mercsimon

Hey again, so it's probably pretty obvious that this is my first Jeep Cherokee and I'm probably gonna post a lot of really dumb seeming questions.

tl;dr on the bottom of the post.

OK, I have a 1996 Jeep Cherokee Sport 4.0l 6cyl 4wd 4 Door. So when I bought it I noticed that when I turned on the A/C the voltage meter would drop from just under 14 volts to about 11-12 volts. I had the battery and alternator tested at Auto Zone. They said the battery was good and the alternator was bad. So before ripping out my alternator I cleaned my battery terminals and connectors and had it re-tested. They said everything was ok. But then I turned the A/C back on and the voltage dropped again. So I changed the alternator and it's still pretty much the same. The voltage doesn't always drop as low but it still drops.
Also, I tested the battery with a multimeter and with the Jeep off and the battery gives a solid 13.7 volts

Is this normal? Or is there something obvious I'm missing?

Thanks guys!

tl;dr

A/C making voltage drop. Replace alternator, check battery (13.7 volts while Jeep is off) No change in voltage drop with A/C on.

Jeep Driver

Do not trust the stock volt meter.

Mine does the same, however, my electronic volt meter tells a different story.

cruiser54

Yep. Pretty normal.

cliffy

I had the same issue, I cleaned the ground connection that is on the outside of the compressor housing. It is exposed to moisture and had some corrosion on it. Now when the AC or defroster is on no change on the meter in the dash.

ehall

When you turn on the AC you also turn on the blower motor. Two fan motors drawing amps: the condenser fan, and the cabin blower fan. Its a big draw. The other part of the problem is that the voltage gauge wiring is on a shared circuit, so it ends up exaggerating the drop. You can measure the actual voltage at the battery to see the true voltage, and if it really bothers you then can change the wiring on the gauge to get a better reading

cruiser54

Cliffy, you got my attention with that one.....

You guys ever see this?

http://www.jeepforum.com/forum/f11/r...ge-fix-684375/

cliffy

Yes, It is a nice write up there was a similar thread to this one some time ago and you shared it then too. If my problems return I will look into doing it then, thanks for the reminder.

cruiser54

Now I wanna do the AC compressor ground using OxGard!!

wyrick

Wow, didn't think of that. I'm researching as mine does the same thing. I thought it could be tied to the blower motor or resistor not functioning properly as the higher the setting on the blower the more the voltage drop.
I have a question though, last winter with my blower motor at 75% it would occasionally cut out for a second. Is that familiar to anyone?