old helpo giver needs help now! blower motor 450sl 1977

[abe g]

Will someone assist in how to repair or replace heater blower motor (motor only) and how too check blower switch on 1977 450sl manual a/c and regulator? Referal to repair or replacement sources appreciated. thanks, Abe G

[bwheitman]

Hello Abe,
I have created a web page on MBCA for the 107 just for you! I put the blower motor install and the AC test procedure here, take a look and let me know if you need anything else.
Best Regards,
Brian

http://www.mbca.org/northtexas/107_technical.htm

[abe g]

Dear Brian: Your pictures and instructions top rate! No I need the nme of a repitable blower motor rebuilder or source (reasonable) for a new one and instructions on how to reassemble to blower fan. You have bann a big help, thanks, Abe G

[abe g]

Dear Brian: I still have intermittant operation on my fan. Before I take it out, what to check? (Manual air and heat) The blower switch seems to operate at all speeds (when it blows) Other times, Nothing!Loose connection somewhere? I have heard about regulator problems , does this model have one? Appreciate any check points before I decide on motor replacement. a/c works fine (when blower works). All fuses checked, removed and replaced#2 and #6. I took apart plugs at firewall , cleaned with contact cleaner, replaced, same problem. Thanks again for you help. Abe G

[bwheitman]

When blower motors go bad they start to draw more amps than they should resulting in shutdown from the control systems, or by blowing a fuse. I would check the power draw from the motor, If it is drawing more amps than is normal then it needs replaced. If it is in the right range check the power to it. If your switch and all other components are working properly I would make a best guess that the blower motor is on it's way out. That is typical of electric motors, they draw more amps when worn and will intermittenly stop working. I think you can clean and replace the brushes in them, but I don't know if you can get the parts if you are in the US. I will look for the normal AMP draw range for the motor tonight when I get home. Good luck!

[bwheitman]

One thing you could do is hook a light bulb up to the power on the blower motor. The light will come on when you switch on the blower motor. It will stay on while the motor is on. When the blower fails (quits working) if the light goes out too that means it is a circuit, if the light is still on then it means the motor is bad. That is a free quick and easy test to determine if the circuit or the motor is bad.
Brian

[abe g]

Dear Brian: I have a probe with neon bulb . Do I have to remove the plug? what pins? Or can I stick the point of the probe into the pigtail? where? (one clip to power, and probe to? Thanks again for your usual prompt reply. Regards, Abe G

[bwheitman]

Well I have never worked on a 107, and I really can't tell from the pictures in the procedures, but the blower motor will likely have 2 wires coming out of it. Unless it is grounded and then one wire. There is that series resistance that controls the speed by limiting or changing voltage I think, you want to get the test connection between there and the motor. The wire closest to the motor. How many wires are coming out of the motor directly?

[abe g]

Dear Brian: Will remove covr of blower unit this weekend. Will get back to you with description of wire location. Thanks again, have a good weekend. Abe G