OEM Carrier Control Transformer 40VA 208/240V to 24V — Model PH3ZNB036000AA

This OEM Carrier control transformer (part #HT01BD209) is the factory-specified replacement for the Carrier PH3ZNB036000AA packaged unit. The transformer steps down 208/240V line voltage to the 24V signal that powers your thermostat, control board, and every low-voltage relay in the system. When it fails — due to a short, voltage spike, or age — the entire control circuit goes dark: no thermostat response, no staging, nothing works. Replacing it with the correct OEM part restores full system function immediately.

• Specs: 208/240V Primary | 24V Secondary | 40VA | 50/60 Hz | Replaces HT01BD207, HT01CN232, 4000A46E07AE28, 9076-00
• OEM vs Generic: This is a genuine Carrier OEM transformer, factory-wound to exact VA and voltage tolerances. Generic transformers risk undervoltage on heavy control loads, causing nuisance lockouts and shortened board life.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before touching any wiring. Tools needed: flathead and Phillips screwdrivers, multimeter (confirm 0V before touching), wire nuts or spade connectors. Photograph all wiring before disconnecting. The transformer typically mounts with one screw to the cabinet panel.
• Warranty: 1-year OEM factory warranty. Ships same business day from our warehouse.

Compatibility: Direct OEM fit for Carrier model PH3ZNB036000AA. Also cross-references with Bryant and Payne units sharing the same transformer specification. Always confirm your unit's control voltage and VA rating on the equipment data plate before ordering. Have questions about fitment? Our HVAC parts specialists verify compatibility before you buy — call or chat today and get your unit back online fast.