{"product_id":"tempstar-transformer-for-t9uhx100l20a2-40va-115v-to-24v-ships-today","title":"Tempstar Transformer for T9UHX100L20A2 — 40VA 115V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis OEM control transformer (part #1172810) steps 115 volts down to the 24-volt control voltage that runs the thermostat, gas valve, and control board in your Tempstar T9UHX100L20A2 furnace. Rated at 40VA, it supplies the low-voltage circuit that ties the entire heating and cooling control system together. When a transformer fails — usually from a shorted low-voltage wire, a stuck contactor, or simple age — the furnace goes completely dead with no thermostat display and no response to a heat or cool call. A blown transformer often accompanies a shorted thermostat wire, so inspect the 24V wiring before replacing.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\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\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\u003e115 VAC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecondary Voltage\u003c\/td\u003e\n\u003ctd\u003e24 VAC\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\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cp\u003eDirect OEM replacement for the Tempstar T9UHX100L20A2 furnace and matching ICP\/Heil\/Comfortmaker boards that use a 40VA 115-to-24V control transformer. Verify the VA rating and primary\/secondary voltages on your old transformer before installing.\u003c\/p\u003e\n\n\u003ch3\u003eInstallation Guide\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety First\u003c\/strong\u003e — Disconnect power to the furnace and verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the furnace service panel to reach the control box.\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 primary and secondary leads and unbolt the transformer from its mounting tab.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and reconnect the 115V primary and 24V secondary leads per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24 VAC at the secondary and a live thermostat.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eFurnace completely dead with a blank thermostat\u003c\/li\u003e\n\u003cli\u003eNo 24V reading at the secondary terminals\u003c\/li\u003e\n\u003cli\u003eBurnt smell or visibly charred transformer windings\u003c\/li\u003e\n\u003cli\u003eRepeated blown low-voltage fuses\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\n\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":63021676659059,"sku":"1172810-GEN","price":27.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048490910067,"sku":"1172810","price":35.1,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_ab1f64ea-58af-4fbc-a0e6-7e42089c88b4.jpg?v=1782961454","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-transformer-for-t9uhx100l20a2-40va-115v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}