{"product_id":"tempstar-40va-transformer-for-t9mpd075f12c1-115v-to-24v-step-down-ships-today","title":"Tempstar 40VA Transformer for T9MPD075F12C1 — 115V to 24V Step-Down | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis genuine OEM control transformer, part #1172810, supplies low-voltage power to the Tempstar T9MPD075F12C1 gas furnace. It steps 115V line voltage down to 24V at 40VA, powering the control board, thermostat circuit, gas valve, and relays. When a transformer fails — usually from a shorted secondary, an overloaded 24V circuit, or simple age — the furnace goes completely dead at the thermostat: no display, no blower, no ignition. A blown low-voltage fuse on the control board that pops repeatedly is also a classic sign of a failing transformer or a short downstream of it. This 40VA OEM unit matches the original mounting, primary\/secondary voltages, and VA rating for a direct replacement.\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\u003e1172810\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eStep-Down Control Transformer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eTempstar (ICP \/ Heil)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Voltage\u003c\/td\u003e\n\u003ctd\u003e115V\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\u003e40 VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFit\u003c\/td\u003e\n\u003ctd\u003eOEM Direct Replacement\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eBuilt for the Tempstar T9MPD075F12C1 gas furnace and other ICP-family units (Heil, Comfortmaker, Day \u0026amp; Night) that use a 115V-to-24V 40VA transformer. Verify primary\/secondary voltage and VA rating against your original.\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-compartment service panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph the primary and secondary wiring before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and disconnect the leads, then unbolt the old transformer from the mounting plate.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and reconnect primary (115V) and secondary (24V) leads exactly per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V at the secondary, then run a full heat cycle.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eFurnace completely dead — no thermostat or control display\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown 24V control-board fuse\u003c\/li\u003e\n\u003cli\u003eNo measurable 24V output at the secondary terminals\u003c\/li\u003e\n\u003cli\u003eBurnt smell or visible scorching on the transformer body\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\u003cp\u003eShips same day on orders placed before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.\u003c\/p\u003e","brand":"Tempstar","offers":[{"title":"Direct Replacement","offer_id":63021681017203,"sku":"1172810-GEN","price":26.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048406827379,"sku":"1172810","price":33.8,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_8add1c08-d812-445a-ba50-44bcbaf08f04.jpg?v=1782958385","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-t9mpd075f12c1-115v-to-24v-step-down-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}