{"product_id":"tempstar-defrost-control-board-for-t4h448gkc100-24v-heat-pump-control-ships-today","title":"Tempstar Defrost Control Board for T4H448GKC100 — 24V Heat Pump Control | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is the OEM defrost control board (part number 1173636) for the Tempstar T4H448GKC100 heat pump. The defrost control board governs the unit's defrost cycle — monitoring outdoor coil temperature and run time to decide when to melt accumulated frost and ice during heating. It also sequences the reversing valve, compressor, and auxiliary heat. A failed board commonly causes a frozen outdoor coil, a heat pump stuck in one mode, short-cycling, or a unit that ignores the thermostat. This direct-fit 24V OEM replacement restores factory-correct defrost timing and system control.\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 (ICP \/ Heil)\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\u003eFitment\u003c\/td\u003e\n\u003ctd\u003eOEM, model-specific\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFor Model\u003c\/td\u003e\n\u003ctd\u003eT4H448GKC100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eEngineered for the Tempstar T4H448GKC100 heat pump and shared across ICP-family condensing units (Heil, Comfortmaker, Tempstar) that originally used board 1173636. Confirm the OEM number on your existing board before ordering.\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, then verify zero voltage at the board with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the control-panel service cover on the outdoor unit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every wire and connector position before disconnecting anything.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and unplug the low-voltage harness and sensor leads, release the standoffs, and lift out the old board.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Seat the new board on the standoffs and reconnect every lead exactly as photographed, including the defrost sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, run a heating cycle, and confirm defrost initiates and terminates correctly.\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 defrosts\u003c\/li\u003e\n\u003cli\u003eHeat pump won't switch between heating and cooling\u003c\/li\u003e\n\u003cli\u003eCompressor short-cycles or runs nonstop\u003c\/li\u003e\n\u003cli\u003eNo 24V output to the reversing valve or contactor\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":63021784334707,"sku":"1173636-GEN","price":135.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048445460851,"sku":"1173636","price":175.5,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-control-board-defrost-1173636_95421e39-442b-482f-adc8-ecadc5afc960.jpg?v=1782959864","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-defrost-control-board-for-t4h448gkc100-24v-heat-pump-control-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}