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Fan Relay Testing Procedure

J

junx

NAXJA Forum User
Location
Alexandria, VA
Is there a procedure for testing the fan relay? I've let it run up to 210+ w/the AC on and the aux fan is not kicking on. I thought it was the fan clutch but my fan shreds newspaper like nobodys business.

Sorry, 1997 4.0L XJ
 
with the engine running, unplug the coolant temp sensor, if everything is working like it should then the fan will come on in a few seconds. be aware that this will turn on your check engine light though.
 
Ten High said:
with the engine running, unplug the coolant temp sensor, if everything is working like it should then the fan will come on in a few seconds. be aware that this will turn on your check engine light though.
Click to expand...


Ok, did that. Aux fan never came on - (waited approx 10 seconds) how can i clear this CEL? unplug the battery?
 
junx said:
Ok, did that. Aux fan never came on - (waited approx 10 seconds) how can i clear this CEL? unplug the battery?
Click to expand...

Welp, i replaced the relay and never could get the fan to come on, even direct wiring to the battery and no luck I now have a new one on order.
 
Last edited:
Electric cooling fan 4.0L: With or without A/C
request the electric fan will come on only when the
coolant temperature is at least 106° C (223° F), and
will remain on until the coolant temperature drops to
103° C (217° F) or below. Regardless of coolant temperature,
When air conditioning system pressures
reach 2068.5 +/- 138 kPa (300 +/- 20 psi) the electric
fan will engage and continue to run until the A/C
system pressure drops to 1620.3 kPa (235 psi) minimum,
then the electric fan will shut off.


This is from a 2000 FSM, but a 97 may be the same way.

Eric
 
I have read that this is NOT the case for 97's. I should really just order a 97 FSM...

I attempted hooking up my fan directly to power and it still does not spin - i'm trying a new fan tomorrow.
 
junx said:
I have read that this is NOT the case for 97's. I should really just order a 97 FSM...

I attempted hooking up my fan directly to power and it still does not spin - i'm trying a new fan tomorrow.
Click to expand...

power to one wire, ground to other (DC motor will work either way) and wont spin-- tomorrow will be a good day! :clap:
 
ebishop said:
Electric cooling fan 4.0L: With or without A/C
request the electric fan will come on only when the
coolant temperature is at least 106° C (223° F), and
will remain on until the coolant temperature drops to
103° C (217° F) or below. Regardless of coolant temperature,
When air conditioning system pressures
reach 2068.5 +/- 138 kPa (300 +/- 20 psi) the electric
fan will engage and continue to run until the A/C
system pressure drops to 1620.3 kPa (235 psi) minimum,
then the electric fan will shut off.


This is from a 2000 FSM, but a 97 may be the same way.

Eric
Click to expand...

:wow: they like to run those pressures and temperatures way the hell :eek: up there before they give the heat any relief. Oh, that's right, they WANT them to wear out sooner, so you can buy a new one when the car payments run out, or everthing just burns up.:clap:
 
Step 1

Ok to check the system first check the fan, run 2 leads straight to the battery one ground one positive. Put one in one side of the fan plug and one into the other. If it works move to step 2. If it dosent then your fan is shot.

Step 2 make sure fan is plugged back in and now unplug the coolant sensor from the radiator. Now with the lead that plugs to the sensor in your hand, cross either a short wire or paper clip across the connections. If fan does not run, your power supply to the relay is bad or relay is bad. If it does work your sending unit has gone bad.

easy enough??
 
As a followup - I replaced my elec fan this AM. I let it sit/cool overnight (currently 60 degrees) and started the car with the AC set to recirc - as soon as the car was on, the new electric fan started spinning. For a 97 it seems the fan WILL turn on at relatively low temps.
 
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