20 Most Recent Whirlpool MH7155XM Microwave Oven Questions & Answers

There is usually a 125V, 20 AMP line fuse inside the microwave, mounted at the point where the power cord enters the back of the unit. Unfortunately, you will need to uninstall the oven (if this is an over the range model), UNPLUG it and remove the exterior case to access. The case comes off in various ways depending on manufacture and model. If the model number you listed this question under is correct, you have THREE possibilties that may cause a complete loss of power: 1. Line fuse 2. The Oven Cavity Thermostat. 3. Thermal Cut-Out (Thermostat) for the Magnetron. The line fuse is connected in line with the power cord inside the unit and is listed as part of item 28 under the "Interior and Ventilation" parts heading. The thermostat for the oven cavity is listed as item 29 (part number 8183703) under the same parts heading. The thermostat for the Magnetron is listed as item 15 under the "Magnetron and Turntable Parts" heading. The part number is 8183698.

I would recommend you check the fuse, first. This the easiest and least expensive repair. It is also the most common. If you managed to overheat the oven any time recently, you may want to check the thermostat(s) to see if it is still good, next. They should read 0 ohms when measured out of the circuit across the terminals.

If the line fuse is blown, you can usually purchase a box of fuses at a hardware store for just a little more than what the manufacturer charges for a single fuse. 125V, 20AMP Ceramic Slow Blow fuses are recommended.

If you have any questions, or need additional assistance troubleshooting, please post back and let me know. I hope you find this information helpful. NOTE: Baked potatoes, steamed vegetables and popcorn are notrious for causing high humidity and/or overheat conditions in an oven cavity. If you find any of the thermostats tripped or blown, remember to allow the oven cavity to cool by leaving the door open between cooking items. This should only take a few minutes. Repeatedly heating items one after the other can cause high humidity and heat which may cause the thermostats to trip. Some of these thermostats reset themselves, others you need to replace.

NOTE: Make sure you take any resistance readings with the microwave UNPLUGGED and the component under test isolated (removed) from the circuit. These ovens can blow a fuse by simply sitting idle. This can occur from any power fluctuations, brown outs, voltage spikes, etc. Or, it could be the symptom of a component that may have failed. If you find the internal fuse blown and replace it, only to have it blow again, you have a more significant problem than a simple blown fuse.

Hi,
Here is a tip that will help you to figure out what is wrong with yourMicrowave Oven....

Microwave Oven Basic Troubleshooting Tips

heatman101

Hi,

Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Basic Microwave Oven Troubleshooting Tips

heatman101

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The magnetron may have either failed or is not being supplied with the extremely high voltage required to run it.
Make sure the !!!!capacitor is discharged!!!!! before attempting any sort of repair.
Check the door interlock switches first then the high voltage diode with either an AVO model 8 on high resistance range for short circuit, the feed fuse on the primary of the high voltage transformer and then finally, the magnetron is best checked by substitution.

If the magnetron has failed it is possible that it has taken out the mains fuse. Replace all faulty components with identical types and values!
Hope that helps.

Hello there:
If it It sounds normal,and seems to run ok but there's no heat When the microwave sounds okay, but there's no heat, one of the internal door switches, the high voltage circuitry, or the megatron or power inverter or the circuit board may have a problem. To resolve this problem, you need the assistance of a qualified appliance repair technician. ok hope this helps best regards mike

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Hello,

To replace the door handle you need to access the door handle screws. On MOST microwave ovens, you just have to remove the inner door panel that goes around the perimeter of the glass. This can be easily be accomplished by using a small screwdriver or putty knife and carefully insert along the seam of the inner panel and pry the plastic up. Work your way slowly around the perimiter of the glass to pop the panel loose. Use care not to pry against the glass. The glass is tempered and also has an RF shield that shields you from harmful RF radiation.

With the inner panel removed, the door handle screws are visibile and can easily be accessed with a screwdriver. Simply remove the broken handle and install the new one. Re-insert the inner door panel, gradually working your way around the perimeter of the door glass to ensure it snaps back into place and seats properly.

This repair can be done with the door in place, or you can remove it for easier access. If you decide the remove the door, open it all the way and lift straight up at the hinges. The door will lift off of the hinge pins. On some microwaves, you may have to remove the upper grill cover over the door (if equipped) to accommodate door removal. Place on a hard flat surface with some towels under it for padding. This protects the door facing from scatches.

NOTE: Some doors have a hinge pin that needs to be removed, or screws holding the door in place at the hinge.

You can view an exploded view diagram of your microwave at pcappliancerepair.com for reference. Just type in your model number and locate the parts listing for the door.

Take care.

There is a ceramic fuse inside the unit. You can order it from repairclinic.com. Use your model number to search for it. Sounds like your problem. Simply replace the fuse and you should be good. Remember to unplug the microwave before you open it up.

Let me know how this works out for you.
Benjamin

These machines seem prone to having a bad magnetron. Look for a circuit breaker near the power cord entry point. If tripped, reset and try to heat a cup of water. If it makes a loud buzz and then pops the breaker again, the consensus view is a bad magnetron. This is one repair that is recommended to send out. (~$150). You need to evaluate the probable cost vs a new machine.

This seems to be a defective magnetron tube. Because of the very high voltage, (~5000 volts) you need to be experienced in this type of repair. Sending it out for service may cost around $150, so you need to evaluate the probable cost vs a new oven.

Possibly a bird built a nest (swallows) in or on the roof vent. Make sure the fan turns freely when off. Check the vent tube that goes up to the roof--if flex-tubing, it may have collapsed and pinched off the air flow (it may be too long). Make sure that a one-way valve which should be near the exit of the hood is free to move when air flow pushes on it. This valve is supposed to prevent back-flow of air into the house. Hope this helps!

Does the internal blower run during cooking? This blower is located near the magnetron tube and is essential to the operation of this tube.

hi,the magetron is what heats the food...it has gone bad...or you have a burn mark on the cavity were you ,put the food in to heat up....please check the cavity first...next it will need to replace the magetron...hope this helps....

There is absolutely no way to guess at the problem. You need to troubleshoot the circuitry with a meter to find the failing component

you need to look at the ends on your fuse and this will tell you the amperage you need to get for your particular unit,get them from a hardware store

remove the outer cover and its in a fuse holder on the right side of unit get the right amperage