alternator perhaps?

[caterpillarpie]

When i turn on my aircon, my car just about stalls. When i turn on the stereo it goes fine and then after about 10mins, everything electrical in the car cuts out (lights, indicators) and the stereo resets itself. Ive had it checked and the headdeck is connected fine.

Any light on what the problem is PLEASE!!!!

katie

[toyomoho]

Do you have a very high wattage stereo? Put a real load on the engine such as headlights, heater motor and see what happens. Get a voltmeter and check battery voltage engine off. Should be about 12.8V. Start engine and do the same, should be about 13.9-14.5V if the alternator is charging. The car might have a circuit breaker that is tripping.

The issue with the A/C could be something like the idle up circuit that increases the idle when the A/C is turned on.

[caterpillarpie]

Ok, so I tested the voltage, and no, I dont have a high wattage stereo, 50x4 and currently only 2 front 6inch speakers, so not much, this problem only happens when the head deck is on, when its not on, the car has no problems, cept for air con and I think thats un-related anyway, however, when I idle, I can tell there's somethin not right seein as headlights dim slightly when break pedal is used etc etc, also the voltmetre in the dash moves whenever i hit the breaks,
My multimetre told me this,
Engine of, 12.4 - 12.6
Engine on, 14.2 with nothing on,
It dropped to 13.9 with headlights and break pedal down,

I turned A/C on just to see what happens
and the voltge drops, it goes,
14,13,12,11,10, stall.

Anywyas, HOW can I figure out what the problem is??? does anyone have any ideas???

[retiredat44]

if headlights dim with the brakes lights applied, then you eithe rhave a battery going, or alternaor. But, usually the alternator wil cause the dashlights to come on. Some parts stores will test your eletrical system either free of for a small charge.