OEM Carrier Control Transformer 208/240V to 24V 40VA — HT01BD209 for Model PY3PPA036090AB

The Carrier HT01BD209 is the factory OEM control transformer for the PY3PPA036090AB packaged unit. This transformer steps down the 208/240V line-side supply voltage to the 24V AC signal that powers your thermostat, control board, contactors, and all low-voltage safety circuits. When this transformer fails — due to a shorted control wire, a failed board drawing excess current, or simple age — the entire low-voltage control circuit goes dead: the thermostat goes blank, the system won't respond to any call for heating or cooling, and in many cases the system appears completely non-functional even though the main power supply is intact.

• Specs: Input (Primary) Voltage: 208/240V | Output (Secondary) Voltage: 24V | Frequency: 50/60 Hz | Power Rating: 40VA | OEM Part Number: HT01BD209
• OEM vs Generic: This is a genuine Carrier OEM transformer wound to exact factory VA and voltage tolerances. Generic replacements can run under-rated VA, causing nuisance tripping, overheating, and premature failure of the control board it's meant to protect.
• Install Difficulty: 2/5 — Shut off all power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter (to verify 24V output after install), wire stripper. Label or photograph all low-voltage wiring before disconnecting. Always check for a shorted low-voltage wire before installing a new transformer — the short that killed the original will destroy a new one immediately.
• Warranty: 1-year OEM factory warranty. In stock and ships same business day from our warehouse.

Compatibility: Directly fits Carrier model PY3PPA036090AB. The HT01BD209 is also a direct OEM replacement for superseded part number HT01CN232. Verify your unit's data plate input voltage before ordering. Our fitment team is available to confirm compatibility before you buy — order with confidence today.