OEM Carrier 40VA Control Transformer for Model HUMBBLBP2217A — Part P201-2201

This OEM Carrier transformer (part number P201-2201) is the factory-specified replacement for the HUMBBLBP2217A HVAC system. The transformer steps down 120V line voltage to the 24V signal voltage that powers your thermostat, control board, contactor coil, and every other low-voltage component in the system. When it fails, the result is total system silence — the thermostat goes dark, nothing responds, and no fault codes are generated because the control circuit itself has lost power. A failed transformer is often misdiagnosed as a bad control board, making correct identification critical before replacing more expensive components.

• Specs: 40VA rating | 120V primary input | 24V secondary output | Factory-matched to Carrier HUMBBLBP2217A control circuit load requirements
• OEM vs Generic: This OEM unit from Carrier meets exact VA rating and insulation class specifications. Undersized generic transformers overheat under full control circuit load, leading to repeated failures and potential damage to downstream low-voltage components.
• Install Difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to confirm 0V before touching terminals and to verify 24V output after install). Label or photograph all wiring connections prior to removal.
• Warranty: 1-year OEM factory warranty against defects in materials and workmanship. In-stock and ships same business day from our NationalHVACParts.com warehouse.

Compatibility: Designed for the Carrier HUMBBLBP2217A system. Always verify your existing transformer's VA rating and primary/secondary voltages on the unit data plate or wiring diagram before ordering. If you're uncertain about fitment, our parts specialists are available to confirm compatibility before you purchase — just reach out before placing your order.