Fan 280 Installation Instructions

Free installaltion instruction for Chevy GMC Monster Fan save fuel

Monster Fan 280 Installation Instructions Fits 1992-1999 GM
Full-Size Trucks/SUV with 34" radiator


1. Remove plastic radiator cover, and top half of fan shroud.280_1instal.jpg


2. Remove fan and clutch assembly. If clutch is mounted to pulley with four bolts, remove nuts, remove clutch/fan assembly and replace nuts. Newer vehicles may have the clutch mounted by a large single nut. It may be possible to remove this clutch by fitting a large wrench to the nut. Put a rag over the fan to keep from being cut. Hold the fan in
place and pull the wrench in the direction of rotation, it may help to give the end of the wrench a sharp strike from a soft-blow hammer to break the nut free without the pulley slipping.


3. Remove the lower shroud.


4. Determine if you have a 17" tall or 19" tall radiator, measure the height of the core/ fin area. Also make sure the radiator is a minimum of 32" or greater in length of core/fin area.




1. Select the type of brackets needed for your vehicle.


2. Loosely assemble the correct top bracket to the top of the shroud, the 17" brackets are 2 pieces, the 19" bracket is a single piece.


3. Temporarily mount the fan using the top bracket only. Adjust the bracket so the fan is sealed to the core.


4. The bottom brackets will need to be custom mounted due to the number of variations in GM shroud mounting points from 92-99. Measure the thickness of the radiator core. If it is less than 1.5" then use the 1 core brackets, if greater than 1.5" use the 2 core brackets. Loosely mount the bracket to the lower tray, using the same mounting points as the OEM shroud. Compress the seal of the fan against the core. With a marking
pen, mark where to drill a 1/4" hole for mounting the brackets to the shroud.


5. Remove the fan unit and drill the 1/4" hole for the bottom bracket, and mount the bracket.




6. The VSC fits on the top flat corner of the shroud. Mount the control on the side closest to the battery. Mark the location for the holes then drill 2 x1 /8" holes
for mounting the control onto the shroud. On the side of the VSC with the power input/output you will need to drill a 1/4" or two 1 /8" holes to pass power wires through for the fans.


7. Wire the red and black 14 GA wire to the fan motor furthest from the control. Use a butt connector to wire the red 14 GA wire to the red wire on the motor, then wire the black 14 GA wire to the black motor wire. String the 14 GA wire over to the other motor wire leads and trim the length.


8. Crimp blue bullet style connectors on the ends of the wires. Insert the bullet connectors in the double end of the 2 to1 bullet connector. Place the positive leads in the same connector. The red wire out of the motors is +/positive, black wire is -/negative.


9. Feed the heavy 10 GA wire from the control side into the fan. Now crimp the bare connector onto the 10 GA wire, and insert into connector.


10. Wrap the connections with electrical tape to seal the connections.


11. Mount the fan into place and tighten brackets, adjust so the seal is contacting the core and compressing the seal at least 50%.




1. The red 10 GA wire that is attached280_2instal.jpgto the red motor wires


connects to terminal # 3. The black 10 GA wire attached to the black motor wire connects to terminal #2.


2. Use 10 GA wire and run power directly from the battery to the
VSC. In line with the + battery terminal, place the in-line fuse
Trim the wire to length and attach the yellow female connectors to the VSC.


3. Attach the negative battery lead to terminal # 1. The positive battery
lead should pass through the fuse holder and attach to the VSC at terminal #4.


4. Locate the inlet hose to the radiator from the engine. Take the temperature probe with black cap, remove the cap and insert the probe
into the core cooling fins near the inlet on the radiator tank.
(See DIAGRAM A) Gently push the probe inwards, to move the fins apart. Push the probe through, with 1/2 - 3/4" out the front of the core. Place the vinyl cap on the end of the sensor to prevent the probe from backing out. Trim the two leads to length and crimp red female terminals on the wires and plug into terminals 10 and 11. It does not matter which wires go to either 10 or 11, but both wires must be connected.


5. FOR IGNITION CONTROLLED ACTIVATION locate a + wire or fuse terminal that is “hot” when the ignition is turned on, and off (no + signal), when the ignition is turned off. Or use one of the fuse taps to tap into the fuse and run the 18 GA red wire to the VSC. Attach this lead to terminal #9.


6. Locate the two wires that go into the a/c compressor, and determine which wire activates the clutch compressor when the AC is turned on, this is your signal wire. If the signal wire sends a positive signal, put a splice tap on the positive signal wire with the green wire running back to the VSC, and connect to terminal #8. If the signal wire is negative, then connect to terminal #7. Do not connect both wires to VSC. Only one wire is used to
signal the VSC.


7. FOR MANUAL ACTIVATION use a manual switch (Flex-a-lite #31148) to send a ground/negative - signal to terminal #6. This will turn fans to Full On.


8. To ‘Over-ride’ the VSC and turn the fans off, regardless of engine temp. or AC operation, use a manual switch (Flex-alite part # 31148) to send a ground/negative signal to terminal #5. (Commonly used for water crossings)


9. Check all of your connections and secure wires with the zip-ties. With the ignition turned off, insert the 40amp fuse into the holder and wait 30 seconds before proceeding.


10. Turn the ignition on. 5-6 seconds after turning on the ignition, LED #4 should turn on. If not, check to make sure you have a positive signal at terminal #9. Then check for minimum of 10 V across terminals #1 & 4. With the LED on at #4, the control is active. The 5-6 second delay is to allow for the starter to start the car without the fans drawing
power away from the starter.


11. Start the vehicle. Then turn on the AC. Verify that the AC compressor clutch engages, and that the fans turn on, you should see LED’s #1,3,4 on. If not, check for the correct signal at terminal # 7 or 8. AC runs fans at 60% RPM


12. Turn off the AC and allow the vehicle to continue to idle. Watch the engine coolant temperature on the dash. When the vehicle gets up to temperature, check to see if the engine thermostat has opened by feeling the inlet hose to see if it is warm/hot. The temp. gauge may read the coolant temp in the block not the radiator. The block may be at operating temp but the radiator is cold. When you are sure the coolant is flowing through the radiator, and the temp gauge
is rising, adjust the thermostat setting on the VSC until the fans come on. After running for a while, the fans should cycle off and on to maintain temperature.


13. When you turn the vehicle off, the VSC will stay active for 30 seconds if the coolant temperature is above the set temperature.

The Variable Speed Control has new features.
When you set the on Temperature, the fans will come on at 60%; this reduces the load on your charging system. If the temperature rises, the fan speed will increase. If your set temperature is 185 degrees Fahrenheit, then between 185 and 195 the fan speed will increase from 60% to 100%. So after a 10-degree rise from the set point, the fans will be running at 100%.








The Flex-a-lite Limited Warranty
Flex-a-lite Consolidated, 7213-45th St. Ct. E., Fife, WA 98424, Telephone No. 253-922-2700, warrants to the original purchasing user, that all Flex-a-lite products to be free of defects in material and
workmanship for a period of 365 days (1 year) from date of purchase. Flex-a-lite products failing within 365 days (1 year) from date of purchase may be returned to the factory through the point of
purchase, transportation charges prepaid. If, on inspection, cause of failure is determined to be defective material or workmanship and not by misuse, accidental or improper installation, Flex-a-lite will
replace the fan free of charge, transportation prepaid. Flex-a-lite will not be liable for incidental, progressive or consequential damages. Some states do not allow the exclusion or limitation of
incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty gives you specific legal rights and you may have other rights, which vary from state to state.
The Flex-a-lite warranty is in compliance with the Magnuson-Moss Warranty Act of 1975.
rev. 10-06-05 part no. 99790 Page 1 of 2