JamesC

iTrader: (5)

For some time I've wanted to convert to dual electric fans, but I didn't want to be inconvenienced by various in-cabin manual switches. My desire was that the fans switched on automatically. The following idea is from AndyZ28 who, members may recall, was one of the first to develop the 1LE brake conversion (more about that can be found on his CD, www.andyz28.com).

How's It Work?

According to Andy, any time a parameter is met, coolant temperature or A/C pressure, the controlling switch grounds the relays turning both fans on. The fact that the switches are "making ground" permits control with very little current flow through the switch(s), as opposed to controlling the relays with the "ign."

Parts Required (I generally bought new, but many of the following parts can be picked up cheaply in a boneyard):

Fans - Stock GM.
Motors – CarQuest 209089.
Motor Wiring Harness/Pigtails – CarQuest S568. Revised p/n 57-4549.
A/C High-Pressure Switch – GM 14089590 (NO, Normally Open).
A/C High-Pressure Switch Harness/Pigtails – GM 12085521 or AC Delco PT131.
A/C Hard Line With an A/C High-Pressure Switch Provision -- As far as I can determine, GM has discontinued the original part, and GM's A/C Line Adapter for Retrofit will not work. (Threads on the valve won't accept the A/C high-pressure switch above). The part, however, wasn't difficult to locate. In two yards I found a half dozen or so.
Two Relays – Painless Fan-Thom 30101. The wiring in the Painless Relay kits is marked for destination which makes running them pretty much foolproof.
Coolant/Thermal Switch - CarQuest TS217 (NO, Normally Open, comes on at 212). This part will fit in the pass side cylinder head.
Miscellaneous - wire (the various gauges are noted below), butt connectors, ring connectors, Posi-Locks, shrink wrap, convoluted plastic tubing, battery side mount, dielectric grease, etc. Good wire strippers and a crimper are helpful.
Mounts for the Relays: I used the stock relay-mounting piece (GM 10020508).

Other Issues:
Andy, in his set-up, uses a light to indicate when the fans switch on. I initially liked the idea but wanted something more stock in appearance. I purchased an Autometer bulb/socket (P/N 3220) and found that after very minor modification to the socket it would twist into the rear of the gauge cluster as if it were stock (find an empty socket and if need be, carefully cut away the plastic of the circuit board). Join one pigtail of the bulb/socket (16 gauge) to a wire going the coolant/thermal switch, and the second pigtail (16 gauge) to the ignition wire which enters the cabin. I copied the font of the "choke," "check engine," and so on in the gauge bezel (Arial narrow 16 in bold face), printed "Fans On", transferred the print to a transparency, and cut a square from the transparency to fit the inside of the bezel. The effect is absolutely stock. That said, in the end, I chose not to go with the light.

JamesC

JamesC

iTrader: (5)

Connections: The relays have four wires each.

From the relays, 1 wire each to the positive terminal of the battery (12 gauge) via the circuit breaker provided in the Painless kit. Both wires go to the battery side mount. See the next to the last pic.

JamesC

iTrader: (5)

From the relays, 1 wire each to the positive fan pigtails (12 gauge). Neg pigtails are grounded (12 gauge). See next pic.

JamesC

iTrader: (5)

I used existing grounds on either side of the radiator.

JamesC

iTrader: (5)

From the relays, 1 wire each to the ignition (18 gauge). I combined these two with a Posi-Lock 3-Way Connector (PLO812—a 14-gauge butt connector would do as well) and then used a 14-guage wire so that only one wire entered the cabin. I terminated with a spade and used an empty ignition slot in the fuse box.

JamesC

iTrader: (5)

From the relays, 1 wire each to the coolant/thermal switch. I combined the two wires in one end of a 14-gauge butt connector, then ran a 14-gauge wire to the coolant/thermal switch. (These first two wires would normally be the relay's ground (18-gauge).

JamesC

iTrader: (5)

From the A/C high-pressure switch pigtail, 1 wire to the coolant/thermal switch (18 gauge). I combined this wire with the 14-gauge wire from the relay as mentioned above, using a 12-10 gauge butt connector, then ran a 12-guage wire to the thermal switch. (You're actually combining three wires: two from the relay—already combined to one--and one from the A/C high-pressure switch). Note the hard line, high-pressure switch, and pigtail. The second wire from the A/C high-pressure switch pigtail is grounded (18 gauge). Note the coolant/thermal switch in the next pic.

JamesC

iTrader: (5)

The second leg of the coolant/thermal switch is grounded (12-gauge).

JamesC

iTrader: (5)

Grounds from high-pressure switch, coolant/thermal switch and battery. Note the circuit breakers and battery side mount.

JamesC

iTrader: (5)

My new 350 HO Deluxe. Note the relays on the driver's side bulkhead. Any advice or suggestions about how to make this set-up better are sincerely invited.

JamesC

Forshock 85TA

What are your temps compared to the belt fan (in the process of doing the conversion myself, sans the AC)

Thanks

JamesC

iTrader: (5)

I don't know exactly. I took a 40-mile highway drive yesterday afternoon. The temp here in Kansas was 98 degrees. With air con blowing, I was only at the first peg of the temp gauge (yes, I know that they're not terribly reliable), which was certainly less than with the belt fan. I saw the real difference waiting in the drive-through at Mac's. In the past, I might have had to cut the air con all together and jump the idle speed up in order to cool the car down to a respectable limit. Not so yesterday. The gauge didn't even hit the 220 mark. So all in all, I'm satisified. Something else I like though it has no real importance is how quiet the electrics are compared to the belt fans and how clean they make the engine bay appear.

JamesC

I H8 WWD

iTrader: (5)

Yeah....ummmm Ima have to read everything very carefully. I have single fan awaiting dual fans....but I want one hooked up to the computer to turn on at 185* and the second fan to be manually controlled......just in case my 180 stat and 185 turn-on fan dont do the job....I can turn the other on. I never want to hit pass 210....

Forshock 85TA

Get an adjustable temp switch. Derale, hayden, they all make one. BTW, 210 isnt bad.

I H8 WWD

iTrader: (5)

I thought it would be.....Kind of a high number for anything else. I just know I dont want to hit high temps.

*84TA

Just used this write up to do my conversion. Kudos to JamesC. Being an old thread, I'm not sure if anyone else will use this, but I just wanted to update the part #'s. Carquest went to a new system. The fan pig tails are now 57-4549, and the thermal switch is 53-13804.

JamesC

iTrader: (5)

Hey, *84,

Thanks for the update. I hope your conversion is as satisfactory as mine.

JamesC

oldred95

I know its an old thread but can you elaborate on this switch? Do you know what its actual application is? I searched GM parts direct and Oreillys and neither were able to bring anything up using that number. It appears to be a 3rd gen condenser fan switch but I'm not sure. I'm needing something normally open that will close around 250 psi for high speed fan operation for the AC.

JamesC

iTrader: (5)

It's been long enough that I don't recall much. I did purchase the switch from my dealership.

JamesC

oldred95

But the intended purpose of the switch is to turn a fan relay on when the AC high side pressure gets too high? Thats what I am after.

JamesC

iTrader: (5)

On my set-up, both fans turn on with the appropriate coolant temperature and/or A/C pressure.

JamesC

oldred95

Do you happen to remember what the pressure on/off was?

JamesC

iTrader: (5)

Sorry, I don't.

JamesC