OEM Carrier 40VA Control Transformer 208/230V to 24V for Model PY3GPAA42090NA

This is the factory-specified OEM control transformer (part number HT01BD209) for the Carrier PY3GPAA42090NA packaged HVAC unit. The transformer steps down 208/230V line voltage to the 24V signal required to power the thermostat, control board, contactor coil, and all low-voltage components. When this transformer fails, the entire control circuit goes dark — symptoms include a completely unresponsive thermostat, a system that won't call for heating or cooling, and a control board that shows no status LED activity. This is one of the first parts to test when nothing appears to work at all.

• Specs: 208/230V Primary | 24V Secondary | 40VA capacity | 50/60Hz | Class 2 control transformer | Direct OEM replacement for HT01BD207, HT01CN232, and 9076-00
• OEM vs Generic: OEM transformers are wound to exact VA tolerance, ensuring the 24V secondary holds steady under full control-circuit load. Undersized or off-spec generics can sag under load, causing erratic board behavior, nuisance lockouts, or premature contactor failure.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label all low-voltage wires before disconnecting. Verify 24V output at secondary terminals after install before restoring full power.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Engineered as the direct OEM replacement for Carrier model PY3GPAA42090NA. Also replaces obsolete Carrier part numbers HT01BD207, HT01CN232, and 9076-00. Confirm primary voltage matches your unit's supply voltage (208V or 230V) before ordering — check the data plate inside the unit's electrical panel. Need help verifying fitment? Our HVAC parts team is standing by to confirm before you order.