1985 535i blowers do not work until i ....

[smoore1127]

Hello all

I lost power to my heater and ac blower a month ago. I changed fuses several times and still no power. Yesterday, i took 12 guage wire and connected the two fuses (ac fuse and aux fan) and bam! my heater blower and Ac came on. Can i continue to run them like this? what could be my problem? should i put in an inline fuse? help its hot!!!!

[mderienzo]

I lost power to my heater and ac blower a month ago. I changed fuses several times and still no power. Yesterday, i took 12 guage wire and connected the two fuses (ac fuse and aux fan) and bam! my heater blower and Ac came on. Can i continue to run them like this? what could be my problem? should i put in an inline fuse? help its hot!!!!

Can you clarify what you did with the wire - did you short across each of the fuses with it or did you bridge the two circuits? Which fuse #s are we talking about and when you lost power, did a fues blow at that time? Are both blowers not working? What is the build date of your car or last 7 of the VIN?

If you shorted across the fuses, then the problem could be with the fuses or their connections in the fuse box.

If you bridged across the two circuits and that ‘fixed’ the problem, then you probably have an issue with an upstream relay, fuse or other circuit not allowing power to the fan or A/C circuit. Bridging them completed some circuit by bypassing the upstream component or circuit that is malfunctioning. (this is what happened if your Heater and AC blowers both came on at the same time) If both blowers are not working, have you checked that your fan speed switch is good?

Either way, shorting across fuses or bridging circuits with wire in a way that they were not designed could at least cause irreparable damage to wiring or electronics or at most cause a fire. Even for testing purposes, I would hesitate to bypass fuses or bridge circuits with wire even if you use a fused link.

If you don’t already have one, I’d suggest downloading an ETM for the car and start tracing / checking circuits that power the fuse / blower in question.

HTH,
Mark

[smoore1127]

thanks for responding: this is what i did

1. I took a piece of 12 guage wire and bridged the fuse for my AC with the Fuse for the Auxillary fan.

2. i cut the car on and pushed the ac button. the blower came on. then i cut it off and cut on the heater/fresh air blower and it worked.

3. the fuse for the AC blew and i replaced it. Then it stopped working and my heater / fresh air blower also.

4. the fuses are 25a. not sure what fuse number is (on fuse box) did not drive my car to work. can let you know tonight...

5. i have not checked my fan speed switch, but it worked when i bridged the fuses

6. will check wiring using etm and let you know

[smoore1127]

I have used my AC and my heater blowers since my last email. No issues. ultimately i need a new fuse box. it appears that these two fuse locations are bad. Anyone know where i can get a fuse box?

Bridging the two fuses with the same size fuses maybe a inexpensive option to replacing the fuse box....