{"product_id":"tempstar-24v-transformer-for-t4h548gkb100-40va-control-transformer-ships-today","title":"Tempstar 24V Transformer for T4H548GKB100 — 40VA Control Transformer | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis OEM 24V control transformer for the Tempstar T4H548GKB100 steps line voltage down to the 24V needed to power the unit's low-voltage control circuit — the thermostat, contactor coil, reversing valve, and safety switches all rely on it. Rated at 40VA, it supplies enough current for the full control load. When a control transformer fails, the entire low-voltage circuit goes dead: the thermostat won't call, the contactor won't pull in, and the compressor and fan stay off even though high-voltage power is present. Transformers commonly fail from a shorted control wire, a shorted contactor coil, or age-related winding breakdown.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eNote:\u003c\/strong\u003e The associated part numbers 1172574 and 1175622 reference reversing-valve coil\/valve components on this model. Confirm the exact control-transformer part number against your unit before ordering.\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\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\u003eSecondary Voltage\u003c\/td\u003e\n\u003ctd\u003e24V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRating\u003c\/td\u003e\n\u003ctd\u003e40VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eHeat Pump Low-Voltage Control\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\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eFits the Tempstar T4H548GKB100 and related ICP-family outdoor units (Heil, Comfortmaker) using a 24V\/40VA control circuit. Verify primary voltage and VA rating against your existing transformer 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 disconnect and breaker, and verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the electrical access panel to reach the transformer and control board.\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 screws, and take out the failed transformer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, match primary leads to line voltage and secondary leads to the 24V circuit per your photos.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V across the secondary and that the thermostat call energizes the contactor.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eNo 24V at the control board or thermostat terminals\u003c\/li\u003e\n\u003cli\u003eContactor won't pull in on a cooling\/heating call\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage fuse or burnt-smelling transformer\u003c\/li\u003e\n\u003cli\u003eSystem has high voltage but no control-circuit operation\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\u003cp\u003eShips same day on orders placed before 3 PM CST. 30-day returns on unused parts. Backed by the National HVAC Parts fitment guarantee.\u003c\/p\u003e","brand":"Tempstar","offers":[{"title":"Direct Replacement","offer_id":63021782270323,"sku":"1172574-GEN","price":29.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048397619571,"sku":"1172574","price":37.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172574_d3ab2b01-297d-41bd-ba29-c95cf78b06e1.jpg?v=1782958083","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-24v-transformer-for-t4h548gkb100-40va-control-transformer-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}