Installation Instructions
#31163 Variable Speed Control with Screw-in
Temperature Sensor
FOLLOW THESE INSTRUCTIONS CAREFULLY TO AVOID DAMAGING THE CONTROL UNIT,
FAN MOTORS, AND YOUR VEHICLE! WHEN CRIMPING WIRES, ALWAYS USE A QUALITY
CRIMPING TOOL (DO NOT USE PLIERS).
Important:
Before beginning, be sure that the Variable Speed Control unit (VSC) is mounted close enough to the
temperature sensor so that the wires will reach the control unit. The lead on the sensor is approximately 4 feet.
1. Using threaded adapters if necessary (included), screw the sensor into the desired location using Teflon tape
to seal the threads. Use Flex-a-lite part no. 32082 (1 ½” diameter) or 32084 (1 ¾” diameter) to mount sensor
inline with radiator hose (Preferred location - see Detail A). Alternatively, the sensor can be mounted in the
intake manifold (see Detail B) or cylinder head or block (see Detail C). DO NOT overtighten.
2. Carefully strip the ends of the wires. Fold the wire back on itself to effectively double the thickness (see
Detail D). Using a quality crimping tool, crimp the female connectors provided on the ends. Attach the wires
to terminals 10 & 11 on the VSC (it doesn’t matter which wire goes to which spade, but both wires must be
connected). Make sure the temperature. sensor wires are at least 2-3” away from exhaust manifolds or
other extreme heat sources.
3. Start the vehicle and check for leaks. When the engine has reached desired operating temperature, adjust
the VSC to turn the fan(s) on (see page 2).
Detail A Detail B
Detail C
Detail D
01-11-08 Page 1 of 2 part no. 91163
Initial Start-up and Adjustment Procedure
1. Turn ignition on. After 6 seconds, LED #L4 should light up. If not, check to make sure that
there is 12 Volts at terminal #9 on VSC. The delay is to allow starter to start the vehicle without
the fans drawing any power.
2. With your engine running, engage the A/C. The fans should come on and cycle with the A/C
clutch. LED’s #L1, L3 and L4 should be lit when fans are running. If they do not turn on, verify
that the A/C clutch is engaged and make sure you have a positive signal when the clutch is
engaged at terminal #8 (OR negative signal at terminal on #7 if A/C compressor is triggered by
a negative signal) on the VSC. Shut off A/C and let engine continue to idle, or drive the vehicle
a short distance to bring the engine to operating temperature (monitor the vehicle’s tempera-
ture gauge).
3. Verify that the operating temperature has been reached by feeling the upper radiator hose.
Hot water should be flowing through hose into the radiator. If the fans have not cycled on yet,
slowly adjust the screw on the VSC until the fans cycle on. Turning the screw counterclockwise will keep the engine at a lower temperature, and turning in the opposite direction will keep
the engine at a higher temperature. NOTE: THE TOTAL MOVEMENT OF THE ADJUST-
MENT SCREW IS ABOUT ¾ OF A TURN. TURNING THE SCREW BEYOND THE LIMITS
WILL DAMAGE THE UNIT!
4. Once desired temperature is set, let the engine continue to idle and make sure the fans will
cycle to maintain desired temperature. When fans are running, LED’s #L1 and L4 should be
lit. VERIFY THE DIRECTION OF BLADE ROTATION. IF THE FAN IS MOUNTED TO THE
ENGINE SIDE OF THE RADIATOR, THE FAN SHOULD BE PULLING AIR THROUGH THE
RADIATOR.
The Variable Speed Control has new features!
At the set 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 195°F,
then between 195° and 205° the fan speed will increase from 60% to 100%. So after a 10degree rise from the set point, the fans will be running at 100%.
Turning screw counterclockwise = cooler temp.
Turning screw clockwise = warmer temp.
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 product 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.
Page 2 of 2 01-11-08 part no. 91163
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