OEM Carrier 40VA Control Transformer HT01BC116 for Model PG8JAA042090AAJA

This OEM step-down control transformer is the factory-specified replacement for the Carrier PG8JAA042090AAJA packaged gas furnace. The transformer steps line voltage down from 120V to 24V AC to power the low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this component fails, the entire control circuit loses power: the thermostat goes blank, the unit will not respond to any call for heat or cool, and no other components will energize. A failed transformer often presents as a completely unresponsive system with no error codes, making it one of the most commonly overlooked diagnostics.

• Specs: 40VA rating | 120V primary / 24V secondary | Class 2 control transformer | Factory-matched to Carrier PG8JAA042090AAJA wiring harness
• OEM vs Generic: OEM transformers are wound to exact factory VA and voltage tolerances, protecting sensitive control boards from voltage fluctuations. Generic units often run outside rated VA, causing nuisance trips, board damage, or premature failure.
• Install Difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or quick-connect terminals. Verify 24V output before re-energizing the control board. Always photograph or label existing wiring before disconnecting.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Engineered for the Carrier PG8JAA042090AAJA packaged gas furnace. Confirm your unit's control circuit voltage and VA requirement on the data plate or wiring diagram before ordering. Have questions about fitment? Our HVAC parts specialists verify compatibility before you buy — reach out before placing your order.