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I have a Noma brand heater model: AFH302OTW. I recently disassembled the housing to vacuum all the dust inside that had accumulated over many years. After I reassembled the housing, a problem occurred. The heater would run for a short period of time, then a spark would occur next to the heating coil and the unit shuts off on its own. The fan is working and there is heat from the heating coil before it shuts down. If I unplug the unit and let it cool, it would turn on again for a short while until it shuts off again. I presume something is overloaded that is causing the safety switch to kick in, but I am puzzled which part failed. Could it be a faulty temperature sensor?
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Hi, Here is an image taken from one of your images. ;-)
(click on image to enlarge for better viewing) Just so there is a better view, if you can, by using a soft brush could you please clean the area in the red circle? (power disconnected of course) Also is the heater element wire shown by the green arrow actually touching the metal strip below? It seems very close. If it is I don’t think that it should be. The connection shown in the yellow square, is it a dry joint wire? I don’t particularly like seeing ‘holes’ when a wire is supposed to be terminated correctly
Eddie Yeung this sounds like your limit thermostat is turning of the unit. Post some images of it disassembled so we can see what you see. Use this guide Adding images to an existing question for that Update (03/17/2018) Eddie Yeung looks like the diodes (Zener diodes as well) have failed. Those are most likely part of the rectifier circuit for your heater. The only way to fix that would be by carefully desoldering those and take a look at them to identify which diodes these are. Again, do feel free to add images of those if you are having trouble identifying them. On the same image that @jayeff pointed out, can you identify that there is a resistor or similar between the contacts?
