I have a 2003 Ford Focus SE with 108,000 miles. I recently change my alternator and now when I turn on the A/C or defroster, the car dies. The fan works fine when just running the fan. Also when I run out of coolant, the alternator warning light comes on, the engine starts to overheat and the car dies.
What needs repairing?
"...when I run out of coolant...", I presume your talking about AC refrigerant. That being the case, your AC compressor is broke (locked up) and when you turn it on, the small engine is stopped by the clutch on the compressor engaging.
Could be other things and not 100% confident I'm reading your question accurately.
Check the alternator by load test that.
When you put load on your vehicle, it shuts off and it tells me that either the alternator or the battery is not working properly.
