Hello,
I have a 92 300E Sportline. Recently during a hot day I was sitting in a drive thru window line and air stopped blowing out of the vents. I could tell that cold air was still leaking out of the vents, it just wasnt being pushed out. This has'nt happened before and it didnt sputter or anything, it just stopped. I checked the push button unit for volage output, all seemed well. Also I can hear it open/close flaps when it is used, so I know that the push button unit is working. I think that narrows it down to the blower motor and i've heard something about a relay that controls the blower motor. How would i go about figuring out what i need to replace? Thanks alot for your time!

Zach Hendershot

Zack;
Check the blower fuse under the hood on the drivers side,it should be a 30amp stip fuse in a black plastic holder.
The fuse should have no cracks and the mounting screws should be tight!
If these are well then you may have a failed blower or control.
M.F.

Mike,
Thanks for the tip, but I did check/replace the fuse. Still have the same problem. Thanks again for your help.

Zach

Check for a vaccum hose leak. Or a cap separated from part of the vaccum line. Happened to me.

Where are those vacuum hose located if I have to check for leaks.

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Edgar
Warminster, PA

Is the fan working or not? Probably either the fan blower or the blower regulator if not. There's a three prong plug on the firewall right above the brake booster that supplies power to the blower. If you unplug it, you can check the voltages being sent to the regulator (which in turn controls the blower).

If the fan is working, then you might have a vacuum problem, but the thing with that is that certain flaps spring open when the elements or vacuum supply fail.

do not overlook a bad ignition switch. when car is running, with fan switch on, turn key back very slowly. if fan goes on , replace switch. if no fan check blower motor and blower control.

Yes, check the ignition switch as benzdoc described. With the car running and fan switched on, turn key slightly backwards. This happened to me a few weeks ago.

Vin

When you guys say fan that's the one in front of the car, or is there a blower fan?

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Edgar
Warminster, PA

If its a blower fan I don't have any hot or cold air coming out of the vents when I turn on the Control Unit. By the way the control unit check out OK when swapped with another 300E owner in this Forum.
Thanks
Ed
Warminster, PA
1990 300E

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Edgar
Warminster, PA

I just repaired this on my 94' E320. If you can use a meter that you can fix your problem. Pull the 3 wire plug off. This is located behind the master cylinder. Check for voltage at the 2 outside terminals not the wiring harness, but the terminals. You should have a voltage with the ignition on and the fan on low. Change the fan to high and the voltage should rise. This is the contol voltage to the regulator and it varies between 1- 7v. Next check the voltage to the blower by placing your meter on the left terminal and the middle one. Should have 12v there. If not then the 30A strip fise is open or your ground is bad. If you do then it's on to the blower and regulator test. You will have to get down to the blower to test it. It should be in the center on the firewall under the hood (I think). Once you get there you can pull leads off of blower and check for 12v there. If you have it, then your blower fails you and if you do not have it then your regulator fails you. I like to jumper 12v from battery to motor for final test. If it runs then the regulator is not grounding the blower properly. The regulator has 4 wires soldiered to it, a small control wire, a 12v wire, and the ground coming in and going out to the blower. You can jumper ground to the regulator(meaning bad ground if works) and jumper ground going to motor(meaning bad regulator if works). I also ran an amp test while testing motor, should have less than fuse rating while running normally. Also check fuse carefully because mine was cracked so fine that I had to push on it to tell it was bad.
Hope I covered everything
JohnT

I will test this out and will keep you posted.
thanks

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Edgar
Warminster, PA