OEM Carrier 40VA Control Transformer 208/240V to 24V — HT01BD209 for Model PH3ZNB036000AB

This OEM Carrier transformer (part # HT01BD209) is the factory-specified replacement for the Carrier PH3ZNB036000AB packaged unit. The control transformer steps down 208/240V line voltage to the 24V AC signal that powers your thermostat, contactor coil, and all low-voltage control circuits. When this part fails, the result is total control-circuit loss — a blank thermostat, an unresponsive system, or a tripped low-voltage fuse with no clear upstream cause. Replacing a failed transformer is one of the most cost-effective service calls in the field.

• Specs: Input 208/240V | Output 24V AC | 40VA power rating | 50/60Hz | Direct OEM replacement for Carrier PH3ZNB036000AB
• OEM vs Generic: OEM transformers are wound to exact VA tolerances, preventing voltage sag under full control-circuit load. Undersized or off-tolerance aftermarket units can cause intermittent lockouts and premature contactor coil burnout.
• Install difficulty: 2/5 — Shut off all power at the disconnect and breaker before beginning. Tools needed: flathead and Phillips screwdrivers, wire stripper, multimeter. Note wire lead colors and connection points before disconnecting the old unit. Total repair time: 20–35 minutes.
• Warranty: 1-year OEM factory warranty. In stock — ships same business day from our warehouse.

Compatibility: Engineered for Carrier model PH3ZNB036000AB packaged units. Verify input voltage on your unit's data plate (208V or 240V) matches your supply circuit before ordering. Not sure about fitment? Our HVAC parts specialists verify compatibility before you buy — contact us today and we'll get your system back online fast.