{"product_id":"icp-40va-transformer-for-wfml090b042b1-120v-to-24v-furnace-control-ships-today-1","title":"ICP 40VA Transformer for WFML090B042B1 — 120V to 24V Furnace Control | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis OEM 40VA control transformer (part 1177217) steps 120V line voltage down to 24V to power the low-voltage control circuit of the ICP \/ Tempstar \/ Heil WFML090B042B1 gas furnace. The transformer is what energizes the thermostat, control board, gas valve, and relays — without a healthy 24V output, nothing in the control system responds. Rated at 40VA with a 120V primary and 24V secondary, it supplies enough capacity for the furnace controls plus a connected cooling contactor or accessory. When a transformer fails — often from a short downstream, a stuck contactor, or simple age — the furnace goes completely dead: no thermostat display, no inducer, no ignition. Symptoms include a blank or unpowered thermostat, a furnace that won't respond to any call, a blown low-voltage fuse on the control board, or a burnt smell near the transformer.\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\u003e1177217\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\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\u003e120V\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\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eICP \/ Tempstar \/ Heil\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFitment\u003c\/td\u003e\n\u003ctd\u003eOEM Direct Replacement\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 fit for the ICP \/ Tempstar \/ Heil WFML090B042B1 gas furnace. The 40VA 120V-to-24V rating is shared across many ICP-built WFML-series furnaces sold under the Tempstar, Heil, and Comfortmaker brands. Confirm your model and the transformer's VA and voltage ratings before ordering.\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 at the furnace switch and breaker, and verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the furnace electrical access panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph all primary (120V) and secondary (24V) wire connections before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the wiring, unbolt the transformer from its mounting tab, and lift it out.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, then reconnect the 120V primary and 24V secondary leads exactly per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, confirm 24V at the secondary with a meter, and verify the thermostat and furnace respond normally.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eThermostat is blank or completely unpowered.\u003c\/li\u003e\n\u003cli\u003eFurnace is dead and does not respond to any call for heat.\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage fuse on the control board.\u003c\/li\u003e\n\u003cli\u003eBurnt smell or visible scorching at the transformer.\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":"ICP","offers":[{"title":"Direct Replacement","offer_id":63027241615731,"sku":"1177217-GEN","price":28.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63047956267379,"sku":"1177217","price":37.63,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1177217_57ae1438-8a82-4e23-9b09-8e6b0719468c.jpg?v=1782882763","url":"https:\/\/nationalhvacparts.com\/products\/icp-40va-transformer-for-wfml090b042b1-120v-to-24v-furnace-control-ships-today-1","provider":"National HVAC Parts","version":"1.0","type":"link"}