Voltage drop when AC on but no battery dash light

Kags1969 · Post by **Kags1969** » 21 May 2019, 09:50

I purchased a 2003 V40 for my sister and am trying to get it to a good spot where she can drive it worry free for a while. Here is the issue that I am noticing.

Using a ScanGauge2 to monitor:

~13.7 on startup drops to 12.7-13.0 during AM commute in (typically no ac)
On commute home (low rpm) 12.7 is normal unless I run the AC at which point it will drop to 11.8-12.0
I can shut off the AC and the voltage will come up to 12.2-12.4 (at idle - low rpm commute speeds)

Not sure if this is a voltage regulator issue or an alternator issue. Any sage advise?

Post by **RickHaleParker** » 21 May 2019, 10:05

Before you start throwing money and parts at it. Clean the battery terminals and the electrical connections to the alternator. Inspect the cables to both for damage. Voltage drops under load can be something that simple.

Kags1969 · Post by **Kags1969** » 21 May 2019, 10:30

Will do. Thanks, Chris