{"product_id":"arcoaire-40va-transformer-208-240v-to-24v-for-ag100-ag250-series-ships-today","title":"Arcoaire 40VA Transformer 208\/240V to 24V for AG100–AG250 Series — Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThe Arcoaire 79471 (OEM cross AT72H1002) is a 40VA control transformer that steps 208\/240V line voltage down to 24V to power the furnace control board, gas valve, and thermostat circuit across the AG series. The transformer supplies every low-voltage control component — when it opens or shorts, the furnace loses all 24V power and will not start, leaving the thermostat dark and the system unresponsive. The typical failure is a shorted secondary from a grounded control wire that overheats and burns out the windings. A correctly rated 40VA OEM replacement restores reliable control-voltage power and proper furnace operation.\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\u003e79471\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOEM Cross\u003c\/td\u003e\n\u003ctd\u003eAT72H1002\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\u003eArcoaire (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\u003e208 \/ 240V\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\u003eFits Models\u003c\/td\u003e\n\u003ctd\u003eAG100, AG130, AG170, AG200, AG250\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eDirect OEM replacement for Arcoaire AG100, AG130, AG170, AG200, and AG250 furnaces. Verify your primary voltage tap and VA rating 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 at the furnace switch 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 all primary and secondary leads before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the leads, remove the mounting hardware, and pull the old transformer. Check the low-voltage wiring for shorts before energizing the replacement.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, land the primary on the 208 or 240V tap to match your supply, and reconnect the 24V secondary per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, confirm 24V at the secondary with a multimeter, and verify the controls energize on a call.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eFurnace completely dead with no 24V control power\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage control fuse\u003c\/li\u003e\n\u003cli\u003eOverheated, buzzing, or discolored transformer\u003c\/li\u003e\n\u003cli\u003eNo measurable voltage at the secondary terminals\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":"Arcoaire","offers":[{"title":"OEM","offer_id":63027184304499,"sku":"79471","price":44.2,"currency_code":"USD","in_stock":true},{"title":"Generic","offer_id":63047208337779,"sku":"79471-GEN","price":34.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-79471.jpg?v=1782877342","url":"https:\/\/nationalhvacparts.com\/products\/arcoaire-40va-transformer-208-240v-to-24v-for-ag100-ag250-series-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}