{"product_id":"tempstar-40va-transformer-for-t9mpd075f12a3-115v-to-24v-control-transformer-ships-today","title":"Tempstar 40VA Transformer for T9MPD075F12A3 — 115V to 24V Control Transformer | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is the OEM control transformer (OEM #1012722, \"TRANS 115\u0026gt;24 40VA\") for the Tempstar T9MPD075F12A3 gas furnace. The transformer steps the incoming 115V line voltage down to the 24V low-voltage control circuit that powers the thermostat, control board logic, gas valve, and relays. Rated at 40VA, it supplies enough current for the furnace's controls plus a typical thermostat and accessory load. When a transformer fails — usually from a shorted secondary, a stuck contactor pulling excess current, or simple age — the entire 24V control system goes dead: the thermostat screen blanks, nothing energizes, and the furnace appears completely unresponsive even though line power is present. A blown transformer is also frequently a symptom of a downstream short, so inspect the low-voltage wiring before energizing the 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\u003e1012722\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\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\u003e40VA\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\u003eFitment\u003c\/td\u003e\n\u003ctd\u003eOEM\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 T9MPD075F12A3 furnace and used across ICP-family equipment (Tempstar, Heil, Comfortmaker) that specifies the 1012722 40VA 115\/24 transformer. Verify primary voltage and VA against your unit before installing.\u003c\/p\u003e\u003ch3\u003eInstallation Guide\u003c\/h3\u003e\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety First\u003c\/strong\u003e — Disconnect furnace power at the breaker and confirm 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 (line) and secondary (24V) wire connections before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the leads, remove the mounting screw or bracket, and take out the failed transformer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, land the 115V primary and 24V secondary leads exactly per your photo, and confirm tight connections.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and verify 24V across the secondary; confirm the thermostat powers up and the furnace sequences normally.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eThermostat is blank and the furnace is completely dead despite line power.\u003c\/li\u003e\n\u003cli\u003eNo 24V reading at the control board or thermostat terminals.\u003c\/li\u003e\n\u003cli\u003eTransformer is hot, buzzing, or shows scorch marks.\u003c\/li\u003e\n\u003cli\u003eFurnace works intermittently then loses all control power.\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":"Tempstar","offers":[{"title":"Direct Replacement","offer_id":63021681213811,"sku":"1012722-GEN","price":24.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048406761843,"sku":"1012722","price":32.44,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1012722_82ce4650-09ac-42be-bc6d-ab91364132c0.jpg?v=1782958383","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-t9mpd075f12a3-115v-to-24v-control-transformer-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}