A/C fan wiring?

[tekdeus]

A few days ago I noticed that my A/C aux fan was working. Recently on a very hot day, I noticed it was not working.

How can I wire it up so it is on all the time whenever the A/C is on? I find that the performance of my air conditioning is not good enough at idle in slow traffic. My 3.5" downpipe is very close to the firewall and really heats up the dash and venting system, so the A/C isn't as cold.

 

[Who]

First of all does the ac aux fan work? If you give it + / - does it turn on? If it does turn on then you have to know why and when it runs in the first place. If the coolant goes above 212F the fans should turn on. If the head pressure on the compressor goes above 220psi the high pressure switch turns the fans on. My aux fans were not working when I first got my car. I tested the fans and they were good. I grounded the relays and the fans turned on. The problem was low refrigerant pressure in the ac system. The pressure on the high side line never got high enough to ground the the high pressure switch and turn the fans on.
See the horrible image of a flow path on the ac and fan functions. I cant find the original.

 

[CajunKenny]

Brad, I forget if your fan setup is stock or not; but, even if they are aftermarket fans they should turn on when the A/C is on. That is VERY important so you don’t blow/split you’re A/C lines.

Find the A/C control wire under the hood and tap your fan control in to that. On my 87 I tapped into a wire that was right next to the fuse block. On my 91 I tapped into a wire located in front of the battery. I had to remove the battery to access the wire.

I’m at work right now; but, if you need me to, I can post pics of which wires I tapped in to when I get home.

 

[adampecush]

are you still on the stock radiator or upgraded aftermarket?

 

[tekdeus]

It would be great to know how to just ground out the relay that's controlling it, I'm looking at the TSRM and it's not very clear. I'm assuming it is Fan relay #3 but I see no relay in that location on my '87. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AC&P=30

The rad fans are flexilite, and the front aux AC fan is an upgraded single flexilite that looks to be connected to the stock wiring.

 

[tekdeus]

I found the relay and was able to rig it up. A/C seems to work better now!