The 5840 has a problem with dust getting on the heater element and turning itself off after 2 minutes running. HERE IS THE FIX. Unplug the unit from the AC outlet, Then using a can of dusting air ( the kind you use to clean a computer key board) aim the compressed air INTO the middle louver of the upper adjustable heater vent and blow out the dust that has gotten on the heater element. ( You are actually blowing into the unit, clearing off the lint/dust that has gotten on the backside of the heater element that you can not see without openning the entire case).You can see the front of the heater element inside the louvers, It's the shinny metal part that looks like a small radiator.It sits behind the middle louver. After blowing out the dust, shake the entire unit to allow the dust to settle to the bottom of the case. Using a vacum cleaner try to vacum out any dust from the LOWER FRONT intake. Once the dust has been blown OFF the heater element, the unit will work just as new and not shut itself down!
Cleaning did not work for me, but this is the best option if it works. Definitely try that first. I cleaned the mesh filter at bottom of front of heater, blew air through element as recommended above, still shut down regularly except when used in very cold room, then it stayed on. I thought it might be an air flow problem, as restrictive flow could cause heat to build up. I cut a square hole, approx 3" by 3" in middle back of unit, no shut downs since. I suppose you could tape a filter over hole if you like, I left it open. I think the mesh filter at bottom front doesn't allow enough air in, could cause a higher running temp.
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Connect the test leads to your DMM. Insert the black lead in
the black "common" socket and push the red lead in the red socket
labeled "volts, ohms, milliamperes." Set the function switch on your DMM
to the "ohms" function.
Use a Phillips head screwdriver to remove the space heater's
back cover and disconnect the power cord from the switch and heating
Check the power cord for a broken wire. Touch one test probe
to first one blade, then the other blade on the plug and then touch the
other probe to the other end of the power cord. If the wire is working,
there should be an indication of 0.00 to 0.5 ohms between each blade on
the plug and a different end of the power cord. If the meter indicates
"O.L." on one or both sides of the cord, the wire is defective. Most
often, the wire will be broken right at the molded plug or inside the
plug. The easiest way to fix this problem is to replace the cord set.
Check between the two sides of the power cord for a 0.00 to
0.5 ohms reading indicating a short between the two sides of the line
cord. If the heater tripped a circuit breaker, there is a short circuit
somewhere in the heater wiring. Shorts in a power cord usually occur
inside the molded plug. The short could be inside the cord set, if it
has been pinched or cut. Fix by replacing the cord set.
Check the thermostatic switch by placing one test probe on
each of the switch terminals. Turn the switch slowly through its
complete range. The DMM should indicate a continuous 0.00 to 0.5 ohms
throughout the switch's full range of movement. An "O.L." indication
here indicates a faulty switch, and you need to replace it. The reason
that a functional switch could read 0.5 ohms and not 0.00 ohms is that
some DMMs read their internal fuse's resistance.
Check the heating element for an open circuit or short
circuit. A typical radiant heating element will have a resistance of
roughly 15 to 30 ohms. A burned out heating element will read "O.L." and
need to be replaced. A reading significantly lower than 15 ohms
indicates a shorted or partially shorted heating element, and it needs
to be replaced.
Reconnect the wires that you disconnected earlier and plug
the heater in. Check the blower motor voltage if the heating element
gets hot but the fan does not work. This is the only test that you will
have to make with the heater plugged in, so use caution here.
Set the DMM for "AC volts" and touch the test probes to the
motor leads. A reading of 115 volts here indicates a defective fan
motor, and you need to replace it.
Replace pressure switch. If you blow any air into the pressure switch it has been damaged,check air ports for debris by looking never ,never blow on air switch they work on a very small pressure or vaccum,where your breath is to much pressure and also loaded with unwanted humidity.
I want you to do a simple test to verify that this is a thermostat problem for me. Start by removing the thermostat from its' mounting, next locate the red and white wire terminals place a jumper between them. If the heater now runs it is the thermostat went bad on you, if it does not run please check all connections both to the thermostat and to the furnace making sure that your wires have tight connections and are not broken. I am really leaning towards the thermostat being bad here. Sorry for the bad news but really strong feeling. Good luck
Solid red typically means bad controller. Try unplugging the furnace, wait about 30 secs, then plug it back in. The possibility that the controller was sending voltage to the valve even when there was no flame is a bad sign. If the controller starts the furnace, watch it very closely and see what it does. If the solid light comes back on, it's time for a new board.
not knowing wich one is on, this red light could be your power indicator light..
it stays on during any operation,
you should be able to see it through the sight glass
if it were flashing,,,, there would be a problem