Cooling fans, previous owners, and assuming too much

gull · Post by **gull** » Sat Feb 10, 2007 5:16 pm

Encouraged by the 60 degree temperatures, I decided to go putter around on my '89 Cabriolet a bit. After spot-cleaning the carpet (mold, ugh) and taking a nice drive through the hills, I decided to poke at the cooling fan wiring. It's always tended to run a bit hot in traffic -- it never overheats, but it runs pretty far over on the gauge and tends to spark knock. Initially I dismissed this, because other A1s I've driven tended to run hot, too, but I became increasingly suspicious when I found out later, A/C-equipped models like mine were supposed to have a two-stage fan. If I'm reading the wiring diagram correctly, the first stage comes on with the A/C, or when the radiator temperature hits 95 C; the second stage comes on at 105 C. I could only ever remember hearing one speed.

So, I started poking around. Sure enough, the fan switch has three leads. I start bridging wires and I can get high speed to run, but not low. Ah-hah. I unplugged the fan connector, and found that the previous owner had replaced the two-speed fan with a one-speed unit. The connector mates just fine but the low speed pin doesn't connect to anything. Tricky.

Lesson: Just because the wiring looks unmolested don't assume a previous owner didn't get creative on you.

So, my options are to replace the fan motor or get a little creative myself. The A/C is inop and I have no intentions of fixing it, and the radiator fan motor is almost brand new, so I'm tempted to bridge the 95 C output of the fan switch to the high speed relay coil, so the one fan speed I've got comes on at 95 C. This is how the cars that originally came with single-stage fans operate. If I do this, I'll make the modification in a way that's easy to reverse, so when this motor wears
out I can return the system to stock.

Post by **Briano1234** » Sat Feb 10, 2007 8:16 pm

sounds good to me.

1lowcab · Post by **1lowcab** » Sat Feb 10, 2007 9:43 pm

i hate previous owners, most are idiots!

let us know how the rewire works out for you... BTW, great detective work.

gull · Post by **gull** » Sat Feb 10, 2007 9:45 pm

Some people hate electrical problems, but they're actually my favorites. I'm good at 'em.

I actually doubt it was the PO himself, because he didn't seem like the type to work on cars much himself. I suspect some mechanic did it to him.

1lowcab · Post by **1lowcab** » Sat Feb 10, 2007 9:54 pm

I suspect some mechanic did it to him.

THE MAIN reason i work on all my cars myself!
idiot mechanics.

gull · Post by **gull** » Sat Feb 10, 2007 10:11 pm

1lowcab wrote:let us know how the rewire works out for you...

The actual "rewire" should be easy...just a matter of connecting a new wire between the existing red/black and red/white wires from the fan switch. I'll probably make this modification up by the fan relay because the wiring is easy to access there.

I won't really know if it made a noticeable difference until the weather warms up a bit, though.

DaisyDub · Post by **DaisyDub** » Mon Feb 19, 2007 3:48 pm

Ok ... tell me more about fan motors ... I know there are problems with mine. First of all, the highest speed does work at all. Second of all, it'll run fine for a little bit and then start going "wwwiiiiiiiirrrrrrr" -- it's really annoying.

Also, when the heat is on, only the center vent pushes heat ... the right and left vents push cold air!!??

I think I should replace the fan, but was told I'd have to take apart the whole dash and that would be difficult ... true??

kamzcab86 · Post by **kamzcab86** » Mon Feb 19, 2007 5:26 pm

First, the radiator fan (discussed in this thread) is a different animal than the HVAC blower fan.

That being said, this problem:

DaisyDub wrote:Ok ... tell me more about fan motors ... I know there are problems with mine. First of all, the highest speed does work at all.

could very well be a faulty A/C relay.

DaisyDub wrote:Also, when the heat is on, only the center vent pushes heat ... the right and left vents push cold air!!??

That's the way the system works. Visit CabbyInfo.com for all the details.

DaisyDub wrote:I think I should replace the fan, but was told I'd have to take apart the whole dash and that would be difficult ... true??

Try the simple, easy fixes first. If all of them fail, then work on the blower fan:
How to repair the blower fan
How to replace the blower fan

Post by **Calimus** » Mon Feb 19, 2007 5:47 pm

Also, AC cabby & Scirocco's have a somwhat hidden and a royal PITA to get at extra fuse for the fan blower.

It basicly sits on top of the fuse block, sometimes it's loose and floating, other times it's still connected. I've had the same issue with both my scirocco and Cristines original cabby. The fuse went bad, and only fan speed 4 would work.

Reason for this is that the other speeds require resistance and the fuse helps with that incase of a short. As were speed 4 is 0 resistance.

If you are having an issue with speeds 1-3, this could be your problem.

However, Kammy's site is about the best around, so hop over and have a look.

gull · Post by **gull** » Mon Feb 19, 2007 6:37 pm

DaisyDub wrote:I think I should replace the fan, but was told I'd have to take apart the whole dash and that would be difficult ... true??

Not the whole dash. A few bits of it. If you end up doing it, just keep saying, "It could be worse, it could be a Volvo 240."

Post by **Briano1234** » Mon Feb 19, 2007 10:33 pm

gull wrote:
DaisyDub wrote:I think I should replace the fan, but was told I'd have to take apart the whole dash and that would be difficult ... true??
Not the whole dash. A few bits of it. If you end up doing it, just keep saying, "It could be worse, it could be a Volvo 240."

you don't remove any part of hte dash to repalce the heater fan... that is on the outside of the car... the screws you need to remove are half outside and half inside... then there is the fan motor connector. tha tis inside

DaisyDub · Post by **DaisyDub** » Tue Feb 20, 2007 10:32 am

Thanks Kammy, Bob, Braino, and "Calimus"!!! I will try all that out!!

Post by **Calimus** » Tue Feb 20, 2007 11:53 am

This is what happens when ya post a question around here. It's a full on assult, lol

1lowcab · Post by **1lowcab** » Wed Feb 21, 2007 12:16 pm

i'll take a step by step pictorial for you this weekend as i'll be replacing mine in the caddy.

Post by **Calimus** » Wed Feb 21, 2007 2:16 pm

Yea, I might be doing the same. The fan in Cristines rocco seems to have bit the big one. Sounds like a playing card in the spokes of a bicycle at 10k rpm's with a bag of marbles tossed in for good measure.

Lucky for me I have a spare. And Ben, the only reason I didn't offer it to ya when you started asking about a source for your caddy was the fact that I knew the rocco's was in the death spiral. Otherwise I would have hooked ya up.