OEM Carrier 50VA Control Transformer P201-35150 for Model YAC1840YACX501K

This is the genuine OEM step-down transformer for the Carrier YAC1840YACX501K, sold under Carrier part number P201-35150 (also catalogued as a Totaline part). The transformer converts high-voltage line power — 120V, 208V, or 240V AC — down to a safe 12/24V AC output that powers your system's control board, thermostat, and all low-voltage switching circuits. When this transformer fails, the entire control circuit goes dark: the thermostat goes blank, the system becomes completely unresponsive, and no heating or cooling call can be processed. A failed transformer is often mistaken for a bad control board, so always verify transformer output voltage first before replacing more expensive components.

• Specs: 50 VA rating | Primary voltage: 120/208/240 VAC multi-tap | Secondary voltage: 12/24 VAC | 60 Hz single-phase | CSA listed | Dimensions: 3.8"L × 3.1"W × 2.2"H
• OEM vs Generic: This factory-authorized OEM unit is wound to exact VA and voltage tolerance specifications. Generic transformers frequently use lower-grade core laminations that run hotter, degrade faster under load, and can produce voltage sag that causes nuisance lockouts on sensitive control boards.
• Install difficulty: 3/5 — Line voltage is present at the primary terminals. Shut off power at the breaker and verify with a multimeter before touching any wiring. Tools needed: flathead and Phillips screwdrivers, needle-nose pliers, multimeter, wire nuts or spade terminals. Photograph all wiring connections before disconnecting. Confirm secondary output voltage (should read ~24V AC) after installation before closing the panel.
• Warranty: 1-year OEM manufacturer warranty. In-stock and ships same business day from our warehouse.

Compatibility: Factory-specified replacement for Carrier model YAC1840YACX501K. The multi-tap primary (120/208/240V) makes this transformer suitable across a wide range of Carrier equipment sharing the P201-35150 specification — always confirm your unit's supply voltage and VA requirement on the data plate before ordering. Need help verifying fitment? Our HVAC parts specialists are standing by.