OEM Carrier Furnace Control Transformer 40VA 120V–24V for Model PG9MAB036040AASA

This is the factory-specified OEM replacement control transformer for the Carrier PG9MAB036040AASA gas furnace, sold under OEM part number HT01BC116 (current superseding part: HT680054). The transformer steps down 120V line voltage to 24V to power the low-voltage control circuit — including the thermostat, gas valve, inducer relay, and control board. When this transformer fails, the furnace loses its entire control circuit: the thermostat goes dark, the board receives no power, and the system produces zero response to a heat call. If your furnace is completely unresponsive — no inducer, no ignition attempt, no status light blinking — a failed transformer is one of the first components to test.

• Specs: 40VA rating | 120V primary (line voltage) | 24V secondary (control voltage) | 50/60 Hz | Single-phase | Wire-lead connections | Compact 3" L × 2-3/16" W × 2" H footprint
• OEM vs Generic: This OEM transformer is wound to Carrier's exact VA and impedance specifications. Generic transformers may be under-rated for VA, causing overheating and premature failure — especially in systems with accessories like humidifiers or UV lights on the 24V circuit.
• Install difficulty: 2/5 — Turn off power at the disconnect and confirm voltage is absent before touching any wiring. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter (to verify 24V output after install). Photograph or label all 24V wire connections before removal. Replace any blown 3A fuse in the secondary circuit during the same service call.
• Warranty: 1-year OEM manufacturer warranty. In-stock units ship same business day when ordered by 5 PM local time.

Compatibility: Engineered for the Carrier PG9MAB036040AASA gas furnace. Also replaces legacy part numbers HT01BC115, HT01BB126, HT01CT120, HT01BC120, HT01AW115, HT01AA012, HT01AQ110, 322666-701, 322953-302, and B1810113. Always verify primary voltage (120V) and VA rating (40VA) on your unit's wiring diagram before ordering. Order now and we'll ship today — back to heat fast.