OEM Carrier 40VA Control Transformer HT01BD702 for Model C50A802064

This is the factory OEM replacement transformer (part number HT01BD702) for the Carrier C50A802064 packaged unit. The transformer steps down 120V line voltage to the 24V signal voltage that powers your thermostat, control board, and all low-voltage safety circuits. When this transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system won't respond to any call for heating or cooling, and no fault codes will display because the board itself has no power. It's one of the most commonly overlooked causes of a completely unresponsive HVAC system.

• Specs: 40VA rating | Primary: 120V | Secondary: 24V | Class 2 transformer | Direct OEM replacement for part number HT01BD702
• OEM vs Generic: This factory OEM transformer is wound to exact VA and voltage specifications for the C50A802064 control circuit. Undersized or off-tolerance generic transformers can overheat, trip thermal cutoffs, or fail to hold 24V under full control-circuit load — causing intermittent lockouts and premature board failure.
• Install difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Verify 0V at primary terminals before disconnecting leads. Note wire colors and terminal positions before removal.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our climate-controlled warehouse.

Compatibility: Designed for the Carrier C50A802064 commercial packaged unit. Confirm your existing transformer's VA rating and primary/secondary voltages against your unit's wiring diagram before ordering. If your thermostat is completely unresponsive and you've ruled out a blown fuse, this transformer is the next component to test with a multimeter. Questions about fitment? Our parts specialists confirm compatibility before every order — reach out before you buy.