Q: Aircon makes car battery flat

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My son bought this car second hand $500, whenever he runs the aircon when he's driving, after he turns the car off the car won't start again. What do you think the problem could be?
My car has an automatic transmission.

Hi there. From the description you have provided, the alternator may not be keeping up with additional load of the air conditioning system. This could be the result of, a loose/worn drive belt or a faulty voltage regulator which is integral of the alternator. Proper diagnoses should be performed to avoid unnecessary repairs. I recommend having your vehicle’s a/c causes the battery to die be diagnosed and repaired by a certified technician, such as one from YourMechanic.

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