{"product_id":"tempstar-comfortalert-control-board-for-t4a418gkd100-diagnostic-module-ships-today","title":"Tempstar ComfortAlert Control Board for T4A418GKD100 — Diagnostic Module | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis is a genuine OEM ComfortAlert diagnostic control board (OEM part number 1177402) for the Tempstar T4A418GKD100 condensing unit. The ComfortAlert module continuously monitors compressor and system operation — voltage, current, run\/lock-out cycles — and reports faults through a flashing LED code, giving technicians fast, accurate diagnostics without back-and-forth troubleshooting. It also provides protective lock-out logic that guards the compressor against conditions like low voltage, locked rotor, open circuit, and short cycling. Common failure symptoms include no LED activity, false or stuck fault codes, a compressor that won't energize, or erratic system lock-outs. Replacing a failed board restores accurate diagnostics and full compressor protection.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\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\u003eOEM Part Number\u003c\/td\u003e\n\u003ctd\u003e1177402\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eComfortAlert Diagnostic 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\u003eControl Voltage\u003c\/td\u003e\n\u003ctd\u003e24 V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFunction\u003c\/td\u003e\n\u003ctd\u003eCompressor monitoring, fault-code diagnostics, protective lock-out\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFits Model\u003c\/td\u003e\n\u003ctd\u003eT4A418GKD100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cp\u003eEngineered as a direct-fit replacement for the Tempstar T4A418GKD100 air conditioner. This OEM ComfortAlert board is also used across many ICP\/Heil\/Tempstar\/Comfortmaker units that call for part 1177402. Confirm your unit specifies the ComfortAlert diagnostic module before installing.\u003c\/p\u003e\n\n\u003ch3\u003eInstallation Guide\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety First\u003c\/strong\u003e — Disconnect power at the outdoor disconnect and the breaker, then verify zero voltage at the board terminals with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the service panel from the condensing unit to expose the control board.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every low-voltage and sensing lead landed on the board before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the wiring, release the board from its standoffs or mounting screws, and lift it out.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new ComfortAlert board, reconnect each lead to the matching terminal per your photo, and seat all connectors fully.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, call for cooling, and confirm the LED shows normal operation with no active fault codes and the compressor energizes correctly.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eDiagnostic LED is dark or unresponsive on power-up.\u003c\/li\u003e\n\u003cli\u003eFalse, stuck, or constantly repeating fault codes.\u003c\/li\u003e\n\u003cli\u003eCompressor will not start or repeatedly locks out without cause.\u003c\/li\u003e\n\u003cli\u003eErratic short-cycling or loss of compressor protection.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\n\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":63021806584179,"sku":"1177402-GEN","price":189.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048417673587,"sku":"1177402","price":246.94,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-control-board-furnace-1177402_d42db528-4748-47a3-80c7-ad45d305aed3.jpg?v=1782958700","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-comfortalert-control-board-for-t4a418gkd100-diagnostic-module-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}