When does the ECM ground the coolant fan?

When does the ECM ground the coolant fan?

The ECM grounds the coolant fan circuit when the coolant temperature sensor indicates the temperature is greater than 222° or when the A/C head pressure is greater than 232 psi and the vehicle speed is less than 35 or 40 mph (depending on application). When this circuit is grounded, the fan relay is energized and voltage is applied to the fan.

What are the specifications of a Gm F-body coolant fan?

Derale makes an adjustable relay (Part No. 16759). Available through Jegs (800) 345-4545 for about $42. Adjustable turn-on from 140° to 260°. Adjustable turn-off from 2° to 20° below turn-on temperature. Can be turned on automatically when A/C is engaged. Can be wired to augment factory switch, not replace it.

What’s the fan turn on on a Gm F-body?

Fan turn-on at 176°, off at 166°. Hypertech makes a fan switch (Part No. 4028). Available through Summit Racing (800) 230-3030 for about $45. Replaces factory switch. Fan turn-on at 200°, off at 185°.

Is the secondary fan controlled by the ECM?

On some applications, the secondary fan is controlled by the ECM, A/C pressure switch and a temperature sensor, similar to the primary fan. On other applications, the ECM is bypassed and only a temperature sensor is used. Here is a sampling of products that will modify the factory settings.

Derale makes an adjustable relay (Part No. 16759). Available through Jegs (800) 345-4545 for about $42. Adjustable turn-on from 140° to 260°. Adjustable turn-off from 2° to 20° below turn-on temperature. Can be turned on automatically when A/C is engaged. Can be wired to augment factory switch, not replace it.

The ECM grounds the coolant fan circuit when the coolant temperature sensor indicates the temperature is greater than 222° or when the A/C head pressure is greater than 232 psi and the vehicle speed is less than 35 or 40 mph (depending on application). When this circuit is grounded, the fan relay is energized and voltage is applied to the fan.

Fan turn-on at 176°, off at 166°. Hypertech makes a fan switch (Part No. 4028). Available through Summit Racing (800) 230-3030 for about $45. Replaces factory switch. Fan turn-on at 200°, off at 185°.

On some applications, the secondary fan is controlled by the ECM, A/C pressure switch and a temperature sensor, similar to the primary fan. On other applications, the ECM is bypassed and only a temperature sensor is used. Here is a sampling of products that will modify the factory settings.