Replacing Fan Switch

[mattyd7]

Today my radiator fan stopped coming on. Since it has been working and nothing has changed I doubt there is air in the cooling system suddenly. The top and bottom radiator hoses feel the same temp. I disconnected the fan switch and shorted the connector and the fan came on, so fan still works and that circuit is fine. Checked resistance of the fan switch plug and it was an open circuit with engine very hot. So appears that the fan switch is bad.

So, to change the switch, must I drain the coolant? Is it open to the inside of the radiator behind there and actually getting the temp of the coolant? None of my repair manuals actually tell you the steps to change the switch.

[124JOE]

yes drain the coolant

[Rambo]

Make sure when you remove the switch you dont bend the housing. Most often a sharp jolt is better then pressure to remove the switch. Make sure you use the copper washer that was on the old switch.

[spider2081]

I have changed a few without draining the system. I add coolant to the overflow bottle making sure it is well above the spike in the tank. I have done it after the car has set for a day. this makes sure the thermostat is closed. I make sure the radiator cap is on all the way. I believe this procedure minimizes the amount of air that can enter the system. Sort of like putting your finger over the end of a straw. The remove the old switch and be ready to quickly install the new switch. Very little coolant is lost.

[mattyd7]

I have changed a few without draining the system. I add coolant to the overflow bottle making sure it is well above the spike in the tank. I have done it after the car has set for a day. this makes sure the thermostat is closed. I make sure the radiator cap is on all the way. I believe this procedure minimizes the amount of air that can enter the system. Sort of like putting your finger over the end of a straw. The remove the old switch and be ready to quickly install the new switch. Very little coolant is lost.

After they said that there is coolant behind the opening, I was thinking to myself: "I wonder how quickly I could pull the old one and put the new one in without losing much coolant?".

Thanks everyone.