{"product_id":"tempstar-defrost-control-board-for-t4h448gkb100-oem-1173636-ships-today","title":"Tempstar Defrost Control Board for T4H448GKB100 — OEM 1173636 | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is the OEM defrost control board (part number 1173636) for the Tempstar T4H448GKB100 heat pump. The defrost control board is the brain of the heat pump's defrost cycle — it monitors outdoor coil temperature and run time, then commands the reversing valve, auxiliary heat, and outdoor fan to clear frost from the coil during cold-weather operation. When this board fails, the unit cannot defrost properly, leading to ice buildup on the outdoor coil, reduced heating capacity, short cycling, or a heat pump that locks out entirely. Replacing it with the genuine OEM board restores correct defrost timing and protects the compressor.\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\u003eFits Model\u003c\/td\u003e\n\u003ctd\u003eT4H448GKB100\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 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 T4H448GKB100 heat pump. The same board is shared across many ICP-family (Tempstar \/ Heil \/ Comfortmaker) heat pumps of this series — always confirm your existing board's part number 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 outdoor disconnect and verify zero voltage with a multimeter before touching any wiring.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the control panel access cover on the outdoor unit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every wire and terminal 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 sensor leads, then unclip or unscrew the failed board from its standoffs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new 1173636 board, reconnect each wire exactly per your photo, and seat the defrost sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm the unit runs in heat mode and initiates a normal defrost cycle.\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 clears during heating\u003c\/li\u003e\n\u003cli\u003eHeat pump short cycles or won't switch out of defrost\u003c\/li\u003e\n\u003cli\u003eAuxiliary\/emergency heat runs constantly\u003c\/li\u003e\n\u003cli\u003eNo 24V output to the reversing valve or outdoor fan\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":63021784727923,"sku":"1173636-GEN","price":129.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048445264243,"sku":"1173636","price":168.94,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-control-board-defrost-1173636_dca46659-b44d-4cbb-8b9a-c6170ac514eb.jpg?v=1782959860","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-defrost-control-board-for-t4h448gkb100-oem-1173636-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}