{"product_id":"carrier-c4850c48ay03551-transformer-h302a1","title":"OEM Carrier Transformer 40VA 120V\/24V for C4850C48AY03551","description":"\u003ch1\u003eOEM Carrier Transformer 40VA 120V\/24V for Model C4850C48AY03551\u003c\/h1\u003e\u003cp\u003eThis OEM step-down transformer (part# HT01BD236) is the factory-specified replacement for the \u003cstrong\u003eCarrier C4850C48AY03551\u003c\/strong\u003e packaged unit. The transformer converts 120V line voltage to the 24V signal voltage that powers your thermostat, control board, contactor coil, and all low-voltage control circuits. When the transformer fails, the entire control circuit goes dark — your thermostat shows no response, relays won't energize, and the system refuses to start in any mode. If you've already confirmed your thermostat and control board are intact, a failed transformer is the most common culprit for a completely unresponsive unit.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpecs:\u003c\/strong\u003e Input 120V AC | Output 24V AC | 40VA rated | OEM part number HT01BD236 | Factory-matched for exact fit and electrical performance\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM vs Generic:\u003c\/strong\u003e OEM transformers are wound to precise VA tolerances for your specific unit. Undersized or off-brand transformers can sag under load, causing erratic control board behavior, nuisance lockouts, and premature contactor coil failure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall difficulty: 2\/5\u003c\/strong\u003e — Disconnect power at the breaker before beginning. Tools needed: flathead and Phillips screwdrivers, multimeter, wire nuts or spade connectors. Verify 0V at transformer primary terminals before touching any wiring. Label or photograph all wire connections before removal.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWarranty:\u003c\/strong\u003e 1-year OEM factory warranty. In-stock units ship same business day from our warehouse when ordered before cutoff.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Designed for Carrier model \u003cstrong\u003eC4850C48AY03551\u003c\/strong\u003e packaged units. Confirm your existing transformer's input\/output voltage and VA rating on the unit data plate or transformer label before ordering. Our fitment team is available to verify compatibility before you buy — just reach out with your full model and serial number. \u003cstrong\u003eOrder today and your part ships same business day.\u003c\/strong\u003e\u003c\/p\u003e","brand":"Carrier","offers":[{"title":"OEM","offer_id":62909882892659,"sku":"CARRIE-C4850C48AY03551-TRANSFORMER-HT01BD236","price":47.25,"currency_code":"USD","in_stock":true},{"title":"Generic","offer_id":62909882925427,"sku":"CARRIE-C4850C48AY03551-TRANSFORMER-HT01BD236-GEN","price":18.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-HT01BD236_b4e47f5b-01d3-41d4-a128-8fe3ae72bdba.jpg?v=1782940044","url":"https:\/\/nationalhvacparts.com\/products\/carrier-c4850c48ay03551-transformer-h302a1","provider":"National HVAC Parts","version":"1.0","type":"link"}