OEM Carrier Transformer 40VA 120V to 24V for Model C50A603564

This is the factory-specified OEM replacement transformer (part# HT01BD702) for the Carrier C50A603564 commercial rooftop unit. The transformer steps down 120V line voltage to the 24V signal required by your thermostat, control board, contactor coil, and all low-voltage control components. When the transformer fails, the entire control circuit goes dead — the thermostat loses power, the system stops responding entirely, and no heating or cooling function can be initiated. A failed transformer is often mistaken for a thermostat or control board problem, making correct diagnosis critical before replacement.

• Specs: 40VA rating | Primary: 120VAC | Secondary: 24VAC | OEM part number HT01BD702 | Factory-matched output for full control circuit reliability
• OEM vs Generic: OEM transformers are wound and tested to exact Carrier factory tolerances, ensuring stable 24V output under full load. Generic units frequently underperform at rated VA, causing nuisance lockouts, contactor chatter, and premature control board failure.
• Install Difficulty: 2/5 — Disconnect power at the breaker and verify zero voltage with a multimeter before proceeding. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label all low-voltage wiring before disconnecting from old transformer terminals.
• Warranty: 1-year OEM factory warranty against defects. In-stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier C50A603564 packaged commercial rooftop unit. Always verify primary and secondary voltage ratings on your unit's data plate match 120V/24V 40VA before ordering. Need help confirming fitment? Our HVAC parts specialists verify compatibility before you buy — no guesswork.