Tech Question on Cooling Fan

Teamoatmealpie · May 7, 2009

Seems like the fan kicks on and off to cool the engine way more frequently then it used to. Any on else experienced this? I asked my mechanic to check the thermostat, and he said its fine, but I am not so sure. I know the 4.0 runs hot, but this seems to be different then how it was in the past. I have owned it since brand new.
Any ideas?
Thanks in advance.
TOP

Avanteone · May 7, 2009

Does the fan only cycle more quickly with your a/c or defrost on?

Any time the defrost is on, it runs the a/c. Any time your a/c comes on, your electric fan cycles. If your a/c system is slighly low on refrigerant, it will cycle much more often and thus your fan will come on more often.

John

FiFo · May 7, 2009

Have you checked the fan clutch?

mojojojo · May 7, 2009

Avanteone said:
Does the fan only cycle more quickly with your a/c or defrost on?

Any time the defrost is on, it runs the a/c. Any time your a/c comes on, your electric fan cycles. If your a/c system is slighly low on refrigerant, it will cycle much more often and thus your fan will come on more often.

John

X's 2 the electric fan is controlled by the Low pressure switch in the AC system.

check yur freon

FiFo · May 8, 2009

Avanteone said:
Does the fan only cycle more quickly with your a/c or defrost on?

Any time the defrost is on, it runs the a/c. Any time your a/c comes on, your electric fan cycles. If your a/c system is slighly low on refrigerant, it will cycle much more often and thus your fan will come on more often.

John

So let’s say I remove the A/C but leave the pump so that I can use it for OBA at a later date. If I use the Defrost what happens?

Avanteone · May 8, 2009

FiFo said:
So let’s say I remove the A/C but leave the pump so that I can use it for OBA at a later date. If I use the Defrost what happens?

Nothing. It won't engage the a/c due to there being no refrigerant in the system and won't run the fan.

josefxj97 · May 8, 2009

i installed a 2-core radiator and a 180 thermostat a few months back. when on the highway it never heats up more than around 150 and in traffic it barely gets to 180. i thought the e-fan broke because it never comes on anymore but i tested everything that makes the e-fan work including the fan itself and everything still works right. that 2-core raditor made a big difference.

josefxj97 · May 8, 2009

i am installing hood vents next month that should cool it down a little more.

FiFo · May 8, 2009

Avanteone said:
Nothing. It won't engage the a/c due to there being no refrigerant in the system and won't run the fan.

There is definitely no refrigerant in my system, since most of the system is missing and I know my E-fan works. I didn't take it out much this winter though, I'll have to pay more attention and see if the E-fan comes on when it is in defrost or just when it's blowing cool air.

Avanteone · May 8, 2009

josefxj97 said:
i installed a 2-core radiator and a 180 thermostat a few months back. when on the highway it never heats up more than around 150 and in traffic it barely gets to 180. i thought the e-fan broke because it never comes on anymore but i tested everything that makes the e-fan work including the fan itself and everything still works right. that 2-core raditor made a big difference.

FYI, you are creating more problems for yourself than you are fixing. The XJ (and MOST modern fuel injected vehicles) NEEDS to run @ 200+ degrees for maximum efficiency. If you're installing a lower than stock temp thermostat (195*), the coolant isn't staying in the radiator long enough for the radiator to do it's job, AND the ECM thinks the engine is not fully warmed up and will add fuel, and your fuel economy will suffer.

Look around in OE tech, where this belongs. This has been covered thousands of times and beat to death.

John

josefxj97 · May 8, 2009

Avanteone said:
FYI, you are creating more problems for yourself than you are fixing. The XJ (and MOST modern fuel injected vehicles) NEEDS to run @ 200+ degrees for maximum efficiency. If you're installing a lower than stock temp thermostat (195*), the coolant isn't staying in the radiator long enough for the radiator to do it's job, AND the ECM thinks the engine is not fully warmed up and will add fuel, and your fuel economy will suffer.

Look around in OE tech, where this belongs. This has been covered thousands of times and beat to death.

John

yea i read all that info way before i did anything. its a rig built for wheeling but is also my DD for right now. i've had it for almost 2 years now and my mileage is still the same as it was when i bought it.
FYI, a bigger radiator didnt make it run different and the temp hardly ever gets hot enough for the thermostat to open, therfore the radiator is always doing its job.

Teamoatmealpie · May 21, 2009

Guys
Thanks I will have it all checked over again. And its cycling quickly with no AC/defrost on. It will turn on for a few seconds (15 secs) then off for 30 secs then on again. This is at idle and slow drive. On highway its not kicking on. And everything is stock on the engine.

Tech Question on Cooling Fan

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