At what speed do the fans start when the set temperature is reached?

The fans come on at 60% speed, which reduces the load on the charging system. Fan speed increases with temperature, reaching 100% after a 10°F rise above the set point (e.g., set at 185°F, 100% at 195°F).

How far can the adjusting screw on the Flex-a-lite controller be turned?

The maximum rotation of the adjusting screw is ¾ turn, per the caution note.

How should the AC compressor sensor wire be connected?

Connect only the positive OR negative signal wire to the AC Compressor Sensor — NOT BOTH. See the instructions.

What is the part number for the optional Flex-a-lite manual switch?

The optional Flex-a-lite Manual Switch is Part# 31148. It can be wired for 'Manual OFF (water crossing)' or 'Manual ON' using terminals 1, 2, 3 with ground (switch illumination) and a 12-volt source.

What wire colors are used in the fan controller hookup?

Thick red (battery + through a fuse), thick black (battery −), thin red (12V keyed source), thick purple, thick yellow, + red and − black to the fan, and a green wire toward the AC sensor circuit.

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Flex-a-lite Variable Speed Fan Controller Wiring Diagram & Instructions (99295)

Flex-a-lite variable speed fan controller wiring and installation diagram

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Wiring diagram for a Flex-a-lite variable-speed electric fan controller showing battery, fuse, thermostat and switch connections.

AI caption October 2010 · Photo 939 of 1197

This document is page 2 of a Flex-a-lite variable speed electric fan controller instruction sheet (rev. 11-06-06, document 99295), scanned from a printed installation guide. It explains the Variable Speed Control's operation: when the set 'on' temperature is reached, fans start at 60% speed to reduce charging system load, ramping to 100% over a 10°F rise (e.g., set at 185°F, fans reach 100% by 195°F). A caution note states the adjusting screw's maximum rotation is ¾ turn. The main wiring diagram shows connections between the battery (thick red positive through a FUSE, thick black negative), the controller terminals (2, 3 and 5–11), the fan motor (+ red, − black), a thin red ignition/keyed 12V wire, thick purple and thick yellow wires, a green wire, a thermostat probe, and an AC compressor sensor signal (connect positive OR negative signal wire, not both). It also diagrams two hookup options for the optional Flex-a-lite Manual Switch, Part# 31148: 'Manual OFF (water crossing)' and 'Manual ON', each using terminals 1-2-3 with ground (switch illumination) and a 12-volt source. This is aftermarket fan controller documentation, not vehicle-specific factory wiring.

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Frequently asked questions

At what speed do the fans start when the set temperature is reached?: The fans come on at 60% speed, which reduces the load on the charging system. Fan speed increases with temperature, reaching 100% after a 10°F rise above the set point (e.g., set at 185°F, 100% at 195°F).
How far can the adjusting screw on the Flex-a-lite controller be turned?: The maximum rotation of the adjusting screw is ¾ turn, per the caution note.
How should the AC compressor sensor wire be connected?: Connect only the positive OR negative signal wire to the AC Compressor Sensor — NOT BOTH. See the instructions.
What is the part number for the optional Flex-a-lite manual switch?: The optional Flex-a-lite Manual Switch is Part# 31148. It can be wired for 'Manual OFF (water crossing)' or 'Manual ON' using terminals 1, 2, 3 with ground (switch illumination) and a 12-volt source.
What wire colors are used in the fan controller hookup?: Thick red (battery + through a fuse), thick black (battery −), thin red (12V keyed source), thick purple, thick yellow, + red and − black to the fan, and a green wire toward the AC sensor circuit.