Aux fan won't work with AC switch.

[e30rapidic]

yes, another one of these threads. I've scoured the web and the aux fan wiring diagram page in the ETM....

car has a build date of 10/86. I am trying to get my auxiliary fan to work as designed so I can get the S50 AC working. The aux fan gave up years ago so I put in a separate circuit and wired it to a manual switch in the console. I have since hooked the Aux fan back up to the stock wiring in anticipation of having AC...and put a puller Spal fan on to the other circuit.

I understand that when the blue snowflake switch is depressed the aux fan automatically kicks in on low....right? Mine doesn't. In fact nothing happened at all at first so I bypassed the A/C compressor enable switch behind the HVAC panel. I now get the blue light to come on but the aux fan still won't kick on. The aux fan works on both high and low speeds if I jump it at the thermo switch on the radiator. The diode in the fuse box tested out perfectly and the relays/switches are getting 12 volts. All the fuses are good. I've jumped both the high and low pressure switched at the drier.

Any suggestions as to where to look next? I've got the HVAC panel and the kick panel out still to probe about on C204.

[e30kawi]

I'm in for answers, have the same problem.

[jlevie]

Look at the wiring diagrams (http://wedophones.com/BMWManualsLead.htm) and work back from the radiator temp switch.

[e30rapidic]

Look at the wiring diagrams (http://wedophones.com/BMWManualsLead.htm) and work back from the radiator temp switch.

thanks but I have. Printed it out and wrote all over it as I was doing my in car tests. It just doesn't make sense to me why the fan isn't kicking on. I'm getting about 12V everywhere I'm supposed to and the fuse box diode tested out at 0.510 ohms one way and OL the other..so its good.

[vpilarrt]

I assume you have at least one of the HVAC sliders open at least half-way.

[e30rapidic]

tried all 3 in various positions. That shouldn't matter though since I jumped the compressor enable switch that plugs in the slider assembly right?