burping of the radiator. It worked flawlessly, including the CC unit.

However, I do have my ducks lined up for the if and when it happens to go out again. I have both a regulator and a CC unit that I got off of eBay for spares.
 

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Well, I spoke too soon.
After replacing the blower motor, I still have no fan :-(

I replaced my blower motor and I tested it before installation so it works.
When I installed it back in, I tried to test it again before complete installation of the wiper motor assembly, et al.

NO FAN !!! It did not respond to high, low, auto ??????
The 30A strip fuse and fuse #7 within the fusebox were replaced; battery is less than year old and no problems starting car.

Reading other members comments, it appears it leaves the blower motor regulator or the Climate Control (CC) unit.

I think the CC unit works since warm air comes out of the vents on the various selections when the car is moving, just no fan - OR does that not mean anything??


Jayare had a similar issue and his was a faulty "fan speed regulator".
What is a "fan speed regulator" and where do I find it?
The fan speed regulator feeds current to the blower motor. It is a pie shaped piece that sits directly under the blower motor. Two wire leads come from it to the blower motor. Once the blower motor is out, I recall that there are 3 torx head screws that need to come out in order to raise the blower cradle high enough to remove the regulator. Get an eye on it and you'll figure it out pretty quickly.

Good Luck,

Jayare
 

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The fan speed regulator feeds current to the blower motor. It is a pie shaped piece that sits directly under the blower motor. Two wire leads come from it to the blower motor. Once the blower motor is out, I recall that there are 3 torx head screws that need to come out in order to raise the blower cradle high enough to remove the regulator. Get an eye on it and you'll figure it out pretty quickly.

Good Luck,

Jayare

Hi Jayare,

Is the blower motor regulator and fan speed regulator the same thing?

Do you recall where the 3 torx head screws are? I can't seem to find them.
I see 7 - 2 at the front of the blower motor cover; 2 underneath where the blower motor sits; and 3 at the back of the blower motor cover near the passenger cell.

I found part # 1248212151 - Blower Motor Resistor/Regulator; Heater Fan Resistor/Control Unit made by Kaehler (KAE) for $172 new on autohauz and $290 from Germanstar.
Is this an OEM or aftermarket manufacturer/part?

There's also Behr Blower Regulator 1994-1995 Mercedes Benz E320w/ Dust Filter. NLA 7.08 W0133-1599074 for $206 from partstrain.

Alternatively, I could go to a pull-it yard but it'll be alot of work dismantling the wiper assembly, etc to get a used part that may/may not work.
Is there a way to test it?

Thanks in advance for everyones input and help !!!
 

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FYI - I found the following info by Saumil regarding the blower motor regulator:


If the blower motor control is like my 87, 260E, then the following occurs:

The pushbutton control unit determines what speed is ideal for the temperature setting you have and the temperature in the car, it sends a control voltage to the fan's regulator which inturn sets the speed of the fan.

So if your fan speed was not getting to high, then the problem could either be in the control unit or donwnstream of the control unit. And this can be seperated out by checking the voltage that the control unit is sending.

There is a 3 pin connector that is under the hood, right behind the fuse box, towards the windshield. Remove the cable (these cables go to the blower motor regulator). Run the car. Connect the ground terminal of your voltmeter to battery ground. With the positive terminal of the voltmeter, check each pin. One of the pins should have close to 12V. One of the pins should have 0V (it is a ground pin) and the third pin is the control voltage from the push button unit.

When you press the low fan switch, you should get about 1V. When you press the high fan switch, you should get between 6 and 10V. When you press auto and defrost, you should get about 5V. Higher the control voltage, higher the speed. Infact, you can yourself send the three voltages on the wires that you disconnected and see if you get a variable speed all the way from low to high. Just dont exceed 10V on the control pin.

If you dont get these voltages, the pushbutton unit is not working. Otherwise, the problem is downstream. The blower motor regulator (and also the blower motor) is an extrememly reliable part compared to the pushbutton unit, so my thinking is, it is the pushbutton unit.
 

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You have it right on the part. It's your choice to go with a new part or one from a pull it yard. In my case, I decided to go the pull it route simply because of not being able to generally return electronic parts. I gave up $8 for the regulator plus my $2 entry fee to the yard.

Just look closely at the cradle assembly. The screws I mentioned are located towards the front and there is a single screw that holds the regulator into position. On the bottom back side of the regulator there is also a "pin" that fits into a slot position. Hence the need to raise the cradle a sufficient distance to get the pin to raise out of the slot so you can roll the regulator on it's side and remove from the left side opening. Again, just study what you see and it will become clear what to do.

Good Luck,

Jayare
 

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Before you spend money on the regulator (which could be the problem), please try this first. It's free and easy; the regulator is expensive and a PITA!

As Tuttebenne suggested, it may be your ignition switch. Turn the key to the Run position (2 clicks right, but not start position). Does the fan run? If not, try wiggling the key slightly left and right and see if it kicks on. If not, go for the regulator. But if the fan does blow with the ignition in the Run position, now start the car, and I assume the blower will quit. With the car running, turn the key slightly to the left and you will feel a soft click, and the blower should come on. If it does, your ignition switch is wearing out. But having to make a small change to your starting routine is a small price to pay to be up and running again!

I discovered this the hard way after painfully running through all the tests in the shop manual and then tracing the wiring diagrams, which led me to the ignition switch. I wiggled it, and couldn't believe it when it came on!

I sure hope this works for you.
 
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