OEM Carrier 40VA Control Transformer 120V/24V for Model PY3GNA024040AA

This is the factory OEM replacement control transformer (part number HT01BD209) for the Carrier PY3GNA024040AA air handler. The transformer steps down 120V line voltage to the 24V AC signal that powers your thermostat, control board, and all low-voltage switching throughout the system. When this transformer fails, the entire control circuit goes dark — no thermostat response, no contactor pull-in, and no system operation of any kind. A failed transformer is often misdiagnosed as a bad thermostat or control board, making correct diagnosis and a quality OEM replacement essential.

• Specs: 40VA rating | 120V primary / 24V secondary | Class 2 control transformer | Factory-matched OEM tolerances | OEM Part Number: HT01BD209
• OEM vs Generic: OEM transformers are wound and potted to Carrier's exact specifications, ensuring stable 24V output under full load. Generic units frequently underperform at rated VA, causing nuisance tripping of the control fuse or erratic thermostat behavior.
• Install Difficulty: 2/5 — Disconnect all power before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output post-install), wire nuts or spade connectors. Label all low-voltage wires before disconnecting. Verify fuse integrity on the control board after install.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our warehouse when ordered before 3 PM EST.

Compatibility: Designed for the Carrier PY3GNA024040AA air handler. Always verify the 120V primary and 24V/40VA secondary specifications against your unit's data plate or wiring diagram before ordering. Our HVAC parts specialists are available to confirm fitment — reach out before you order if you have any questions.