OEM Carrier 40VA Control Transformer HT01BD209 for Model PY3GPAA30040AA

This genuine OEM Carrier transformer (part number HT01BD209) is the factory-specified replacement for the Carrier PY3GPAA30040AA packaged unit. The control transformer steps down line voltage from 208/230V primary to a stable 24V secondary output at 40VA, powering the entire low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this transformer fails, the system goes completely unresponsive: no call-for-cooling, no call-for-heating, and no 24V signal to any downstream component. A blown fuse on the secondary side or a completely dead control board are the most common symptoms pointing directly to transformer failure.

• Specs: 208/230V Primary | 24V Secondary | 40VA Rating | 50/60 Hz | Factory OEM tolerance — direct plug-and-play fitment for PY3GPAA30040AA
• OEM vs Generic: OEM transformers maintain precise secondary voltage under load fluctuations. Generic units can sag under peak draw, causing erratic control board behavior and nuisance lockouts. This is a genuine Carrier part — no guesswork on fitment or output stability.
• Install Difficulty: 2/5 — Shut off all power at the disconnect before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire labels or tape. Always verify 0V at terminals before touching wiring. Label all low-voltage leads before disconnecting. Test secondary output (should read ~24–28V AC) after installation before closing the panel.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse when ordered before 3PM local time.

Compatibility: Confirmed fit for Carrier model PY3GPAA30040AA. Also replaces legacy Carrier part numbers HT01BD207, HT01CN232, and 9076-00. Verify your unit's data plate voltage before ordering — this transformer is rated for 208/230V primary input only. Not compatible with 460V or 575V primary applications. Questions about fitment? Our HVAC parts specialists verify compatibility before you order — no returns needed.