OEM Carrier Control Transformer 40VA 120V to 24V for Model C4850C48ZG055200

This is the factory OEM replacement control transformer (part number HT01BD236) for the Carrier C4850C48ZG055200 packaged unit. The transformer steps down line voltage from 120V to 24V to power the entire low-voltage control circuit — including the thermostat, contactor coil, gas valve, and control board. When this transformer fails, the result is total system non-response: the thermostat goes blank, no calls for heating or cooling are answered, and no error codes are generated because the control circuit has no power. A failed transformer is often misdiagnosed as a bad thermostat or control board, making it the first component to test in a completely non-responsive unit.

• Specs: 40VA rated | Primary voltage: 120V | Secondary voltage: 24V | OEM part number HT01BD236 | Carrier-matched output tolerance for stable control circuit operation
• OEM vs Generic: This OEM transformer is wound to Carrier's exact VA and voltage specifications. Generic transformers often run under-rated VA loads, causing premature overheating, blown fuses, and repeat failures — especially in multi-stage systems with higher 24V current draw.
• Install difficulty: 2/5 — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter, wire nuts. Label all low-voltage wiring before disconnecting. Test secondary output voltage (should read 24–28V AC) after installation to confirm proper operation.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our warehouse.

Compatibility: Designed as a direct OEM replacement for Carrier model C4850C48ZG055200 packaged units. Verify your existing transformer's VA rating and primary/secondary voltages against your unit's data plate before ordering. Not sure if this part fits your unit? Our HVAC parts specialists verify fitment — contact us before you order. In stock and ships today.