{"product_id":"tempstar-defrost-control-board-for-t4h324gkd300-oem-1173636-ships-today","title":"Tempstar Defrost Control Board for T4H324GKD300 — OEM 1173636 | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThe OEM defrost control board (part number 1173636) is the logic center that manages the defrost cycle on your Tempstar T4H324GKD300 heat pump. During heating mode, frost and ice accumulate on the outdoor coil; this board monitors elapsed run time and coil temperature, then commands a timed defrost cycle—reversing the refrigerant flow and energizing the auxiliary heat—to melt that ice and restore efficiency. When the board fails, the system can no longer initiate or terminate defrost correctly, which leads to a coil that ices over solid, sharply reduced heating output, a unit that runs constantly, or one that never defrosts at all. A failed board is one of the most common causes of a heat pump that \"won't heat\" in cold weather.\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\u003eFunction\u003c\/td\u003e\n\u003ctd\u003eDefrost cycle timing \u0026amp; control\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFitment\u003c\/td\u003e\n\u003ctd\u003eOEM Replacement\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eThis control board is the factory-specified replacement for the Tempstar T4H324GKD300 heat pump. Because ICP, Heil, Comfortmaker, and Tempstar share platforms, it also serves as the OEM board on closely related models in the same family. Always confirm your existing board's part number 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 with a multimeter before touching any wiring.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the outdoor unit's control-panel service cover.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every wire and terminal connection on the existing board before disconnecting anything.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and disconnect the low-voltage and line-voltage leads, release the mounting 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 each wire exactly as photographed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and verify the unit initiates and terminates a defrost cycle normally.\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 the unit never defrosts\u003c\/li\u003e\n\u003cli\u003eHeat pump runs continuously but delivers little or no heat\u003c\/li\u003e\n\u003cli\u003eDefrost cycle runs too often or won't terminate\u003c\/li\u003e\n\u003cli\u003eAuxiliary\/emergency heat never engages during defrost\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":63021800849779,"sku":"1173636-GEN","price":109.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048440676723,"sku":"1173636","price":141.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-control-board-defrost-1173636_aa128fab-5baf-4f5c-a71a-33bcb4b3173b.jpg?v=1782959701","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-defrost-control-board-for-t4h324gkd300-oem-1173636-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}