ac robbing engine of power

Hi, 97 4.0l xj converted to electric fan cooled 12 months ago, when either my oem ac fan comes in or my electric cooling fan comes on it robs my jeep of power meaning jeep struggles to pull my small caravan when either fan comes on, new battery 12months ago , charges just under 14v at motorway speeds cant figure out why this is happening , when fan/fans go off power returns it just wont pull when either fan is on ! anybody got any ideas , Jeff

So you can't get the motor to rev up when the electric fans are on??? 14 sounds just about right....maybe you need a higher output alternator?? What was the aux fan that you added, another stock jeep one?? more info would help.

The power to turn the fan needs to come from somewhere, just because it is not attached to the motor dosn't mean it does not take the motor's power to turn it. The energy required to spin the alternator becomes greater when it must make more electrical power.

How does it sound about right with no power when i put ac on!! the auxillary fan i added was a 13" 25amp .

Your 4.0 is seen better days...

It's stroker time.

Nick

terrierman said:

meaning jeep struggles to pull my small caravan

Click to expand...

that there is your problem... =) upgrade your alternator, get one from a dodge v8.... i dont have a part number, but for your late model types it requires only slight grinding... now would be a good time to upgrade your main battery cables, ground straps... if i had a late model. i'd mount that dodge alternator where your a/c bracket is.