Auxiliary Fan Resistor Part 000-158-32-45 Specs or Substitute Part

[rinconmann]

The dreaded NLA has hit me hard for my AC system re-work and aux fan issues. Started out thinking my AC just needed R134 refill and maybe seals but found fried wires to the Auxiliary Fan Resistor Part #000-158-32-45 which is spinning at the end of one terminal. NLA and not on Ebay or anywhere and has not been for years as many here know. Can't find a Bosch replacement. Does anyone know the specs on the resistor or can advise on the best "work-around" or current ideas? The wire harness to the resistor is almost fried but still "workable" but the part itself shot. The wires after taping still smoked. Any ideas to test it, fix it, replace it with another resistor ###-###-##-## or know the proper ohms spec? I don't want to light my 94 500 on fire or chance more heat issues. I've got a couple of leads but so far no call back and I don't think I should drive the car in Los Angeles CA with 90-100 degree heat. Thanks in advance.

 

[gsxr]

The resistor rarely fails, but if the terminals are corroded, it needs a good cleaning. Or if the ceramic is broken, a replacement would be a good idea. There should be good used ones on eBay? The OEM is Beru, btw, not Bosch.

I think someone posted the resistance spec somewhere on the forum. I have a NOS one that I can measure if needed.

 

[sheward]

These are very serviceable if the ceramics and the actual coil is not broken as Dave said. Cut the nuts off if necessary and replace both machine screws and nuts.

The wire ends are typically fried but can be cut back and used or added onto with a robust connector.

 

[gerryvz]

I recommend getting a NOS unit if possible, and if not getting a used one in good condition. This part was used commonly on a lot of Benz models, so should not be hard to find at a wrecking yard, either. I have seen them many times on various cars over the years.

 

[gsxr]

Resistance of a new 000-158-32-45 measures 0.4 ohms with my Fluke multimeter.

 

[rinconmann]

Just got back from overseas so will check if it is shot. The mechanic I hired put it back on and left me on my own so I need to remove the horn to get to it and test it. I did notice the fan did not come on when I drove it home and parked it in my garage. A longtime member offered a NOS version so hope he will still have it if it's dead, great member who has helped me a lot over the many years. Rather odd it would go bad given there are no moving parts. Not sure how my mechanic can determine it's bad by just saying the terminals spin and not even test resistance and continuity as he seemed experienced. Perhaps the ceramic went bad. I need to get at it myself this weekend.

So before I test it and the pre and post-resistor power (V and A), what I am looking for? What should be my Voltage and Amp readings at the wire on the front end of the resistor and back? Can I just turn on the AC to fire it up and what determines if the aux fans get juice? In other words, how do I get the aux fan voltage to fire off on the front end of the harness to test the voltage and amperage? Then to test the aux fans themselves what kind of voltage and amp range do I need? This way I can determine who the guilty party is and hope it's the resistor. Thank you guys in advance.

 

[gsxr]

So before I test it and the pre and post-resistor power (V and A), what I am looking for? What should be my Voltage and Amp readings at the wire on the front end of the resistor and back?

I don't know what specific readings to look for. Not sure anyone on the forum has measured this with a "good" resistor.

Can I just turn on the AC to fire it up and what determines if the aux fans get juice? In other words, how do I get the aux fan voltage to fire off on the front end of the harness to test the voltage and amperage?

You can short the pigtail leads from the red pressure switch at the receiver/drier, with the ignition on (or, engine running) this will engage the low speed auxiliary fans, where power is routed through the ceramic resistor. The fans should run on low speed with those leads shorted together.

Then to test the aux fans themselves what kind of voltage and amp range do I need? This way I can determine who the guilty party is and hope it's the resistor. Thank you guys in advance.

I'm not certain of the normal current draw, but from memory the fuse is 15A on low speed (through the resistor) and 30A on high speed (bypassing the resistor), so current draw should be less than the fuse rating.