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Electric fan not turning on

MudfrogK5

NAXJA Forum User
Location
Roanoke VA
90 XJ.. I've been having issues with my temps gettin up around 230, I checked my electric fan and it's not turning on even when at 230. Is there a fuse or something that might need to be replaced? Something else I should look at?
 
It could be the aux fan relay--try swapping with another accessory or starter. There is a fuse as well. It could be a bad coolant temp sensor--does it turn on when you unplug the cts at the t-stat housing(if so, you know it's not a power issue)?
 
It could be the aux fan relay

I just had my relay go out. The fan wouldn't kick on when the A/C was on or when it was getting hot. Pulled the fan relay and it was super hot. Replaced with a new relay and it works like a champ now. Is your fan easy to spin? See if the bearings are still good in it. The fan itself may have crapped out on you too.
 
I just had my relay go out. The fan wouldn't kick on when the A/C was on or when it was getting hot. Pulled the fan relay and it was super hot. Replaced with a new relay and it works like a champ now. Is your fan easy to spin? See if the bearings are still good in it. The fan itself may have crapped out on you too.

The fan does spin freely
 
Down on the radiator, driver side on the tank is the fan switch (brass "plug" in pic below). The harness should run under the air box to a connector. Disconnect it from the harness and use a jumper across the pins on the main harness side. The fan should turn on. If not, then either, you're low on coolant (trapped air in the rad), the switch is bad, or the fan is bad.

Make sure you don't disconnect the fan for this test (connector next to sensor).

JeepEngineBay010.jpg
 
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Then disconnect the fan itself (connector in view in pic above) and apply 12volts to the fan side. If the fan spins, then you've narrowed it to the switch or coolant level.

You could do this test before the coolant switch test. This order doesn't matter.
 
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Adjusted my TPS last night and the fan started working correctly.. dunno why but it seems to be fine. I'm still getting high temps though so lets hope the water pump will fix that.
 
RENIX rigs (90 and below)
Temp switch - on the lower drivers side radiator - feeds the relay to tell the fan when to come on.
Coolant temp sensor (CTS) - feeds info to the copmputer to adjust fuel mixture etc.
Temp sender - rear of drivers side head - for the gauge or light (whichever you have)

Related question on CTS. Since the (90) RENIX CTS that feeds the computer is on the lower block (not the t-stat housing). If you pull that sensor, do you drain the block? or is it isolated...and what size square stock is the block drain plug..?
 
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