OEM Carrier 24V Control Transformer HT01BD242 for Model PH4GNAA24000AA

This is the factory OEM replacement transformer for the Carrier PH4GNAA24000AA packaged heating and cooling unit. The transformer steps down the 120V line voltage to 24V to power the entire low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this part fails, the system will appear completely unresponsive: the thermostat goes blank, no relays click, and nothing starts. It is one of the most fundamental components in the control circuit, and a failed transformer is often misdiagnosed as a bad thermostat or control board.

• Specs: Input 120V AC | Output 24V AC | Typical VA rating 40VA | Factory-matched OEM replacement for part number HT01BD242
• OEM vs Generic: OEM transformers are wound to exact VA and impedance tolerances for this unit. Undersized or off-tolerance generic transformers can overheat, blow the secondary fuse, or introduce voltage sag that causes erratic system behavior.
• Install difficulty: 2/5 — Shut off all power to the unit before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Label all wires before disconnecting. Verify 24V output with a multimeter before reassembling panel.
• Warranty: 1-year OEM factory warranty. In-stock and ships same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for Carrier model PH4GNAA24000AA. Always confirm your existing transformer's input voltage, output voltage, and VA rating against your unit's data plate before ordering. Have questions about fitment? Our HVAC parts specialists verify compatibility before you buy — no guesswork.