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4.5
Our 26-year old Payne furnace recently experienced failure of the Solid State Time Delay Relay during a power brownout. Despite our efforts to quickly shut off the AC and pull the plug on the furnace, the damage to the HH84AA009 fan control board was already done. While several websites offer more expensive products that claim to be original replacements, a quick glance at site photos reveals that they are not. Everything available differs substantially from the original board. Hence, I chose this less expensive replacement part. Furthermore, this same board fits a broad range of different furnace brands.Fortunately, the manufacturer's website (http://www.icmcontrols.com/Fan-Blower-Control-replacement-for-OEM-models-including-Carrier-CES0110019-and-HH84AAx-series-control-boards-Prodview.html) has the installation instructions with wiring diagrams so you can study the product in detail before deciding to purchase it.The only issue I encountered in the installation instructions concerned the resistor R18. For some installations the lead(s) to this resistor should be cut, for others (including mine) it should not. So, how does one determine whether to cut or not? If all else fails, try installing the board without cutting and if that fails to work properly, cut R18. If you would like to take the proper action with R18 before installing, you need to study how your thermostat works. For natural gas furnaces, thermostats simply connect the 24 VAC supplied by the furnace on terminal "R" to the the controller's terminal "W" to start the burner and the blower. For air conditioning, there are two possible methods used by thermostats. If the "intelligence" is in the thermostat, then it will connect "R" to "Y" which turns on the compressor unit; Simultaneously, the thermostat connects terminal "R" to "G" to energize the blower. Other thermostats let the fan controller board (ICM275) provide the "intelligence" and the thermostat only connects "R" to "Y", relying on the fan controller to detect this and simultaneously energize the blower. For this second case, "intelligence" provided by ICM275, you should cut the lead(s) to R18.
