Fan staying on constantly!

[Paulgo]

Got an interesting problem - ater replacing a blown fuse my with my rad fan stays on!

When I replaced the old Nissen rad on my 3B for a Bher unit I also swapped to an ABY fan. Trouble is that the ABY fan doesnt have the same 3 wire plug, just two connectors. To get round this I connected the blue/red and black/red wires from the old plug together and all seemed well.

However, a few months down the line for some reason the fan doesn't seem to be kicking in as it usually did at about 1 notch past 90. When checking the fuses I found the 30amp fuse 21 was blown. Trouble is that when I replaced the fuse the fan runs constantly at low speed (either first or second speed Im not sure), even with the ignition off and the engine cold!!

Its possible Ive not spotted this blown fuse from when I changed rads/fan, the fan only really seemed to come on full speed anyway, but obviously something aint right!!

Anyone got any wiring diagrams for the ABY fan? Got the 3b/7a schematics from S2Central's site which are really helpful but Im trying to work out how an ABY fan should be wired in a 3B as I have either an extra blue/red or black red wire. There's also the inline resistor although it looks like this wired into the blue/red circut somehow. Any thoughts guys?

cheers

Paul

[volcano rs]

sounds like a faulty switch

[K Simmonds]

sounds like a faulty switch

Yep, I'd start with the fan switch.

[nip]

paul i think i might have an old fan switch, il send it ya if ya need it matey

[Mikes2]

can't be the switch as it's only active with the ignition on

It's running in afterrun mode

[johne]

Anyone got any wiring diagrams for the ABY fan? Got the 3b/7a schematics from S2Central's site which are really helpful but Im trying to work out how an ABY fan should be wired in a 3B as I have either an extra blue/red or black red wire. There's also the inline resistor although it looks like this wired into the blue/red circut somehow. Any thoughts guys?

cheers

Paul

The wiring diagrams for the ABY fans are on S2Central's site under AAN. Sheet C50/9 has the diagram for non A/C cars and sheet 75/1 for A/C cars. The difference between them is only in the way the temperature switch in the bottom of the radiator is wired.

It could be that the excessive start current has welded the relay contacts together. Try pulling each of your fan relays, see if the fan stops and check for a short circuit between relay pins 30 and 87.

ABY cars have a speed control resistor pack on the N/S under the washer bottle but I'm not clear from your post if you've fitted that but you must have a resistor somewhere given that you have a slow speed. The ABY pack has two resistors giving ABY cars three radiator fan speeds.

John

[Cesar S2]

aby wiring diagrams

http://shrani.si/f/2l/PK/L7YRZQx/audi80schemaelettrico.pdf

[Paulgo]

Thanks for the replies guys. I am definitely missing the ABY speed relays which looks like its the reason the fan runs in afterun mode with fuse 21 in place! The only one resistor Im aware of is a cigar shaped cylinder thing wired in to the blue/red wiring. Obviously not as straightforward as I had hoped to transplant a 3b fan with an ABY one!!

Now that Ive got both sets of schematics (thanks again guys) at least I can try to figure out what and where I should wire in! Either that or I'll have to dig my old 3b fan out of the loft and most likely pull the rad again to swap em back (third time in about as many months the rad will have been out!! )

Think I might have two problems here - possibly the switch which is the cause of the fan stopping to work at all, (had this problem before due to corrosion on the plug and had to replace all the spade connectors and wiring) and lacking the resistor pack to enable the ABY fan to run properly on a 3b. Not sure if I can just wire the pack in and it will solve this one! Meanwhile, with fuse 21 pulled at least the overun mode is cancelled and the fan can work although only on full speed which is better than nothing!!.

Anyone got a spare resistor pack

cheers

Paul

[yodasfro]

Had this problem with my 200 20v 3b motor it was the afterrun relay gone bad.