OEM Carrier 24V Control Transformer HT01BD209 for Model PY3GNA036090AA

This OEM control transformer (part number HT01BD209) is the factory-specified replacement for the Carrier PY3GNA036090AA packaged HVAC unit. The transformer steps down 120V line voltage to 24V AC, powering the entire low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this transformer fails, the entire system goes dark: the thermostat loses power, no relays energize, and nothing operates. A blown transformer is often the first sign of a shorted wire or faulty component elsewhere in the 24V circuit, so always inspect the low-voltage wiring before installing a replacement.

• Specs: Primary: 120V AC | Secondary: 24V AC | VA rating: 40VA (typical factory spec) | Terminal-style connections | UL-recognized component | Factory-matched for Carrier PY3GNA036090AA
• OEM vs Generic: This OEM unit is wound to Carrier's exact VA and impedance specifications. Generic transformers are often under-rated in VA, causing overheating and premature failure — especially on systems with multiple 24V loads such as zone boards or dual-fuel controls.
• Install difficulty: 2/5 — Shut off power at the disconnect and breaker before starting. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output after install and to check for shorts before energizing). Always confirm no short circuit exists in the 24V circuit before installing a new transformer.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Engineered as a direct OEM replacement for Carrier model PY3GNA036090AA. Verify your unit's control circuit voltage and VA requirements on the data plate before ordering. If your old transformer shows signs of burn marks or a tripped internal fuse, inspect all downstream 24V wiring for shorts before powering up. Need fitment confirmation? Our HVAC parts specialists verify compatibility before every order.