cash's90

Where is the fan switch located? It's threaded and screws into the block or one of the heads. It is not the temperature sensor on the right side at the rear of the engine between the plugs. It is not the sensor that is above the water pump under the plenum. Thanks in advance.

WVZR-1

There isn't for a '90. If there's one between cylinders#1 & 3 then it would have been a 'modification' done by someone. '90 fan control is all ECM and AC control.

cash's90

This is the switch I'm trying to locate.
1985-1990 Chevrolet Corvette Auxiliary Fan Switch - AC Delco W0133-2214911

lrj975

that listing is wrong, should say 1985-1989

90 has a square drive plug between cylinder 1 & 3 that could be removed and a Fan Switch added there, then splice into the wiring to the fan relay to turn on fans.

Churchkey

90's may look the same & have an l98 but they have a different operating system than earlier years + they all have 2 fans.
The sender between cyls 6 & 8 is for the temp gauge.
Main coolant fan temp switch is under the T-stat housing, if the AC is not in use the left coolant fan will turn on @ 228 coolant temp. The left side fan will run whenever the AC is in use regardless of coolant temp.
The right side or secondary fan is not an engine coolant fan it only runs when the AC high side pressure exceeds 180#. That pressure switch is located in the liquid line near the fan shroud.
Both fan relays are located on the left side on the fan shroud. Relays always have 12v & are triggered through the ground side VIA the ECU. Suggest connecting both fan relay ground wires together with a jumper wire = both fans will run @ 228 engine temp or when the AC is in use.
Good luck

Churchkey

85 to 91 GM cooling fan switch Four Seasons 35946 Engine
Mounted Cooling Fan Temperature Switch on @ 212*

This switch has 3/8 pipe threads & fits l98 heads. This is a 1 wire grounding switch.