OEM Carrier 40VA Control Transformer HT01BD209 for Model PY3PNA030040NA

This OEM Carrier transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PY3PNA030040NA packaged unit. The control transformer steps down line voltage from 208/240V to the 24V signal voltage that powers your thermostat, contactor coils, gas valve, and control board. When this transformer fails, the entire low-voltage control circuit goes dead — the thermostat goes blank, the system won't respond to any call for heating or cooling, and nothing runs. It is often one of the first components to check when you have a completely unresponsive system despite confirmed line voltage at the unit.

• Specs: 208/240V primary input | 24V secondary output | 40VA power rating | 50/60Hz | OEM part #HT01BD209 — factory-matched for exact fit and performance
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact VA and voltage tolerances. Aftermarket units often run marginal VA ratings that sag under load, causing nuisance control board lockouts and premature contactor coil failures.
• Install difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Photograph or label all wire connections before removing the old transformer. Verify 24V output with a multimeter before reassembling panels.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Designed for the Carrier PY3PNA030040NA packaged unit. Always verify your unit's data plate voltage and VA requirements before ordering. Not sure if this part fits your system? Our HVAC parts specialists verify fitment before you buy — contact us today and get your system back online fast.