Suddenly our microwave oven constantly runs with the interior light on and the internal fan, but does not heat anything. It also does not turn off unless you open the door and does not allow you to use any other functions on the botton display, especially the start botton. We've un-plugged the unit but don't know what is wrong with it. It was working just fine. I used it to cook rice for 30 min. When the rice was finished cooking the timer went off. A few minutes later it began running as described above and would not turn off, unless you opened the door. As soon as you close the door the fan would run and the light stays on continuosly, unless you unplug the unit.
I have the R-1460 in the same series with the identical symptoms. After reading MicrowaveSvc's solution I started taking apart to view the door switches and found the upper door switch to be the problem, but not a switch failure a support failure. A small bottom plastic support post that holds the switch in place was broken (probably from repeated use/abuse) allowing the switch to move when the door hooks were engaged, thus not actuating the button switch. Since the problem was mechanical rather than an electrical bad switch, I made a small support arm for the switch from an old plastic mechanical pencil and glued it in place to hold the switch in its correct position. Problem solved, microwave works! Thanks to MicrowaveSvc's description of door switches.
Hey Poo, this almost sounds like a key-pad issue. If the oven is starting on it's own it sounds like you have a shorted or stuck key pad. When you open the door the primary and secondary switches open and the monitor switch closes. If the monitor switch finds one of the others closed when the door is opened, it would blow the internal fuse. One way you would be able to tell for sure is to remove the key pad ribbon cable from the main control board. If the oven does not start by itself, you know you nailed the problem. Be carefull, this is high voltage in there and should be done by someone who is qualified. Catriver...post back
Sounds like you have a shorted triac device inside the microwave. Very common problem. This is not a replaceable item for the user to replace.Looking at the age and the make of this microwave,it way be time to purchace a new oven ? Good Luck
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