Alternate wiring for AUX cooling fans.


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NOTE: Below was installed in May 2007 with 327/365 but now that I have installed ZZ4 temps never get much above 180. Two reasons come to mind (1) 327 block was full of crap restricting flow (2) old balancer had slipped on rubber and was off by 3-4 therefore timing off. However, adjustable temp sensor worked just fine but I don't need now.

The AUX cooling fans installed with aftermarket (CAA) only kick in when compressor is on. This can be modified by taping into the system (blower) on/off switch as others have done. I took a different approach as I noticed that after a long hi-way run even without A/C on and exiting into traffic my temp would climb fast. NOTE: NEW Dewitt radiator, new hoses, new water pump and G05 antifreeze. Also after shutting engine off temp would go way up. Shame not to have AUX cooling fans not working to help cool in these situations.


So I added an adjustable temp sensor that allows AUX fans to kick in when temp (at top radiator hose) reaches ~215.  This is independent of A/C being on or off although fans still run when compressor is on. I also added a On/Off switch that disables this altogether.


Fans supplied with CAA kit are two (2) VA07-AP12/C-31S FAN (9)". These are hooked together and fasten to the A/C condenser then wired together to act as one.

Wiring per install document

I had previously added a solenoid to carburetor to offset drop in idle when compressor kicks in which is include in below diagram.

Link to Solenoid install

There are many temperature control product on the market. I went with a simple and adjustable version
Flex-a-lite 31147. It consists of a radiator probe and switch.

The probe can either be inserted (pushed) in the radiator fins or inserted in the radiator inlet. I elected to insert in the upper radiator inlet.  I then needed a place to mount all the additional wiring and components that I could easily get to and still not be an eyesore.  I have original CAA relay mounted on front side of radiator support which is in close proximity to upper radiator hose so the logical mounting spot for adjustable temperature control was on the engine side of the support. I then made a series of templates until I found one that fit and looked OK. (see Pepsi Case). Then cut final out of thin aluminum. I drilled a hold in support to route wiring.


Then did a test fit and routed wiring


Painted to make less visible and final install


Final wiring diagram

I elected to wire mine directly to BUSS on the horn relay thus temperature control switch is active all the time. What this implies is even when you shut down engine (key off) fans will still run. This has happen to me on several occasions after 90+ degrees and stopping immediately after exiting highway, fans kick on and run for a few minutes after exit the car. I have my temperature control set to kick on ~215 and it will turn off about 195.  I've never seen temps above 200 while driving so I assume they have not kick on BUT in stop/go traffic after hard run it is possible that they could. With the On/Off switch you can disable this system in it entirety.  You can also wire to a keyed source and will only operate when key is on. Also you could easily add a manual on/off switch and locate is cab of vehicle.  NOTE: Regardless how you install make sure this circuit has nothing else on it and is fused and use heavy gauge wire

Remember this works even if A/C is OFF

Additional Note: My wiring throughout the car was replace recently so I am starting with a clean system (stock). No splices in wiring. Changes to wiring is car is 2 amp fuse on Battery Gauge and install of relay for aftermarket power antenna. I also have a 100 Amp alternator with built-in regulator. This new circuit for fans is fused (30 amp) and isolated off horn relay.