Atwood 8940 Iii Dclp Troubleshooting
Atwood furnace flashing a code-3 blinking lights « on: May 29, 2009, 09:16:55 pm » We took our 02 Coleman Westlake to the dealer to be looked at for the flashing a red light code on the furnace's control board- blinking 3 times then stops, blinks again for 3 times, etc.
Website MenuTroubleshooting theRV DSI FurnaceThe following descriptions are based on the Hydro Flame 8500 series furnaces, but theoperating principles are similar for other manufacturers.Low battery voltageThe furnace is designed to operate at voltages between 10.5 to 13.5 VDC. Low voltage will not run the blowermotor at the proper speed to commence the ignition sequence.Obstructed return air intakeReturn air is the air that flows in to replace the heated air that the blower pushes out through the ducting.This air is pulled in by the furnace through louvered openings in the side of the furnace cabinet, and any itemsstored near these openings could interfere with this air flow.
More information on this.Obstructed exhaustThe exhaust venting must be clear of all obstructions for proper furnace operation. Inspect the vents for insector bird nests or other debris.Low gas pressurePlease see the for more information and a simple manometer you canbuild yourself!Time delay relayThis relay performs two separate jobs - one to handle the relatively high current needed to run the blower motor- and two, to allow the blower to run for 45 to 90 seconds after the thermostat is satisfied. This allows excessheat in the chamber to dissipate before the blower stops.The relay is normally open and should always have power from the circuit breaker. Only when power from thethermostat is present does the relay close after a 20 second delay. Power then flows to the blower motor.Blower motorNext in the ignition sequence is the blower motor. It drives two squirrel cage fans to provide separate air flowfor the combustion process and for distributing the heated air to the coach.
Atwood 8940 Iii Dclp Troubleshooting System
A heat exchanger is used to separatethe heat from the burning gas while preventing exhaust gases from entering the living space.Specific motors are used in each model and BTU size of furnace and the correct replacement motor must beused.Sail switchThe sail switch is an on/off device. (normally in the off position) It gets it's name from the 'sail' or paddlethat is attached to the switch mechanism. As the blower comes up to speed, it blows air onto the sail with enoughforce to push the switch closed, thus allowing electrical current to flow to the next component in line.It's job is to determine if there is adequate air flow for proper combustion to take place.
If the batteryvoltage is low or the fan does not come up to 75 per cent of it's design speed, the sail switch will not close.Possible causes of this malfunction are: low battery, restricted return air inflow, restricted or inadequateoutlet vents, restricted combustion air inlet or exhaust, faulty sail switch.Limit switchThe limit switch is a simple temperature controlled switch. It's function is to monitor the combustion chamberheat level. If the temperature of the combustion chamber exceeds the preset limit, the switch will open and disruptthe flow of current to the circuit board, in effect, shutting down the main burner. Once the chamber temperaturecools sufficiently, the limit switch resets.
Atwood 8940 Furnace Parts List
This initializes the ignition sequence and starts another cycle.