{"product_id":"tempstar-defrost-control-board-for-t4h318gka100-heat-pump-timer-board-ships-today","title":"Tempstar Defrost Control Board for T4H318GKA100 — Heat Pump Timer Board | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis genuine OEM defrost control board (Tempstar part 1173636) is the brain of the heat pump's defrost cycle. In heating mode the outdoor coil collects frost; the defrost board monitors the defrost thermostat and a timing interval, then briefly reverses the valve and shuts off the outdoor fan to melt accumulated ice before returning to heat. A failed defrost board leaves the outdoor coil iced over, kills heating capacity, and can trip the system on high head pressure. Typical failure symptoms include a coil that ices up solid in winter, defrost cycles that never run or run constantly, the auxiliary heat staying engaged, or the outdoor fan behaving erratically.\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 family)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eControl Voltage\u003c\/td\u003e\n\u003ctd\u003e24V Logic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFunction\u003c\/td\u003e\n\u003ctd\u003eDefrost Timing, Reversing Valve \u0026amp; Fan Control\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-fit replacement for the Tempstar T4H318GKA100 heat pump and shared-platform ICP, Heil, and Comfortmaker outdoor units that use the same defrost control board. Match the board part number and connector layout 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, then verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the condenser control-box panel to reach the board.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every plug and wire location before unplugging anything.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the harness plugs and low-voltage leads, then unclip or unscrew the board from its standoffs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new board, reseat each connector firmly, and confirm the defrost timing pins match the old board.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, run a heating call, and verify normal operation and a forced defrost if accessible.\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 stays frozen in heating mode.\u003c\/li\u003e\n\u003cli\u003eDefrost cycle never initiates or runs continuously.\u003c\/li\u003e\n\u003cli\u003eAuxiliary\/emergency heat runs constantly.\u003c\/li\u003e\n\u003cli\u003eOutdoor fan or reversing valve behaves erratically during heat.\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":63021803209075,"sku":"1173636-GEN","price":119.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048440152435,"sku":"1173636","price":154.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-control-board-defrost-1173636_5fa5e9b4-4fd8-48e7-87e2-dcd03ed3c4e1.jpg?v=1782959681","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-defrost-control-board-for-t4h318gka100-heat-pump-timer-board-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}