{"product_id":"carrier-c4850c48ay02551-transformer-h302a1","title":"OEM Carrier Transformer 40VA 120V-24V for C4850C48AY02551","description":"\u003ch1\u003eOEM Carrier 40VA Control Transformer for Model C4850C48AY02551\u003c\/h1\u003e\u003cp\u003eThis is the OEM factory-specified control circuit transformer (part# \u003cstrong\u003eHT01BD236\u003c\/strong\u003e) for the \u003cstrong\u003eCarrier C4850C48AY02551\u003c\/strong\u003e packaged unit. The transformer steps down line voltage (120V) to the 24V AC signal required to power the thermostat, control board, contactor coil, and all low-voltage safety circuits. When the transformer fails, the entire control circuit goes dead — the thermostat goes blank, the system refuses to respond to any call for heating or cooling, and no contactors or valves will energize. A failed transformer is often misdiagnosed as a control board or thermostat issue, so always verify 24V output at the secondary terminals before replacing other components.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpecs:\u003c\/strong\u003e 40VA rating | Primary: 120V AC | Secondary: 24V AC | OEM part number HT01BD236 | Factory-matched for Carrier C4850C48AY02551 packaged units\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM vs Generic:\u003c\/strong\u003e OEM transformers are wound to exact VA and voltage tolerances, ensuring stable 24V output under full load. Undersized or off-tolerance generic transformers can overheat, trip their internal fuse, or deliver low voltage that causes erratic relay and board behavior.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall difficulty: 2\/5\u003c\/strong\u003e — Shut off all power to the unit before beginning. Tools needed: multimeter, flathead and Phillips screwdrivers, wire nuts or spade connectors. Test secondary output (24V ±10%) before powering on. Always check for a shorted low-voltage wire that may have blown the original transformer before installing the new one.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWarranty:\u003c\/strong\u003e 1-year OEM factory warranty. In stock and ships same business day from our warehouse.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eCompatibility:\u003c\/strong\u003e This transformer is factory-specified for the \u003cstrong\u003eCarrier C4850C48AY02551\u003c\/strong\u003e packaged unit. Confirm your unit's data plate shows 120V control circuit voltage and cross-reference OEM part number \u003cstrong\u003eHT01BD236\u003c\/strong\u003e before ordering. Need fitment confirmation? Our HVAC parts specialists verify compatibility before you buy — just reach out before placing your order.\u003c\/p\u003e","brand":"Carrier","offers":[{"title":"OEM","offer_id":62909885153651,"sku":"CARRIE-C4850C48AY02551-TRANSFORMER-HT01BD236","price":47.25,"currency_code":"USD","in_stock":true},{"title":"Generic","offer_id":62909885186419,"sku":"CARRIE-C4850C48AY02551-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_ef3d185c-0453-4195-b354-7863a7ade3ff.jpg?v=1782939256","url":"https:\/\/nationalhvacparts.com\/products\/carrier-c4850c48ay02551-transformer-h302a1","provider":"National HVAC Parts","version":"1.0","type":"link"}