{"product_id":"tempstar-defrost-control-board-for-t4h548gkb100-oem-1173636-heat-pump-board-ships-today","title":"Tempstar Defrost Control Board for T4H548GKB100 — OEM 1173636 Heat Pump Board | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is a genuine OEM defrost control board (part number 1173636) for the Tempstar T4H548GKB100 heat pump. The defrost control board manages the heat pump's defrost cycle — it monitors outdoor coil temperature and accumulated run time, then initiates a defrost to clear frost and ice from the outdoor coil during winter heating. It coordinates the reversing valve, outdoor fan, and auxiliary heat to maintain efficient operation in cold conditions. A failed board can leave the coil iced over, stuck in defrost, short-cycling, or unable to heat. The board runs on a 24V control circuit and carries the standard Tempstar heat pump defrost timing logic.\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\u003e1173636\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eDefrost Control Board\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\u003eControl Voltage\u003c\/td\u003e\n\u003ctd\u003e24V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eHeat Pump Outdoor Unit\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\u003eDirect OEM fit for the Tempstar T4H548GKB100 heat pump and shared across related ICP-family outdoor units (Heil, Comfortmaker, and other Tempstar models) using the same defrost control platform. Confirm your existing board reads 1173636 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 before handling wiring.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the outdoor unit's electrical access panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every wire and connector on the existing board first.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and unplug the harnesses, remove the mounting screws, and lift out the old board.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new 1173636 board, reconnect each harness exactly per your photos, and seat all connectors fully.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, confirm the unit heats, and force a defrost cycle to verify the board commands the reversing valve and fan.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eOutdoor coil ices over and never enters defrost\u003c\/li\u003e\n\u003cli\u003eUnit gets stuck in defrost and won't return to heating\u003c\/li\u003e\n\u003cli\u003eNo 24V output to the reversing valve or outdoor fan\u003c\/li\u003e\n\u003cli\u003eScorched relays, corrosion, or burn marks on the board\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":63021782368627,"sku":"1173636-GEN","price":149.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048446706035,"sku":"1173636","price":193.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-control-board-defrost-1173636_b60cadd4-9905-424b-9f47-47127a53125e.jpg?v=1782959906","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-defrost-control-board-for-t4h548gkb100-oem-1173636-heat-pump-board-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}