So I have been giving this a lot of thought. My 90 XJ has been running hotter than normal and I think the culprit is the fan relay as the fan doesn't come on.

I can unplug the connector at the fan and probe it with a test light and with the key on or off I get no power.

I can remove the relay and I get power when I probe the terminals I get power on terminal 30.

With the key on or off when I put a jumper wire between number 30 and 87 the electric fan kicks on.

Does this mean the relay is bad?

I would like to hardwire the fan to a switch which I can turn on or off at my leisure. Anyone have a ny writeups for an 87-90 Renix era Cherokee on how to hard wire the fan to a switch?

I have a two prong switch...I have a fuse holder...I have wire...I have terminals and butt connectors...all I need is someone to tell me what wires to tap into and where to connect the wires...

 

What r your ambient temps? If all of the cooling system is in top notch condition, I would think the belt fan alone should keep things cool under most driving conditions this time of year. U do need a efan, just not likely in cool ambient temps.

 

Have you tried swapping the fan relay? The electric fan won't come on until the temp hits a certain point, not sure what that is in the Renix, but it's normal for it to NOT spin unless it's needed for additional cooling.

 

^^^^ and I wonder what the OP means by hotter than normal?

 

I had the same thing happen to me. I have a 1990 2 door XJ and when I would go off-roading or just sit and idle I would run really hot, so I put in a over head switch panel so I could turn on the electric fan whenever I thought Id need it. I believe my water temperature sensor is acting up because sometimes it comes on when its suppose to and sometimes it doesn't. If you need I can take a picture of the relay and my wiring, just ask. Basically, I ran a wire from the low power side of the fan relay, through the fire wall, and then to the switch in the control panel. From there I went from the switch to ground. This in turn makes the relay turn on and gives power to the AUX fan whenever I throw the switch. Check out my build thread at the bottom of the page, I have a few pics up of the control panel.

 

I was in a parade last Saturday and my Cherokee boiled over on the route.. The fan NEVER came on.It was very embarrassing.At speed I normally run about 210...on slow crawls it heats up and the fan doesn't come on.

 

A parade!......that explains it. Everything, not just the efan, MUST be in top notch condition. How old is the fan clutch?......or other cooling system components? Fixing the efan to run automatically as the factory intended is preferable, thus sensing when it is/is not needed. For the most part, thinking that installing a manual fan switch will correct a overheating problem is just a band-aid. When the XJ was new, can u imagine what a 1st time buyer would have said if he saw a manual fan switch that had to be flipped to prevent overheating? Fix it right....no band-aids. If u want to install a manual switch for say high water crossings, that's one thing, but not to compensate for a efan (and/or other cooling system components) that is/are not properly functioning while driving in a parade. Parade driving (slow coolant flow, slow air flow) can be tough on any vehicle. Any/all rad fans gotta be humpin'/thumpin' when driving in a parade.

 

I took the fuel pump relay out, tried starting the vehicle and got a no start situation...as it should. I then took the fan relay and put it in the place of the fuel pump relay and the vehicle started, sooo the fan relay is good...right...? So what I causing my fan to not kick on?

 

If you look on the drivers side of the radiator there is the temperature switch for the fan. Follow the wires and their is a connector. If you jump those two wires it turns the fan on. I've messed with it a couple times. Just tap both wires and when you flip the switch it tricks the system into thinking the coolant is at 218 or whatever the switch normally turns on