HVAC Systems · Electrical Components
Control Transformer
A step-down transformer that converts line voltage (120/240V) to the 24V control voltage used by thermostats, contactors, gas valves, and relays throughout the HVAC system.
Common uses
Supplying 24V control power, isolating the low-voltage circuit
Common symptoms
- Blank thermostat
- No 24V at control board
- Repeated blown low-voltage fuse
Common repairs
- Transformer replacement
- Short-circuit tracing
- Fuse replacement
Related terms
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