{"product_id":"tempstar-defrost-control-board-for-t4h318gkd100-heat-pump-timed-demand-defrost-ships-today","title":"Tempstar Defrost Control Board for T4H318GKD100 — Heat Pump Timed\/Demand Defrost | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThe OEM defrost control board (part #1173636) is the brain of the defrost cycle on your Tempstar T4H318GKD100 heat pump. It monitors coil temperature and accumulated run time, then commands the reversing valve, outdoor fan, and auxiliary heat to clear frost from the outdoor coil during cold weather. A failed board is one of the most common causes of a heat pump that ices over, fails to defrost, won't switch between heating and cooling, or short-cycles. The board operates on a 24V control signal and integrates the defrost sensor, timer logic, and relay outputs into a single replaceable assembly.\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\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eHeat Pump Outdoor Unit\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFunction\u003c\/td\u003e\n\u003ctd\u003eTimed \/ demand defrost control\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eDesigned as the factory replacement for the Tempstar T4H318GKD100 heat pump condenser. This board is shared across many ICP-family heat pumps (Tempstar, Heil, Comfortmaker, Arcoaire) of the same vintage — verify the original part number 1173636 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 outdoor disconnect and verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the control panel cover from the condensing unit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every wire and terminal position before disconnecting anything.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and unplug the low-voltage connectors and sensor leads, then unscrew the old board from its standoffs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new board, reconnect each wire exactly per your photos, and seat the defrost sensor on the coil.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and force a defrost test to confirm the reversing valve and fan respond correctly.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eOutdoor unit ices over and never defrosts\u003c\/li\u003e\n\u003cli\u003eHeat pump won't switch between heating and cooling modes\u003c\/li\u003e\n\u003cli\u003eNo 24V output to the reversing valve or contactor\u003c\/li\u003e\n\u003cli\u003eVisible burn marks, corrosion, or scorched relays on the board\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":63021803078003,"sku":"1173636-GEN","price":149.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048440283507,"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_9df600fb-380d-4f98-8d36-ec671a45eb80.jpg?v=1782959686","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-defrost-control-board-for-t4h318gkd100-heat-pump-timed-demand-defrost-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}