{"product_id":"icp-24v-transformer-for-zama004ahb3-spst-40va-control-ships-today","title":"ICP 24V Transformer for ZAMA004AHB3 — SPST 40VA Control | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis OEM 24V control transformer (ICP part #1057251) delivers the low-voltage power that operates the thermostat, relays, and control circuits in your air handler or furnace. Rated at 40VA, it steps line voltage down to 24V for the SPST control loop. When it fails, the whole 24V circuit goes dead — the thermostat blanks, relays and contactors will not energize, and the equipment will not run. Common causes include a shorted secondary winding, an overloaded control circuit, or surge-induced overheating that opens the windings.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpec\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003e1057251\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eControl Transformer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eICP (Tempstar \/ Heil)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecondary Voltage\u003c\/td\u003e\n\u003ctd\u003e24V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRating\u003c\/td\u003e\n\u003ctd\u003e40VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSwitch Action\u003c\/td\u003e\n\u003ctd\u003eSPST\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eDirect-fit replacement for ICP, Tempstar, Heil, and Comfortmaker equipment using the 1057251 control transformer, including model ZAMA004AHB3. Confirm the primary voltage and VA rating against the original part before installing.\u003c\/p\u003e\u003ch3\u003eInstallation Guide\u003c\/h3\u003e\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety First\u003c\/strong\u003e — Disconnect power and verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the control-box\/service panel to reach the transformer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph primary and secondary wiring before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the leads, unbolt the transformer from its bracket, and remove it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and reconnect primary and secondary leads per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and verify 24V across the secondary and normal operation.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eBlank thermostat or no 24V at the control board\u003c\/li\u003e\n\u003cli\u003eRelays and contactors will not energize\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage fuse\u003c\/li\u003e\n\u003cli\u003eTransformer is hot, buzzing, or visibly burned\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\u003cp\u003eShips same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.\u003c\/p\u003e","brand":"ICP","offers":[{"title":"Direct Replacement","offer_id":63021431751027,"sku":"ZAMA004AHB3-GEN","price":34.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63047947420019,"sku":"ZAMA004AHB3","price":44.2,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-ZAMA004AHB3.jpg?v=1782882037","url":"https:\/\/nationalhvacparts.com\/products\/icp-24v-transformer-for-zama004ahb3-spst-40va-control-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}