Besides it's normal duties of responding to the radiator coolant temp sensor , which it is already doing fine, I would like my E-Fan controller to turn on the fans whenever the cabin air conditioner is running and shut off when not running (if they not otherwise needed, that is, at that moment, as dictated by coolant temp cooling requirements).

Is there an electrical signal, preferably under the hood somewhere, that changes state depending when the AC gets turned on and off?

I don't think the AC clutch signal is a good choice since I want my E-fan running the the whole time the AC is in use and not just when the pump clutch cycles.

I have gone through the wiring diagrams in the manual, for my year, but haven't come up with anything but maybe I'm missing something.

What do you guys think? How would you sense whether the AC is on or off, electrically? As long as I can sense the condition, electrically, I can incorporate the AC state into my controller, accordingly.

 

Flex a lite makes makes different controllers to do what you want. The one i have you can adjust the point where the fan comes on. It does have it's own temp sensor that you need to put in the upper rad hose. There is a pin for the ac feed as well. You need to tap into the the wire coming out of the hvac unit for the ac and not use any of the under hood ones.

 

It looks like the pressure switch circuit for the compressor is only powered when A/C is requested. Could tap into that circuit without any trouble at all. Just hit it BEFORE either of the switches. (goes from control head, to high pressure switch, then low pressure switch, then to the PCM.)

 

Hi Moparite. I've considered those controllers. I was trying to be low cost and DIY if possible. The Dual fan speed control is very nice and mine wont have that. I figure when I put the 3 core radiator in, hopefully the fans wont be needed much and with both of them running it wont take long to get the temp down so they shouldn't run for a long time either.

HeyYou. That is exactly the type of thing I was looking for. Thank you very much. Maybe I could make a little in line cable adapter, at the high pressure switch so I wont need to cut into wiring harness wiring. I think maybe I found the signal you are referring to in the wiring diagram in the pdf. There is a signal on the PCM connector called A/C request. But I wasn't able to figure out where it went. Unfortunately the pdf for the 1995's on here are not searchable so it makes trying to figure out multi page diagrams like the wiring very challenging. You pointed me right at the money shot. Thank you, sir. Once again.

 

FYI When I pulled one of the pressure sensor plugs to check how it works it with my multimeter today, one lead had key on power but seemed unaffected by the mode of the A/C, unfortunately. Bummer. I don't think that is going to work.

I could do a manual override but that seems lame.

 

I don't understand why you want the fans running anytime the A/C is on. There is plenty of air flow once you're moving. The A/C also runs in the winter when the defrost is on. I think you would be better off tied into the compressor circuit and have a manual switch for if you're stuck in traffic.

 

The reason to run the fans whenever the A/C is on is so the A/C still works efficiently when I am not moving fast enough to get sufficient airflow through the condenser. I'd rather not have to worry about remembering to turn on fans when the a/c gets turned on and I'd also rather avoid drilling a hole in my dash or trying to find someplace else to put another switch.

 

I probably will be adding a manual switch. I just wish I could come up with a cleaner solution.

 

I get what you're after, I just don't think kicking the fans on anytime the A/C is on, is the answer. Like I said, they'll be running in winter when the defrost is on. Maybe you live in Phoenix and don't care though.

 

I also get what you are saying and appreciate it. I live in WA state. It rains a lot here. It's a trade off. Right now I'm running a single core radiator and it's barely adequate and so even with defrost in the winter I still need fans to cool the engine in heavy traffic anyway....at least until I finally get that 3 core radiator I've always wanted. I'll probably add a Key ON power on manual override switch function. I'm open to ideas about how to get a fan switch on the dash that isn't too bad.