{"product_id":"tempstar-40va-transformer-for-thb09k34rta-208-240v-to-24v-oem-ships-today","title":"Tempstar 40VA Transformer for THB09K34RTA — 208\/240V to 24V OEM | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is a genuine OEM 40VA control transformer assembly for the Tempstar THB09K34RTA PTAC unit, supplied with its associated 24V relays. The transformer (OEM part 1056899) steps line voltage of 208\/240V down to the 24V control voltage that powers the thermostat, relays, and contactor circuit. It is paired here with a 24V relay (1053004) and a 24V DPST relay (1060940) that switch the unit's heating and cooling loads. When a transformer fails — typically from a shorted secondary or overload — the entire low-voltage control circuit goes dead and the unit will not respond to any command, even though line power is present.\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\u003e1056899 (transformer), 1053004 \/ 1060940 (relays)\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\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\u003eVoltage\u003c\/td\u003e\n\u003ctd\u003e208\/240V primary, 24V secondary\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelays\u003c\/td\u003e\n\u003ctd\u003e24V SPST + 24V DPST\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFits Model\u003c\/td\u003e\n\u003ctd\u003eTHB09K34RTA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eThis 40VA transformer and relay set is the factory-specified control-power components for the Tempstar\/Heil\/ICP THB09K34RTA PTAC model and installs as a direct OEM replacement.\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 unit and breaker, then verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the PTAC front cover and electrical control panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph all primary and secondary wire connections before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the transformer leads, note primary tap selection, and unbolt the transformer and relays from the chassis.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and relays, matching the correct primary voltage tap, and reconnect wiring per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V at the secondary and proper relay operation.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eEntire low-voltage control circuit is dead with line power present.\u003c\/li\u003e\n\u003cli\u003eNo 24V reading at the transformer secondary terminals.\u003c\/li\u003e\n\u003cli\u003eVisible scorching, melted housing, or a burnt smell.\u003c\/li\u003e\n\u003cli\u003eRelays chatter, fail to pull in, or will not energize.\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":63021638517107,"sku":"1053004-GEN","price":32.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048412561779,"sku":"1053004","price":41.6,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1053004_854a653e-550b-48da-bc6a-b4caf762d673.jpg?v=1782958597","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-thb09k34rta-208-240v-to-24v-oem-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}