Dewey
NAXJA Forum User
- Location
- La Verne, CA
When I turn on my A/C full blast, my volt meter drops almost to the red.
Does this mean I need a new alternator?
Does this mean I need a new alternator?
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voltage drop
- Thread starter Dewey
- Start date
Jeep XJ_YJ
NAXJA Forum User
- Location
- EAST COAST
clean and check your cables/posts first
cherokee chuck
NAXJA Forum User
- Location
- freeland,wa usa
2x then check your belt, when the A/C kicks in it increases the load on the belt.Jeep XJ_YJ said:
Matthew Currie
NAXJA Member #760
- Location
- Vermont, land of big clay
Depending on year, it can also be the voltmeter itself. Try putting the heat on, no AC, and turn fan to max. If you see a big voltage drop, it's lying. If it drops much more with AC than with heat, then check the belt tension.
5-90
NAXJA Forum User
- Location
- Hammerspace
I've said it before, and I'll say it agan:
Always verify suspect IP voltmeter readings with a decent DMM!
The thing is a notorious liar.
Possible causes:
The first is highly likely. #2 and #4 are somewhat likely, but I'd check for #4 first (check and clean all mains connections to/from the battery, make sure the stud nut on the back of the alternator is tight, &c.) Those three can be checked gratis - total cost to you would be a half-hour's time. And, if you turn out to need a belt, replacing the alternator won't fix it (because you haven't repaired the problem itself.)
Always verify suspect IP voltmeter readings with a decent DMM!
The thing is a notorious liar.
Possible causes:
- IP Voltmeter has lost calibration
- Belt is slipping slightly, more with aircon switched on
- Alternator is beginning to fail in some way
- Loose/dirty/corroded connection (power or ground) getting started - noticed under load
The first is highly likely. #2 and #4 are somewhat likely, but I'd check for #4 first (check and clean all mains connections to/from the battery, make sure the stud nut on the back of the alternator is tight, &c.) Those three can be checked gratis - total cost to you would be a half-hour's time. And, if you turn out to need a belt, replacing the alternator won't fix it (because you haven't repaired the problem itself.)
