The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 55.2-59 Electric Fan to Manuel Fan

burnin oil · 08-02-2020, 08:51 AM

Temporarily run a hot lead from the battery to the relay and hook it to the terminal that the sensor was on. That should kick the relay and start the fans. If that works then you can replace the wire with a manual switch for the fans. This is the low amp side so any old switch should work.

With the switch in the intake manifold it may not be making good contact with anyifreeze. With the motor at or above radiator level it could have an air bubble in the system and the sensor is reading that air space and not coolant temps until the bubble gets purged. Try parking on an angle with the nose uphill once the temps are up for a few minutes and rev the motor up to around 2000 rpm. May get the bubble out.

08-02-2020, 08:51 AM	#4
burnin oil Registered User Join Date: Jan 2013 Location: Eastern TN Posts: 1,921	Re: Electric Fan to Manuel Fan Temporarily run a hot lead from the battery to the relay and hook it to the terminal that the sensor was on. That should kick the relay and start the fans. If that works then you can replace the wire with a manual switch for the fans. This is the low amp side so any old switch should work. With the switch in the intake manifold it may not be making good contact with anyifreeze. With the motor at or above radiator level it could have an air bubble in the system and the sensor is reading that air space and not coolant temps until the bubble gets purged. Try parking on an angle with the nose uphill once the temps are up for a few minutes and rev the motor up to around 2000 rpm. May get the bubble out.