Roadrunnr72

Finished rebuilding the engine. Started it, and after the oil pressure came up, it sounded great. No leaks. Got it up to temp, t-stat opening, making sure it was full of coolant.

The electric fan would not come on. Temp was running 210, and I know that the fan won't come on until about 218? or so. I put the heater control in defrost, still no fan, so I then turned it to A/C, the a/c clutch wouldn't come on, and still no e-fan. I bypassed the AC low pressure switch, and the clutch comes on, and still no fan.

Checked the fuses under the hood, checked the relay, swapped it with another I had. The relay doesn't click when removing and replacing. I put power to the hot wire on the fan, and it works, so that tells me the fan and fan ground are good.

Any ideas on the next plan of action?

The radiator has an 18lbs cap, is this supposed to be a 16? I need to replace it anyway, as it leaks fluid instead of going to the overflow tank.

Anyone run into a problem removing the oil fill cap.? I filled the engine with oil, tightened until it clicked, now when I try to open, it makes a louder click, and yes, I am turning it to the left. My brother was here, and he couldn't believe it wouldn't open. Tried turning back toward closing, and the small clicks, then back and just get the loud clicking, with the cap spinning, and not opening.

Thanks.......,RR

CCKen

Go here and read thread 42. It will explain how your AC switches work.

https://www.cherokeeforum.com/f2/gre...e-6558/index3/

You may want to have your Freon pressure checked. It sounds like it's low.

You need a 16 lb cap. Get a Stant.

Those caps can be *********. If you manage to get it off, get a new one from NAPA.

SeriousOffroad

The refrigerant pressure has nothing to do with the Aux Fan during non-A/C use.

With the engine running, remove the connector from the coolant temp. sensor on the water neck. This should cause the fan to come on. If it does not then the fault lies in the relay control wiring.

Check/clean all of the grounds including the PCM grounds.

CCKen

I guess I'm wrong. I thought he had an issue with the fan not running while in AC. He jumpered the fan and it ran. He's not seeing a coolant overtemp (220*F). So why pull the connector off the Engine Coolant Temp Sensor?

SeriousOffroad

Pulling the connector will force the fan on and confirm that the circuit is not at fault.

Roadrunnr72

I found out that I need the freon checked. But was trying make sure the E-fan was working. I thought it was supposed to come on with it set to defrost. I'm going to check out the thread.

The fan is not working at all, unless I jump it. Just wanted to make sure it's going to come on if the temp goes up. I guess the only way to find that out is when the temp gets hot enough.

Thanks.....RR

SeriousOffroad

Pull the connector like I said in my earlier post.

Roadrunnr72

So is the fan supposed to come on with the defrost on? Or just when the A/C high pressure is high enough, or the engine temp is high enough?

I'll go out tomorrow and disconnect the plug and see if the fan comes on then. Thanks....RR

SeriousOffroad

The fan will come on when the operating temp reaches 213 deg.

Disconnecting the connector will tell the PCM that the engine is hot and that Aux. Fan is needed.

If the wiring is good, grounds are good and the relay is good....the fan will come on.

You will get a CEL but it will go away.

If the fan does not come on....well let's just see what happens first.
Fair enough?

Roadrunnr72

Fair enough, thanks....RR

CCKen

Here's a brief statement from the 2000 FSM about the radiator electric fan operation:

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 223° F, and will remain on until the coolant temperature drops to 217° F or below. Regardless of coolant temperature, when air conditioning system pressures reach 300 +/- 20 psi the electric fan will engage and continue to run until the A/C system pressure drops to 235 psi minimum, then the electric fan will shut off.

Pulling the connector off the ECT sensor is a good quick check to see if the overtemp fan circuit is intact but, unfortunately, it does not check the PCM overtemp trip point setting of 223* F.

As far as the fan AC operation goes, jumping the Low Pressure Cycling switch will check the compressor operation (as you know), but to check the fan circuit you will have to jump pins 2 and 4 of the Dual Function AC High Pressure Switch to see if he fan operates.

Refer to the schematic in that link.

Obviously, your Freon system pressure must be up to spec.

Roadrunnr72

Thanks, Ken. I was thinking that the E-fan would come on, at least occasionally. But it only comes on with A@c high pressure or temp high pressure. Getting ready to head out and pop the connector off, just to make sure that the fan is cycling on. Freon will have to wait a few more weeks. It's not warm enough yet, and I have a few other needs. This XJ has a three inch lift and needs new shocks. I think when it was lifted, the shocks were not replaced, and they are at the limits, or close. It needs a new ignition lock cylinder, as this one hangs, and it's hard to turn the key from the off position. Also needs sway bar bushings and links in the front. So right now, I'm looking at close to two hundred dollars in parts. Thanks for all the info......RR

Roadrunnr72

So, I pulled the connector off the t-stat housing, and the fan came on, plugged it in, and fan stopped. Makes me feel better that it's working. Now time for the other things so I can finally drive it.

Thanks......RR

Roadrunnr72

So, I pulled the connector off the t-stat housing, and the fan came on, plugged it in, and fan stopped. Makes me feel better that it's working. Now time for the other things so I can finally drive it.

Thanks......RR

PBRXJ

So does this mean the fan will work when the coolant temp reaches 223 degrees?
I am experiencing this same issue just replaced the temp coolant sensor so I guess it's just not getting hot enough to turn on the fan, this info is very helpful.
Thanks!