No power to blower motor, '92 300E.
Thread Starter
Newbie
Joined: Jul 2008
Posts: 3
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1992 300E 4Matic
No power to blower motor, '92 300E.
Hi all,
I recently had the blower motor die for the third time in my W124 '20 300E. The first time, a few years back, I replaced the brushes and it worked for about another year, then died again. The second time, I replaced it with a "used but good" motor. It worked for a couple years and now has died again. I hard wired the blower to a battery and found it still ran just fine, so I tried replacing the resistor with a brand new one. As I started doing more testing, when I turned on the switch, I find that I am not getting power between where the resistor plugs in and where the resistor plugs in to the fan. So now I am thinking it is not the fan, not the resistor, but rather the switch. Is my diagnosis on track? Electrical issues are not my forté.
I recently had the blower motor die for the third time in my W124 '20 300E. The first time, a few years back, I replaced the brushes and it worked for about another year, then died again. The second time, I replaced it with a "used but good" motor. It worked for a couple years and now has died again. I hard wired the blower to a battery and found it still ran just fine, so I tried replacing the resistor with a brand new one. As I started doing more testing, when I turned on the switch, I find that I am not getting power between where the resistor plugs in and where the resistor plugs in to the fan. So now I am thinking it is not the fan, not the resistor, but rather the switch. Is my diagnosis on track? Electrical issues are not my forté.
Member
Joined: Apr 2003
Posts: 188
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From: New Milford, CT
'97 Renntech E60RS
There is only 4 parts to the system, fan, fan regulator (under the fan), 30 amp strip fuse & push button unit in the dash.
If you unplug the connectors to the fan & you don't have any current there (use a test light) and your strip fuse is good, then its either the regulator or the push button.
Get a replacement & known good regulator, plug it in the socket above the master cylinder & see test for current again. If still no current then its your push button unit.
If you unplug the connectors to the fan & you don't have any current there (use a test light) and your strip fuse is good, then its either the regulator or the push button.
Get a replacement & known good regulator, plug it in the socket above the master cylinder & see test for current again. If still no current then its your push button unit.
Thread Starter
Newbie
Joined: Jul 2008
Posts: 3
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1992 300E 4Matic
Thanks for the reply. Since I last posted, I tried a brand new blower motor, a known good switch panel, and neither cured the problem. When you say "30 amp strip fuse" are you talking the fuse just outside of the fuse box, or is this something different?
I seem to have voltage all the way to the regulator, according to my tests, but it is below 12 volts (on HIGH). Is that normal? It is well above 12 (14) at the fuse box.
I seem to have voltage all the way to the regulator, according to my tests, but it is below 12 volts (on HIGH). Is that normal? It is well above 12 (14) at the fuse box.
