What fuse size does the Hayden thermostat wiring diagram call for?

The diagram shows a 20 amp fuse in the circuit feeding the switch (ignition side of switch).

How are the manual switch and thermostat connected in this Hayden fan wiring diagram?

Per the printed note, the manual switch and thermostat are shown wired in parallel for independent operation, joined with butt connectors.

Where should the manual fan switch be mounted according to the diagram?

The diagram labels the switch location as 'mount under dash.'

What part number and revision is this Hayden instruction sheet?

It is P 12623-IS (Rev. 3/00); the header also shows SS 12623IS dated 08/21/97 from Dayco Products—Eaglemotive.

What do the hand-drawn red and blue lines show?

They show the uploader's modification adding a relay: red lines route power from the battery through the relay to the fan circuit, and blue lines connect the switched/fused circuit to the relay.

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Hayden Electric Fan Thermostat Wiring Diagram P 12623-IS with Relay Mod

Annotated Hayden electric fan wiring diagram with red and blue wire overlays

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Wiring diagram for an electric cooling fan with annotated red and blue wire routing to relay, battery and switch.

AI caption August 2004 · Photo 312 of 434

This is a scanned Hayden Automotive instruction sheet (P 12623-IS, Rev. 3/00; earlier revision SS 12623IS dated 08/21/97, Dayco Products—Eaglemotive) showing a thermostat wiring diagram for an aftermarket electric cooling fan installation. The printed diagram shows an electric fan unit connected to ground and to a thermostat, with a manual switch (marked "mount under dash") wired in parallel with the thermostat for independent operation, joined with butt connectors. Power runs through a 20 amp fuse to the ignition side of the switch. Over the printed diagram, the uploader has drawn colored lines in red and blue marker showing a modified hookup: red wiring runs from the battery (hand-labeled box) through a relay (hand-labeled box) to a connector block and up to the fan circuit, while blue wiring connects the switch/fused circuit to the relay trigger side. The scan documents both the manufacturer's stock wiring scheme (thermostat plus manual override switch in parallel) and the owner's relay-based modification to carry fan current from the battery instead of directly through the switch. A camera date stamp reads AUG 18 2004.

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Frequently asked questions

What fuse size does the Hayden thermostat wiring diagram call for?: The diagram shows a 20 amp fuse in the circuit feeding the switch (ignition side of switch).
How are the manual switch and thermostat connected in this Hayden fan wiring diagram?: Per the printed note, the manual switch and thermostat are shown wired in parallel for independent operation, joined with butt connectors.
Where should the manual fan switch be mounted according to the diagram?: The diagram labels the switch location as 'mount under dash.'
What part number and revision is this Hayden instruction sheet?: It is P 12623-IS (Rev. 3/00); the header also shows SS 12623IS dated 08/21/97 from Dayco Products—Eaglemotive.
What do the hand-drawn red and blue lines show?: They show the uploader's modification adding a relay: red lines route power from the battery through the relay to the fan circuit, and blue lines connect the switched/fused circuit to the relay.