OEM Carrier Control Transformer 40VA 208/240V to 24V for Model PY4GNAA48090AA

This OEM Carrier control transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PY4GNAA48090AA packaged unit. The transformer steps down the primary line voltage (208/240V) to a 24V secondary signal that powers the entire low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this part fails, the result is typically a completely unresponsive system: no thermostat communication, no staging, and no heat or cooling output. A failed transformer may also blow the 3A fuse on the control board, making it critical to test and replace the transformer before resetting any fuses.

• Specs: 208/240V primary input | 24V secondary output | 40VA power rating | 50/60 Hz | OEM part number HT01BD209
• OEM vs Generic: The OEM HT01BD209 is wound to exact Carrier factory tolerances, ensuring stable 24V output under full load. Generic transformers can sag under load, causing intermittent lockouts, nuisance tripping, or premature control board failure.
• Install difficulty: 2/5 — Shut off all power at the breaker and disconnect switch before servicing. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label or photograph all wiring connections before removal. Verify secondary output voltage with a multimeter before reassembling the unit.
• Warranty: 1-year OEM factory warranty included. Ships same business day from our warehouse when ordered before 3 PM local time.

Compatibility: Direct OEM replacement for the Carrier PY4GNAA48090AA packaged unit. Verify your unit's data plate voltage configuration before ordering — this transformer is rated for 208/240V primary input only. Questions about fitment? Our HVAC parts specialists verify compatibility before you order. Order now and get same-day shipping!