OEM Carrier 40VA Control Transformer for Model C4850C50AJ03561

This is the factory OEM replacement control transformer (part# HT01BD236) for the Carrier C4850C50AJ03561 packaged unit. The transformer steps down 120V line voltage to the 24V AC signal required by your thermostat, contactor coil, gas valve, and all other low-voltage control components. When this transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system won't respond to any call for heating or cooling, and no safety functions will operate. It is often the first component to inspect when nothing works but line power is confirmed present.

• Specs: 40VA rating | 120V primary / 24V secondary | OEM part number HT01BD236 | Factory-matched footprint and lead configuration for drop-in installation
• OEM vs Generic: OEM transformers are wound to exact VA and impedance specs required by Carrier controls. Undersized or off-spec generic transformers can cause erratic contactor chatter, nuisance lockouts, or premature control board failure — making the OEM choice a long-term investment.
• Install difficulty: 2/5 — Always disconnect power at the disconnect and breaker before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter (to confirm 24V output after install), wire stripper. Photograph or label all low-voltage wiring before disconnecting. Most installs complete in under 30 minutes.
• Warranty: 1-year OEM factory warranty against defects. In stock and ships same business day from our climate-controlled warehouse.

Compatibility: Designed specifically for the Carrier C4850C50AJ03561 packaged unit. Verify your existing transformer's VA rating and primary/secondary voltages on the data plate or wiring diagram inside the unit's access panel before ordering. If you have any questions about fitment, our HVAC parts specialists confirm compatibility before your order ships — no guesswork required.