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aux fan questions

Oct 30, 2001
Glen Burnie, MD, USA
1986 Bright Red Coupe
I picked up a NOS auxiliary cooling fan (RPO B4P) off eBay and have a couple questions for anyone who's got one installed.

1. The blades aren't evenly distributed around the fan. Is this normal? They look like a stick figure (a head on-center, two arms evenly spaced from it, two legs evenly spaced from each other and the centerline but further from the arms than the arms from the head).

2. Will this block too much air to the radiator when the car is moving fast?

3. Is it difficult to install? It looks like two or three screws and a plug, but not sure where exactly it goes (I'm assuming in front of the radiator, blowing air back at it).

I want as much cooling as possible since the car will see track and autocross use.
I took the aux. fan out of my car to make room for my oil and tranny coolers. I'm going from memory here and I'm over 40 so that's not a good thing. The plug to hook the motor to is just behind the left turn signal bulb. There is a wiring harness there and the plug for the aux. fan is a two prong GM weatherpack plug. You mount your fan in front of the radiator and route the plug from it through the shroud over there behind the left turn signal. There are a couple flat areas molded into the shroud for the upper two plastic support arms to bolt to and the center bottom one bolts to the splitter spoiler cross member. I don't know if all cars have that wiring in place or just the ones that were built as Z51's from the factory. If you don't have that plug there you are going to have to do some wiring to set it up. The factory Z51's use a temp sender on the left head to trigger that fan. See if you have that sensor screwed into the left head, I think between 1-3 cylinders. If you don't have any of the factory wiring you need to learn a little about wiring up a relay and a switch to run your fan. It's not hard but a bit too time consuming for me to type here. Good luck.
Thanks, Bob. It looks at first glance like the car is not pre-wired (I've been spoiled by my Legacy, where all options were pre-wired including heated seats!). I'll probably try and snag a pre-owned sensor, relay, and wiring harness and just install that.

There's a plug through a hole in the shroud and no extra wires that I can see. Do you remember, are the mounting screws self-tapping, or are there actually supposed to be pre-drilled holes there with those metal C-clips?

I think there are those metal clips that the bolts thread into. Sorry I can't remember for sure. But, it wouldn't really matter because you could bolt it through any way you want. If there is no factory wiring I would just put in a switch, relay, and fuse. I wouldn't bother with the temp sensor because it isn't that hard to remember to turn the switch on, and you are going to want to be able to turn it on manually anyhow.
I have an 89 with the aux. fan option. I wanted to run my car cooler also. So I put an 200 degree switch on the aux. fan and changed the thermostat to an 180. Now the car almost never needs the main fan to come on and it normally runs under 210 even on the hottest days. The main fan comes on at 220 I believe. I only see these temps on a hot day with the air on and/or idling in traffic.

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