[suddha]

I've got a 1990 Spider Graduate (S3 body, S4 mechanicals). Lately I've noticed that both of the electric radiator cooling fans run nonstop while the car is running, from the time I start it to the time I turn it off.

I did some troubleshooting, with the following findings:

- I unplugged the wire to the passenger-side fan. Both fans still run.
- I unplugged the wire to the driver's side fan (goes into the frame). Driver's side fan stops. Passenger side still runs.
- I removed the relay on the fuse panel and both fans don't run. Engine predictably runs hot.

The car has an A/C switch and temp rheostat on the console but I never use it and I suspect the compressor won't even start given the car's age.

Is the relay stuck closed? What am I missing?

Thanks for any help.

 

[Gubi]

Don't have the wiring diagram in front of me at the moment, but sounds like you've either got a stuck relay, a stuck temperature switch on the radiator, or a stuck A/C pressure switch at the receiver/drier. All can be tested for continuity with an ohm meter. Or just put the relay back in and unplug the other two switches one at a time to see if anything changes.

 

[suddha]

Don't have the wiring diagram in front of me at the moment, but sounds like you've either got a stuck relay, a stuck temperature switch on the radiator, or a stuck A/C pressure switch at the receiver/drier. All can be tested for continuity with an ohm meter. Or just put the relay back in and unplug the other two switches one at a time to see if anything changes.

Thanks for the quick reply. I suspected a stuck temp switch on the radiator but wouldn't unplugging the wire that runs from the radiator switch cause the fan to shut off? It didn't. The only thing that shut off that right side fan was pulling the relay. I'll try unplugging the AC pressure switch. Any help on where to find that?

Can one find Alfa relays at Autozone, etc.?

Thanks again.

 

[Gubi]

Yes, unplugging the radiator switch would turn off the fans IF the switch were stuck. If you unplugged it and the fans still ran then the switch is not your problem.

The A/C pressure switch is at the front right of the car, up under the bumper area, you can see it from beneath. It's at the top of the black cylindrical receiver/drier and has two plugs coming off of it. Unplug them both and see if that makes a difference.

I'm a little puzzled as to your statement that unplugging the passenger side fan didn't make it stop. Each fan is independently fed 12V from the relay and has its own ground. Unplugging either wire to a fan should most definitely turn it off. Perhaps you unplugged the ground wire and the fan motor body has a connection to ground or something...make sure you unplug the +12V wire (and don't let it short to anything)

In any case, if unplugging the switches doesn't fix things then it's quite possibly the relay. Unplug it and test with a voltmeter: you should not have continuity between terminal 30 and either terminal 87.

The relay is a dual 87 (two outputs) with an integral fuse. A standard relay (with one 87 and one 87a) won't work, you'd need to match this specific type. You need dual 87s and the fuse is an important safety feature.

 

[suddha]

Thanks, Gubi. I have ordered a replacement relay after calling a couple of shops. Apparently, that part is discontinued so I was fortunate to find one. I'll give it a try. I did notice that yesterday, a cool day after the car had sat for a couple of days, the fan was not running when I first started the car. But it did stay running endlessly after I got home. Makes me wonder if the relay opened/unstuck or if the thermoswitch is faulty and requires a very low water temp to shut off the fan now. That will be the next step after seeing if the new relay solves it.

 

[Tifosi]

I have ordered a replacement relay after calling a couple of shops. Apparently, that part is discontinued so I was fortunate to find one

Not discontinued at all, but likely not showing up as Bosch anymore, rather Tyco instead if the parts computers are updated properly.

Barring the local parts counters which usually seem kind of cluless in general, locating a Bosch authorized electricals repair shop (as in not the garage that changes the starter, but the shop they send it to to get rebuilt) would be a good plan as they can get any and all of the associated relays, including the uber expensive drive relay, just by supplying the part #