Adding The Intercooler Fans on a GMC Syclone and Typhoon

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Adding fans to the intercooler on a GMC Syclone or Typhoon can increase vital cooling capacity, especially at lower speeds, or on hot days.

The stock lower heat exchanger will accept up to 2 fans on the back, and definitely increase cooling

Image 6979 from Adding the Intercooler Fans on a GMC Syclone and Typhoon

Jack up the Front of The Truck


Jack up the front of the truck and place it on jack stands.

Make sure the parking brake is engaged, trans is in park, place wheel chocks behind the rear wheels, and everything is safe!

Remove the Lower Charge Cooler Heat Exchanger


Drain the Intercooler.

The drain is visible from the front of the truck. Unscrew it and drain the fluid into a pan.


Remove the 4 17mm bolts on each side of the lower intercooler heat exchanger.


Disconnect the water lines from the lower intercooler heat exchanger.

They are held on using hose clamps. Typically these have an 8mm screw head.


Disconnect the single slide on connector for the coolant level sensor.


Disconnect the intercooler pump wire connector.

Modify the Heat Exchanger Housing


Cut the intercooler housing to clear space for the fans.

The 6.5" puller fan housings are a little larger then the space available.

Draw the shape of the cuts you'll need to make to clear the fans and cut them using a cut-off wheel or dremel.


Finish any cuts you made in the housing by painting them.

Image 6975 from Adding the Intercooler Fans on a GMC Syclone and Typhoon

Attach the fans to the heat exchanger


Place the fans flush against the back of the heat exchanger and attach them using the mounting straps.

The straps push directly through the corrugated pleats in the heat exchanger.


On the other side, place the foam pad and retaining cap.

There's no need to apply extreme force here, just enough to keep the fan in place and keep it from vibrating.

Wire For Power!

There are a ton of options here, ranging from simple to custom and complicated. You could have the fans automatically engaged at certain temperatures, when the intercooler pump is engaged, by the flip of a switch, or at all times the ignition is on.

I chose to use an ignition source with a manual switch I can use to turn them off.

You'll want to use a fuse and a relay for the fans to keep things safe and usable.

Plan out your wiring ahead of time and get it done!

Make sure you create safe, long-lasting, future-proof wiring. Invest in a good soldering iron and buy some heat shrink tubing!

Each 6.5" Spal fan pulls 6.5 Amps


Before we get started, disconnect the battery!


Wire the fans to a switching relay.

Relays allow you to use low power wires and switches to power high power devices. These fans can use a lot of power and the existing wires probably can't carry enough to handle them.

So we'll use an existing switched power source to flip the relay on, which will run power directly from a high power source to the fans.

So let's break down the Bosch Style Relays work.

  • 87 (OUTPUT)
  • 30/51 (INPUT)
  • 85 (GROUND) for the trigger
  • 86 (TRIGGER)

When 85 and 86 have power flowing through them, the relay will connect 87 and 30/51

So here's how we wired our fans:

  • 87 positive wire going to the fans
  • 30/51 fused positive to the battery.
  • 85 grounds to body (we ran it into the cab so we could use our switch)
  • 86 positive wire on the intercooler pump.

This will power the fans any time the intercooler pump is powered and our switch is on.

If either the pump or the switch is off, the fans will not turn on.


Install an inline fuse on the power wire that connects to the battery.


Ground the black wires from the fans to the body or frame.

We chose to run the ground to one of the holes on the bottom of the radiator support just above the intercooler.


Optionally add a manual switch if you desire.

In my case, I added a switch between the relay's 85 terminal and ground.


Test the fans.

Re-install the Intercooler


Re-connect the intercooler water hoses.


Slide the intercooler back into place and re-install the 4 bolts that hold it in place.


Triple check that your wires are run in a safe way. Make sure they avoid as much moisture and heat as possible.

If needed, zip tie them in place to keep them from moving around.


Refill the intercooler with water and anti-freeze as needed.

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