24 V transformer keeps blowing / no low voltage

Electrical

AirCompDX - Field Reference for Air Compressor Techs
All HVAC symptoms
1

Shorted thermostat wire

high
CheckOhm each conductor to ground with power off.
FixRepair or re-run thermostat cable; verify no staple damage.
2

Shorted contactor coil

med
CheckCoil resistance near zero; secondary trips protector.
FixReplace contactor.
3

Undersized transformer for accessory load

low
CheckVA total (contactor + zone panel + humidifier + damper motors) vs transformer VA.
FixUpsize to 75 VA or add dedicated transformer.
Safety

Pull the disconnect and lock out before opening HVAC equipment. Discharge dual-run capacitors before handling. Refrigerant recovery and brazing require EPA 608 certification and proper PPE.