OEM Carrier Control Transformer 40VA 208/240V to 24V — Model PY3PPA030040NB

The Carrier HT01BD209 is the factory-specified 40VA control transformer for the PY3PPA030040NB packaged unit. Its sole but critical job is to step down the 208/240V line voltage to the 24V signal needed to power every low-voltage control circuit in your system — thermostat, control board, contactor coil, and all safety switches. When this transformer fails, the entire control circuit goes dark: the thermostat goes blank, the system refuses to respond to any call for heating or cooling, and no components will energize. It is frequently the first part to check when a unit appears completely dead despite having line voltage at the disconnect.

• Specs: 40VA power rating | Input: 208/240V primary | Output: 24V secondary | Frequency: 50/60 Hz | OEM Part #: HT01BD209
• OEM vs Generic: This OEM unit is wound to factory tolerances, ensuring stable 24V output under full VA load. Generic transformers can sag under load, causing erratic board resets, nuisance lockouts, and premature contactor coil failure.
• Install Difficulty: 2/5 — Turn off ALL power at the disconnect and breaker before touching any wiring. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label all low-voltage wires before disconnecting. Verify 24V output with a meter before buttoning up the unit.
• Warranty: 1-year OEM factory warranty against defects. Ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PY3PPA030040NB packaged units. Verify your unit's data plate shows a 208/240V primary and 24V secondary control circuit before ordering. Not sure it fits? Our HVAC parts specialists verify fitment before you order — order with confidence and get back up and running today.