OEM Carrier Transformer 40VA 120V to 24V for Model C4850C50AY02751

This OEM Carrier transformer (part number HT01BD236) is the factory-specified step-down transformer for the C4850C50AY02751 packaged unit. Its job is to convert 120V line voltage to the 24V AC signal that powers your thermostat, control board, contactor coil, and every other low-voltage control circuit component. When this transformer fails, the entire control circuit goes dark — the thermostat display may go blank, the system will not respond to any call for heating or cooling, and you may measure zero volts on the 24V secondary terminals with power present at the primary.

• Specs: 40VA capacity | 120V primary | 24V secondary | OEM part number HT01BD236 | Factory-matched winding tolerance for stable low-voltage output
• OEM vs Generic: OEM transformers are wound to Carrier's exact VA rating and insulation class. Undersized or off-spec generic transformers can overheat, blow internal fuses, and damage downstream control boards — a far more expensive repair than the transformer itself.
• Install difficulty: 2/5 — Shut off all power to the unit and verify voltage is absent before touching any wiring. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter. Label or photograph all wire connections before removal. Mount the replacement securely and restore wiring to primary and secondary terminals as marked.
• Warranty: 1-year OEM factory warranty. Orders placed before our same-day shipping cutoff ship from our warehouse today.

Compatibility: Designed for Carrier model C4850C50AY02751 packaged unit. Confirm your existing transformer's primary voltage (120V), secondary voltage (24V), and VA rating on the unit data plate or transformer label before ordering. Our parts specialists are available to verify fitment — reach out before you buy for total confidence.