OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY4GNAA42090AA

This OEM Carrier control transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PY4GNAA42090AA packaged unit. The transformer steps down line voltage (208/240V) to the 24V signal used by your thermostat, control board, contactor coil, and every other low-voltage component in the system. When this part 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 lost power.

• Specs: 40VA capacity | 208/240V primary | 24V secondary | 50/60 Hz | OEM part #HT01BD209 | Replaces HT01BD207, HT01CN232, 9076-00
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact factory VA and voltage tolerances. Generic units often use thinner windings and lower-grade core laminations, leading to premature thermal failure and control circuit instability.
• Install difficulty: 2/5 — Always shut off power at the breaker and confirm with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, wire strippers, multimeter. Label or photograph all wire connections before disconnecting the old unit.
• Warranty: 1-year OEM manufacturer warranty. Ships same business day from our warehouse.

Compatibility: Engineered for the Carrier PY4GNAA42090AA packaged unit. Verify your unit's model and serial number on the data plate before ordering. Cross-reference part numbers HT01BD207, HT01CN232, or 9076-00 if you are replacing an older unit. Questions about fitment? Our HVAC parts specialists verify compatibility before you order — in stock and ships today.