Put this up on R3v but maybe there are electrical gurus here that could weigh in.
1) my original post:
My heater/fan blower motor stopped working after a race weekend with too much time spent on rumbles and gators. My guess is I knocked something loose or broke something, the resistor or something else. I've got nothing on speeds 1-4, but with ignition on I'm getting power (12v+) to the blower switch (GN/BR wire). Started with the switch since I'll have to pull the strut bar and fire system hosing on top of everything else to get to the blower and was hoping for an easier fix.
Car is a 1990 325i. I've got the Electronic Troubleshooting Manual and have been following the System Diagnosis tests. YL to ground reads 0 as it should [since no AC switch]. What has me a bit confused is that I'm getting some voltage (around 5 volts) when I test the connections from the hot GN/BR wire to the other wires (YL, BK, GN, BU) at the blower switch connector where I should be getting 12. When the ETM talks about "voltage not present" does this mean 0 or just less than 12v? If the blower resistor was done should I be getting any voltage reading at all? Just want to know if there's something else I should be checking before I pull things to get to the resistor and the blower motor.
2) my latest: from a few minutes ago:
Finally got a chance to get back to this. I get 11.6 volt at fuse 20 with car in RUN. Battery voltage at the battery is 12.4 with car in off.
Replacing K7 relay with a new one makes no difference. Still get nothing at any blower speed.
Pulled the firewall cover and blower motor cover. Connections to the blower motor are fine, both power and ground connections are tight. Blower spins freely by hand. I pulled the resistor and all of the springs are fine. Safety switch looks a little corroded, so possibly the issue. Put it back in for now.
Just out of curiousity I tried car in RUN, blower on 4 = nothing. With everything still on I decided to check the connections with the multimeter at the blower motor with the blue and brown wire still connected to the motor and everything live. Touch positive to blue wire connector and negative to ground and the blower motor kicks on. Surprised me! Removed the multimeter leads and the blower motor keeps running. Will run on speed 4 and speed 3 but not on 2 or 1. Dies. When I try to go back to 3 or 4. Nothing. Blower motor will not work.
Repeated the above multimeter experiment again just to see if I could make this happen again and got exactly the same results. Runs on speed 4 and 3 and then dies on lower speeds or if I turn key to off and then turn key back to RUN. Blower motor will not run even when I go back to 4.
I was thinking replace the resister pack before the little experiment though this wouldn't explain why the blower motor wouldn't run on speed 4. Now I know that the motor obviously isn't dead.
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Boris3
Put this up on R3v but maybe there are electrical gurus here that could weigh in.
1) my original post:
My heater/fan blower motor stopped working after a race weekend with too much time spent on rumbles and gators. My guess is I knocked something loose or broke something, the resistor or something else. I've got nothing on speeds 1-4, but with ignition on I'm getting power (12v+) to the blower switch (GN/BR wire). Started with the switch since I'll have to pull the strut bar and fire system hosing on top of everything else to get to the blower and was hoping for an easier fix.
Car is a 1990 325i. I've got the Electronic Troubleshooting Manual and have been following the System Diagnosis tests. YL to ground reads 0 as it should [since no AC switch]. What has me a bit confused is that I'm getting some voltage (around 5 volts) when I test the connections from the hot GN/BR wire to the other wires (YL, BK, GN, BU) at the blower switch connector where I should be getting 12. When the ETM talks about "voltage not present" does this mean 0 or just less than 12v? If the blower resistor was done should I be getting any voltage reading at all? Just want to know if there's something else I should be checking before I pull things to get to the resistor and the blower motor.
2) my latest: from a few minutes ago:
Finally got a chance to get back to this. I get 11.6 volt at fuse 20 with car in RUN. Battery voltage at the battery is 12.4 with car in off.
Replacing K7 relay with a new one makes no difference. Still get nothing at any blower speed.
Pulled the firewall cover and blower motor cover. Connections to the blower motor are fine, both power and ground connections are tight. Blower spins freely by hand. I pulled the resistor and all of the springs are fine. Safety switch looks a little corroded, so possibly the issue. Put it back in for now.
Just out of curiousity I tried car in RUN, blower on 4 = nothing. With everything still on I decided to check the connections with the multimeter at the blower motor with the blue and brown wire still connected to the motor and everything live. Touch positive to blue wire connector and negative to ground and the blower motor kicks on. Surprised me! Removed the multimeter leads and the blower motor keeps running. Will run on speed 4 and speed 3 but not on 2 or 1. Dies. When I try to go back to 3 or 4. Nothing. Blower motor will not work.
Repeated the above multimeter experiment again just to see if I could make this happen again and got exactly the same results. Runs on speed 4 and 3 and then dies on lower speeds or if I turn key to off and then turn key back to RUN. Blower motor will not run even when I go back to 4.
I was thinking replace the resister pack before the little experiment though this wouldn't explain why the blower motor wouldn't run on speed 4. Now I know that the motor obviously isn't dead.
Open to suggestions.
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