I'm trying to get my cooling fans to run when A/C is turned on.

Background: I have an 86 IROC that was originally a 305 4 bbl VIN code H. Bought the car back after previously selling it less the engine with a bunch of cut wires from ECM. I installed a 350 4 bbl and changed the original v-belt setup to a serpentine setup from a later 80's model (88 or 89). With that, it changed the AC compressor from left side of engine to right side and I upgraded to late 80s compressor and hoses.

In addition, I installed a dual electric fan from a 4th gen camaro along with dual relays I got from Jegs. The fans now kick on at like 190 and off at 165 via the ground from the temp switch closing/opening at the designated temps.

Soooo....I've finally gotten around to hooking AC up and getting it charged but now I need to get the cooling fans to kick on when the AC is turned on as the fans obviously need to run when it's on.

Short of putting a ground to the fan relays on a toggle switch inside the car that could be switched on when running the AC, which I'd rather not do, or running a ground direct from the battery instead of the temp switch so the fans run all the time when the ignition switch is on, which I'd also rather not do, does anybody have an idea how to make the cooling fans kick on when the AC switch is turned on?

Keep in mind a lot of things under the hood had been gutted and the ECM is no longer in play.

I've racked my brain and can't come up with anything but I'm like an ultra-novice at this stuff.

Thanks in advance for any help!

EDIT: How about installing a trinary switch and doing away with the existing low and high pressure switches? It currently only has a low pressure switch on it as I haven't installed the high pressure switch on the compressor as of yet. Thoughts?

 

 

Ahhh! Cool, and, thanks!

Basically, I simply need another relay like the two I have hooked up to the cooling fans with a feed from the AC switch wired like your link indicates with the output negative tying to the negative coming from the temp switch that goes to the existing cooling fan relays?

 

 

On my 84 that I swapped to Serpentine, I simply moved the AC wiring from the driver side to passenger side and the fan worked as normal, kicking on with the AC.

 

Thanks again!

 

. . . . yeah, that'd def been the way to go, but as indicated, the guy(s) who pulled the engine after I sold it the first time did quite a bit of gutting. AC was all gone: AC lines, AC wires . . . all of it, gone. I'm getting it all back together and the AC is actually the last thing (other than body/paint) on the punch list. If I were only as fortunate as you to be able to do what you did to get yours working. haha!

really is a shame the damage the dumbass did to the car . . . it was once a nice one. it will be again. i have it as a solid driver for my kid, now. all new steering components, shocks, struts, bushings, ball joints, springs, rear end, rotors, calipers, pads, bearings, pretty much the entire drive train is new parts, for the most part. had front end aligned yesterday and, wow, car drives pretty nice for a 1986 model.

 

The 86 should have come with a single fan and engaged the fan by grounding the relay lead through the AC control head. If you still have the relay wiring near the brake booster this lead may still be connected. it was the same lead that went to the fan switch on the right cylinder head.

another option is to use the pressure switch that later models used to engage the fan.

either way there is no need for another relay. just add the ground for the AC operation to one of your existing relay control leads.

 

yes, it did have the relay near the brake booster and a single fan. the relay is gone, though. however, the wiring may still be there, I'll have to check that this evening as I'm thinking it still may be. i'm actually using the red/black wire that was the switched wire to that relay as the switched wire to the new relays i installed for the dual fans. I'll run a jumper from it to the temp sender if it is still there and see if it kicks the fan on when i turn the AC on. if not, i've already picked up the relay so will give it a go. if it does, i'll return the relay. thanks!!!!

 

THANK YOU!!! Works like a charm! COLD AIR!! Car hasn't had cold AC in probably 20 years.

I tried to find the ground from the old fan relay to no avail so went with the above and works great!

 

I am doing the same, do you know part number or specs for the hoses, the ones I have found are 4'+ so they can go to driver side