I have a Hobart AM-14 dishwasher that won't
Ok, Dont forget to disconnect the power before touching anything electrical. especially around water!. Much of what I've added here will take care of most motor issues and doesnt necessarilly pertain to the problem that this guy had. I just added the extra tips for those of you having similar problems with am12 or am14 dishwashers.
Always check and repair burnt wires if needed.
1st: With the power on! Look at the main control board inside control panel door. make sure the Hot Motor Light is Not illuminated. If it is, you have a hot motor or one of the two sensors in the motor is open(bad, no resistance). With the power off, Motor Sensors can be bypassed with 1000ohm resistor from Radio Shack. Hobart does sell the sensors (motor thermistors). They have to be packed into the motor windings by a motor specialist to replace them. Otherwise just bypass the one that is bad by rigging resistor into the plug where the "sensors" wiring harness plugs into the board or rig it into the motor side of harness and tape it up so it doesn't short out to anything. Note: A bad contactor on 3 phase units can cause over heating(usually you will hear motor hum). On single phase motors, a bad start switch(inside motor) or capacitor(mounted on motor)
will stall the motor and overheat(again you may hear it hum, usually). IF YOUR MOTOR HUMS, The FIRST thing to check is to make sure the motor spins freely. take a screw driver or something similar and try to spin the motor by pushing on the plastic fan visible thru motor vents. If it does not spin freely, check to make sure there is no silverware or a scratch pad stuck in suction side of pump, inside dishwasher tank. Its tough to get to, you may feel it with your fingers or use a small mirror and flash light to see up under the inlet hood thingy. if its clear, You may have bad motor bearings. Remember, thats if the motor does not spin.
2nd: Check for blown slowblo fuses on main control board iinside of control panel door. Check all the fuses for that matter. There are 4 or 5 total depending on what version you have. Most likely it is one of the fuses on the control board. Some times its hard to tell by looking at the fuse if it is bad or not. Check it with ohm meter or swap it out with correct fuse. Also there are small lights that are labeled on this board. One is for the door switch. With door closed it should be lit. Open door, no light. If that light is working correctly, and you dont have a hot motor as in step one and your fuses are good, you either have a bad contactor coil or bad motor. OR The control board itself is bad (unlikely, but possible) but make sure you check all the other possibilities first before you go replacing the expensive parts (motor or control board).
Tips: Make sure there is no water dripping into any of the electrical boxes or componants. This may be blowing fuses. I usually use 1 1/2 amp sloblow fuses on the "control boards". Check the wiring diagram in control panel to verify what size is intended to be in it. If it doesnt say, use what I use.
If your going to Rewind motors locally at a fraction of cost of new. *If you have bad motor thermistors*, buy new ones from hobart. The guys I deal with at the motor place I use, made the mistake of thinking the sensors where thermal fuses and thought they were bad. No, these are thermistors and as long as you measure some resistance in them, say over 900ohms, they should be good. Most all of the bad thermistors I've seen, measure Open (no resistance). sometimes they gradually go out and give you fits trying to figure out where the problem is, as far as the hot motor light goes.
on Jun 23, 2018