OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY3PPA042090NB

This OEM control transformer (part number HT01BD209) is the factory-specified replacement for the Carrier PY3PPA042090NB packaged unit. The transformer steps down line voltage (208/240V) to the 24V control circuit voltage that powers your thermostat, gas valve, contactor coil, and control board. When this part fails, the entire low-voltage control circuit goes dead — resulting in a blank thermostat, no response to calls for heating or cooling, or a tripped low-voltage fuse with no obvious cause.

• Specs: 40VA capacity | 208/240V primary input | 24V secondary output | 50/60 Hz rated | Class 2 control transformer | Replaces OEM part numbers HT01BD207, HT01CN232, and 9076-00
• OEM vs Generic: OEM transformers are wound to exact Carrier factory specifications, ensuring stable 24V output under full load. Generic alternatives may suffer voltage sag under peak demand, causing intermittent lockouts or nuisance tripping of low-voltage fuses.
• Install difficulty: 2/5 — Shut off power at the disconnect before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after installation). Label all wiring before disconnecting. Replace the low-voltage fuse if blown — the transformer may not be the sole cause.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse in original Carrier packaging.

Compatibility: Fits Carrier model PY3PPA042090NB packaged heating and cooling unit. Verify your existing transformer's primary voltage (208V or 240V) and VA rating on the data plate before ordering. Cross-references: HT01BD207, HT01CN232, 9076-00. Questions about fitment? Our HVAC parts specialists confirm compatibility before you order — call or chat today.