{"product_id":"carrier-ph3zna030000aa-transformer-h3025m","title":"OEM Carrier 75VA Transformer 240\/480V–24V for PH3ZNA030000AA","description":"\u003ch1\u003eOEM Carrier 75VA Control Transformer HT01BD242 for Model PH3ZNA030000AA\u003c\/h1\u003e\u003cp\u003eThis is the factory OEM replacement control transformer for the \u003cstrong\u003eCarrier PH3ZNA030000AA\u003c\/strong\u003e packaged unit. The transformer steps down the high-voltage primary supply (208\/240\/480V) to the 24VAC secondary signal that powers the entire control circuit — including the thermostat, contactor coil, gas valve, and all safety switches. When this transformer fails, nothing in the system responds: the thermostat goes blank, the unit won't stage heating or cooling, and there are no error codes because the control board itself has lost power. A failed transformer is often misdiagnosed as a board failure, so always verify 24V output at the secondary terminals before replacing more expensive components.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpecs:\u003c\/strong\u003e Primary 208\/240\/480VAC | Secondary 24VAC | 75VA rated | 50\/60Hz | Foot-mount configuration | OEM part number HT01BD242\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM vs Generic:\u003c\/strong\u003e This is a genuine Carrier OEM transformer wound to exact factory VA and voltage tolerances. Undersized or off-tolerance aftermarket transformers can sag under load, causing intermittent lockouts and nuisance tripping of low-voltage fuses — especially in multi-stage systems with higher control circuit draw.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall difficulty: 3\/5\u003c\/strong\u003e — Disconnect all power before servicing. Tools needed: multimeter (verify 0V at primary before touching wiring), wire strippers, screwdriver, and needle-nose pliers. Label all low-voltage wires before disconnecting. Check for a blown 3A inline fuse on the secondary — a shorted wire is often what burned the original transformer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWarranty:\u003c\/strong\u003e 1-year OEM factory warranty. In-stock orders ship same business day from our warehouse.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Designed for the \u003cstrong\u003eCarrier PH3ZNA030000AA\u003c\/strong\u003e packaged unit. Also cross-references to Bryant, Payne, ICP, Heil, Tempstar, and Comfortmaker units sharing the HT01BD242 specification. Verify your unit's primary voltage (208\/240V or 480V) on the data plate before ordering — voltage must match. Questions about fitment? Our HVAC parts specialists verify compatibility before you order.\u003c\/p\u003e","brand":"Carrier","offers":[{"title":"OEM","offer_id":62641342873971,"sku":"CARRIE-PH3ZNA030000AA-TRANSFORMER-HT01BD242","price":99.99,"currency_code":"USD","in_stock":true},{"title":"Generic","offer_id":62641342906739,"sku":"CARRIE-PH3ZNA030000AA-TRANSFORMER-HT01BD242-GEN","price":87.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-HT01BD242_f6594104-15c4-47f0-855a-6ac5e9e43bf1.jpg?v=1775016753","url":"https:\/\/nationalhvacparts.com\/products\/carrier-ph3zna030000aa-transformer-h3025m","provider":"National HVAC Parts","version":"1.0","type":"link"}