{"product_id":"tempstar-40va-transformer-for-t8mpv100j20c1-115v-to-24v-ships-today","title":"Tempstar 40VA Transformer for T8MPV100J20C1 — 115V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is the OEM 40VA control transformer (part 1172810) for the Tempstar T8MPV100J20C1 gas furnace. It steps the incoming 115V line voltage down to the 24V low-voltage power that runs the control board, thermostat, gas valve, and relays. When a transformer fails — often from a shorted thermostat wire or a stuck contactor pulling too much current — the entire 24V control circuit goes dead and the furnace will not respond to a call for heat. A blown internal fuse or a burnt-smelling, discolored transformer body are common signs.\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 \/ Heil \/ ICP\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\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\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eFits the Tempstar T8MPV100J20C1 furnace and shared ICP\/Heil platform models using a 40VA 115V-to-24V transformer. Verify the original part number 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-compartment service panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photo all primary and secondary leads before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and disconnect the wires, then unbolt the old transformer from its mounting bracket.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and reconnect primary (115V) and secondary (24V) leads per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V across the secondary, then run a heat cycle.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eNo 24V power — furnace completely unresponsive to the thermostat\u003c\/li\u003e\n\u003cli\u003eBurnt smell or discolored transformer housing\u003c\/li\u003e\n\u003cli\u003eRepeated blown low-voltage fuse on the control board\u003c\/li\u003e\n\u003cli\u003eMeasured secondary voltage well below 24V\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":63021691666803,"sku":"1172810-GEN","price":32.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048406139251,"sku":"1172810","price":42.84,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_d24ba249-3121-470e-b5a6-048b18d1f00d.jpg?v=1782958357","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-t8mpv100j20c1-115v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}