manual radiator fan switch
Adding a manual radiator fan switch to 1989 Lotus Esprit 2.2L Turbo
Darryl Harrison 6/4/20

After refurbishing the water-pump, coolant flush & fitting new hose everywhere the temperature gauge is frequently in the red. Although this seems to be ‘normal’ for my Esprit I find it very unsettling. I have been keen to fit a manual switch, that I can activate when in slow traffic & prevent from sitting in the red while I nervously watch it.

I have re-purposed the Rear Heated Screen (RHS) switch for this which has worked really well (never use it). The switch is illuminated & on the dashboard which is all too handy, no wires to pass through! Instead of activating the relay for RHS, I rewired it to activate the Radiator Cooling Fan relay.

Removed Relay ‘C’ Rear Heated Screen Connect from: Relay ‘C’ WK white wire, + side of the coil (pin 86 on my car) Connect to: Relay ‘E’ BO black/orange wire, + side if the coil (pin 85 on my car) -I tapped into the same circuit connecting to a diode, an easy point to access with a spade terminal.

I made a cable with spade terminals & plugged it in.

1 Relay ‘C’ WK white wire, + side of the coil (pin 86 on my car)

2 Diode connected to Relay ‘E’ BO black/orange wire, + side if the coil (pin 85 on my car)

3 Plug the BO wire from the Relay to the Diode, into my piggy back cable.