OEM Carrier 40VA Control Transformer 120V–24V for Model PG9MAB036040LBSA

This OEM Carrier control transformer (part number HT01BC116, updated successor HT680054) is the factory-specified step-down transformer for the Carrier PG9MAB036040LBSA gas furnace. Its job is to convert 120V AC line voltage down to 24V AC to power all low-voltage control circuits — including the thermostat, ignition board, gas valve, and safety switches. When this transformer fails, the entire control circuit goes dark: the thermostat shows no response, the furnace won't attempt ignition, and no error codes appear because there's simply no power to run them.

• Specs: Input: 120V AC (compatible 110–125V AC range) | Output: 24V AC | Rating: 40VA | Mounting: Foot-mount | Connection: Wire leads | Frequency: 60Hz
• OEM vs Generic: OEM transformers are wound to exact VA and voltage tolerances required by the Carrier PG9MAB036040LBSA control board. Undersized or off-tolerance generic units can overheat, trip thermal cutoffs, or cause erratic low-voltage behavior that mimics board or thermostat failure — wasting time and money chasing the wrong fault.
• Install Difficulty: 2/5 — Shut off power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdriver, needle-nose pliers, multimeter (verify 0V before touching leads). Label or photograph all wire connections before removal. The foot-mount bracket lines up directly with the original mounting holes for a clean swap.
• Warranty & Shipping: 1-year OEM warranty against defects. Ships same business day from our warehouse — order by 3PM local time to go out today.

Compatibility Note: Designed for the Carrier PG9MAB036040LBSA gas furnace. This part also carries cross-reference numbers HT01BC116B, HT01BC115, HT01BB126, HT01CT120, HT01BC120, and HT01AW115 — confirm your existing transformer's input/output voltage and VA rating on the data plate before ordering. Need fitment confirmation? Our HVAC parts team verifies compatibility before you buy — reach out before placing your order.