Wiring twin cooling fans

Lee H · May 10, 2014

My car has no aircon but due to the extra heat likely from the 3SGTE I want to fit a second fan in the empty space for the aircon fan up front.

Have collected another pair of fans and have noticed they are different. Aircon fan has more blades and rotates in the opposite direction to the normal rad fan. They are the same size so I am thinking it best to fit the two normal fans I have so they match.

Just not sure one the wiring. If I bridge the second fan onto the first fans wiring am I likely to blow the relay or cause the fans to run at half speed? I also have the connector for the aircon fan but I assume this fan normally only works with the aircon switched on and doesn't have anything to do with coolant temps etc?

Anyone offer any advice?

Cheers

Lee

KseriesPower · May 12, 2014

I will be doing something similar as well in this area.
Ignore the Blue X's

The radiator fan and condensor fan are both in same shroud behind the radiator.

A simple wiring change could make them both operate at the same time as radiator FANS. Change polarity to change directions.

Wiring them in parrallel will give them both 12v or more for full speed and wiring them in series will cause a voltage drop causing lower speed. I dont know if they operate at different speeds from the factory (it appears they do). I would wire them in parrallel because im not sure if those fan motors are designed to run less than 12v.

I will post more advice later... gotta go to work

KseriesPower · May 12, 2014

Heres what I would do... Remove Fan Relay #3 and Jump the white and Blue/Black wire. Then, cut the Black wire coming off of Fan Relay 2. Disconnect the AC pressure switch just to be safe.

This gives both fans the same wires and power through the proper fuses. When the ECU calls for the fans to run it will take the blue wire to ground and close FAN1 relay for the radiator fan and close FAN2 relay for the "condensor fan".

This would only be 1 speed operation (high)

dblotii · May 12, 2014

I was having a bit of trouble understnding the fan operating scheme when I looked int to this a while ago. Is the factory strategy that fan# 2 only comes on if the A/C compressor is on?

Dave

KseriesPower · May 12, 2014

when the ecu brings only the ac cond fan signal to ground the Con fan and radiator run in series (low speed).

when only wanting Rad fan to run, it runs by itself.

when ecu brings both to ground they run in parrallel (high speed)

ac pressure switch does the same thing as ecu RAD fan signal

Cap Weir · May 12, 2014

There are TWO stages of Fan.. Series ( Stage 0ne ) and Parallel, (Stage 2..)

They are both called by the Engine ECU, depending upon A/C and Engine Temp..

Do not reverse the Rotation of the Fans.. the Blades are designed to rotate one direction only.. By rotating it Opposite ( Unless Designed to do So ) it will not pump as much air..

Bi-Directional Fans move less air than Directional Fans..

Cap

KseriesPower · May 12, 2014

I didnt even think of the direction of the blades... DUH lol

Wiring twin cooling fans

Top Contributors this Month

Recommended Communities