I just finished replacing the radiator, water pump, hoses, tensioner bolt, belt, thermostat, pressure tank cap, AT front hoses, spark plugs, distributor, rotor, and engine mounts. I also recently cleaned the idle control valve and replaced the adjacent vacuum hoses.

I had thouroughly drained the coolant. After installing all the new parts, I removed the screw on top of the aluminum housing over the thermostat, and dumped distilled water into the expansion tank until it burbled out of that opened screw hole. I replaced the screw, put the cap back on the expansion tank, and started the car. I turned the heater control to 85 degrees. Even after the car had clearly warmed up, the blower never turned on. I think I tried every combination of buttons for the fan and the direction of the vents. The blower never went on. Why?

Try wiggling the key just a touch. I noticed this same thing on the 560, no blower on occassion. Found that every once and a while the key would not fully return to the run position. Slightly moving the key broght the blower back to life.

Also, seat adjustment didn't work when the key was off it's mark.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

I'll try that in a little bit but I've never had this problem before. Just some squeaking.

Am I right that if the fan speed is on auto the fan will only start once the engine has heated to a point where it is capable of providing heat to the cabin?

Am I right that if the fan speed is set to the top button (solid fan symbol) it will blow high speed until manually switched to something else? Sorry for some of these questions, but the car came wihout an owners manual and I haven't tried to get a replacement. All this is for an '89 300TE.

Let me add two things; first, is there anything about redoing the cooling system which would affect the blower? Any type of sensor or something? Does the engine temperature have to reach a certain point?

Second, at one point I held the rpm's at about 1800 for a few minutes. After a while, it sounded like there was water gurgling just under the front dash. That went away after a minute or so. The noise of the engine also seemed to increase as if a cooling fan had kicked in or a pump had started. That sound continued until I let off on the accelerator. Once the car was back at idle, that sound went away. Does any of that sound in anyway related to the blower motor?

I just tried the key wiggle thing. Didn't work. The fan was squeaking before this; maybe it choose this time to die? If so, I wouldn't mind as I was planning on replacing it anyway. I just want to know that that is the problem before spending the money. The real frustration is that I really had fun with the other repairs and the car is so much smoother and quieter. It would have been the perfect repair job with no real surprises. And now this. Anybody have suggestions as to why the blower motor wouldn't work now when it always had before?

I think Mike's on a good track. Had the same problem with our '89 560 and it is the ignition switch. Here's a good test, warm up the engine then turn it off. Set the cabin temp to full or close to it, blower switch to HIGH. Turn the key to the "ON" position without starting engine, if you get blower, it's likely the ignition switch, odd as it may seem. I have a new one in the garage, but my wife and I have both developed good "key wiggle" skill.

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Earl McLain
'02 C230 Kompressor
'89 560 SEL "Frau BlueCar" (retired April 2004)

hans - this may sound stupid, but have you checked the fuse
strip located outside of the fuse box?

If it's not the ignition switch it could very well be your blower regulator switch.

__________________
Reno

'93 300E 4Matic
'98 Nissan Altima
'00 Yamaha Road Star Silverado

Sometimes it is as interesting hearing what people don't say as much as what they do say. Here, I don't hear anyone linking the recent repairs to this new problem. Does anyone see a connection between the two?

In the meantime, I will follow up on the suggestions left so far. And thanks.

a sharp rap with the heal of my hand on the plastic trim above the passenger footwell starts it going just fine.

Look at the #5 fuse in the fuse box.

If your fan is dependent on temp make sure you burp your cooling system. i did a radiator replacement recently and it took several trips to totally get the air out of my system. It would overtemp on the highway but do fine in town. It gradually settled in and now runs 180deg all the time, took several days of topping off coolant.

There should be no direct relation between cooling system work and the blower motor working. This sounds like a set of worn out brushes in the motor. If you can find them in your area they can be replaced. If you check on the top of the firewall to the right of the brake booster can you will see a connector with three wires. The red is system voltage 12 or so, the yellow is the control voltage signal for the blower regulator. It varies depending on the speed setting on the ACC panel, but it should be between 2.5 and 7.5 volts or so (don't remember the exact numbers) The black is ground. Get a voltmeter, unplug the connector and check those voltages (with the key on and either high or low speed selected, or, better yet, select defrost.) If they are OK, then it's the motor, if not, then it's in the ACC module. If your blower is squealing, growling or the like, it is probably the brushes..

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.

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If they are OK , it is a sign that the Regulator is not tripping
on [ the yellow is the trigger] or the motor .

The 12 volts [ black and red] has to get to ground through the regulator, so power at the plug does not diagnose motor/regulator. Could be either.

If the brushes are shorted they will be pulling essentially stall current for the motor. This will trip the thermal protect circuit in the regulator (protects regulator if too much current is drawn or the regulator is asked to dissipate too much heat (look at the heatsink) The regulator will vary the current flow thru the motor to ground. That's why it is in the ground leg of the motor circuit. If the voltages are present on the firewall plug, then yes, it is possible that the regulator is shot. But, you are saying that the blower squeals or in other words, it's working but not very well. This sounds like a motor problem, not the regulator. The regulator is a heavy duty component and not too complicated, or either it's working or it's not.

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.