Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[oneof24orless]

After an absence for about 8 yrs I've got another XJ (4.0) 2000 model year.
I'm happy that the electric fan kicks in when it should, but I've also noticed that when the heater/ventilation is on, it will also kick in a every minute or so for a short period of time.
Now I know it'll come on with the air con,  but I'm taking no aircon position selected. It will only stay off (or at least behave like should) when the vent dial is in the 'O' position.
Any suggestions?


Sent from my iPhone using Tapatalk

[The Smiths]

I'd be happy that it's working at all - and just leave it alone

[oneof24orless]

Perhaps, but I'd still like to know why it's doing it....I wonder if the temp sender may be the reason? Either the one for the PCM or the gauge?


Sent from my iPhone using Tapatalk

[Jonny Jeep]

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 6 138 kPa (300 6 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.

I don't know how efficient the cooling is on XJs, but on my TJ I've never seen 106°C on my scan gauge when monitoring temps. Is it possible the rad fins are a bit blocked or damaged, or the viscous fan clutch a little weak so there isn't quite the cooling there should be? Whether or not that's the case I'd say the electric fan is working as designed.

[daggie]

it will on when you have it on de-mist 

[JamesH]

 
Plus what was said above that if it is coming on and off then just leave it to do its thing

[oneof24orless]

Radiator is 5 months old. I understand all of the above however I'm perplexed as to why it will come on when select the ventilation to come on


Sent from my iPhone using Tapatalk

[JamesH]

There are only two positions on the dial where it shouldn't come on

[oneof24orless]

Which are.....


Sent from my iPhone using Tapatalk

[JamesH]

Vent to feet and vent to face from memory, at 1 o'clock and 2 o'clock on the dial I think - I don't have one to check anymore

[oneof24orless]

Even without air con on, correct?


Sent from my iPhone using Tapatalk

[donk498]

The air con will be on unless the dial is in the off position or  feet or face position. If it's windscreen it will be on. Easy way to check is watch the compressor clutch and see if it's engaged when the fan is cycling.

[Jonny Jeep]

If you look what I quoted above from the FSM, the fan will cycle on and off either with the AC pressure, or whether AC is on or off at coolant temp of 106 down to 103 C.

If it stops cycling when AC is off it must be related to AC system pressure.

If the AC is off and it still cycles it must be temp related. A scangauge or bluetooth adapter and mobile phone app could be used to see if it cycles with temps specified. I think if the temp sensor had failed, the fan wouldn't work at all with temp as they normally go open circuit if they fail which the computer would see as running cold. If it is cycling with temp there must be something making the engine run slightly hotter than normal. The viscous clutch can be tested following a process described in the FSM.