OEM Carrier Transformer 40VA 120V/24V for Model C4850C50ZN050500

This is the factory-specified OEM replacement transformer (part# HT01BD236) for the Carrier C4850C50ZN050500 packaged unit. The transformer steps down line voltage (120V) to the 24V low-voltage signal required by the control board, thermostat, contactor coil, and all safety circuit 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 you may measure zero voltage at the secondary terminals. It is often misdiagnosed as a control board failure, making it one of the most important first checks during a no-power service call.

• Specs: Input 120VAC | Output 24VAC | 40VA rating | OEM part number HT01BD236 | Color-coded wire leads for fast reconnection
• OEM vs Generic: OEM transformers from Carrier are wound to precise VA tolerances, protecting downstream low-voltage components from brownout or surge conditions. Generic units often underperform at rated VA, causing nuisance control board resets or premature contactor coil failure.
• Install difficulty: 2/5 — Disconnect power at the disconnect box before servicing. Tools needed: flathead and Phillips screwdrivers, multimeter (verify 0V before touching wiring), wire nuts or spade connectors. Photograph existing wiring before removal. Secondary fuse replacement recommended if original transformer was shorted.
• Warranty: 1-year OEM factory warranty. Orders placed before cutoff ship same business day from our climate-controlled warehouse.

Compatibility: Designed for the Carrier C4850C50ZN050500 packaged unit. Confirm your existing transformer's input/output voltage and VA rating on the data plate or original component label before ordering. If you're unsure of fitment, our HVAC parts specialists verify compatibility before your order ships — no guesswork required.