OEM Carrier 40VA Control Transformer 208/240V to 24V for Model PY2PNB030040AA

This OEM Carrier transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PY2PNB030040AA packaged unit. The transformer steps down line voltage (208/240V) to the 24V signal voltage that powers the thermostat, control board, contactors, and every other low-voltage control circuit in the system. When it fails, nothing works — the thermostat goes blank, the system refuses to respond to any call for heating or cooling, and you may measure zero volts on the secondary terminals. It is one of the first components to test during any no-response, no-power diagnostic.

• Specs: 208/240V primary input | 24V secondary output | 40VA power rating | 50/60Hz | Factory OEM part number HT01BD209
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances specified by Carrier's engineering. Undersized or off-tolerance aftermarket units can cause nuisance trips, brownout conditions on the 24V circuit, and premature control board failure.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 0V before touching wiring and to confirm 24V output after install). Photograph all wiring connections before disconnecting the old unit. Secure all wire nuts and verify no shorts before restoring power.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Direct OEM replacement for Carrier model PY2PNB030040AA. Always verify your unit's data plate voltage matches the 208/240V primary input before ordering. Have your model and serial number ready? Our fitment team is standing by to confirm compatibility before you buy — order with confidence and get back up and running today.