Thread: over range whirlpool microwave

It could be as simple as an interlock switch or possibly a magnetron that has failed. Since the display is working, each of the safety fuses are working, so now it's down to making sure voltage is getting to the high voltage section and then doing some diagnosing of the related components. This type of troubleshooting will require the unit to be removed from the wall and the cabinet removed to gain access to the related components.

Some things to consider. This is not to difficult to diagnose, but the components can be hard to get to. Microwave ovens use very high voltages, some of which can still be present even when the oven is unplugged so it is very important to be comfortable using a multimeter and working around electricity. The high voltage capacitor must be discharged before attempting any work on the high voltage section. The likely failure is a magnetron which may be under a 5 year warranty so something to check on before turning any screws yourself.

If you feel you have the skills and the tools, I can provide some advice to help with your repair.

Originally Posted by bmadsen

HI I have a fairly new microwave ive had less than two got it brand new model-MH2175XSB - 2 it turns on and table turns but there is no heat I figure its a fuse or something but have no idea where to start any ideas???

When you try to microwave, is it either quieter or louder than normal?

We have a sound clip of what a microwave should sound like when the cooling fan and high voltage section are operating here.

Have you ever noticed an "F6" error in the display?

That kind of problem really needs a tech to look at it. If everything sounds normal, meaning the magnetron is growling, it could be just a diode. It's been my way to replace all 3 hi voltage components, mag/cap/diode, because 4000v runs thru that circuit and when one goes I wouldn't trust the other 2. It's not a fuse or tco(one shot thermostat) because the display would be dead. The first thing I would do is verify power from the main board to the transformer or inverter board, depending on which this model uses. If there is 120v to the inverter/transformer, you know you have a hi voltage problem.

I'm sure this has been dealt with by now, but here's some more advice for the next guy.

He said it was fairly new. If it's under warranty, call the manufacturer at the number listed in your owner's manual (which you should never throw away!) so you can get it fixed free.

In this case, the turntable turned but there was no heat.

Looking at the technical sheet found inside the microwave or online here, we can see pretty quickly that in this case, the magnetron thermostat could cause this.

While in most cases a thermal cutout or thermostat will interrupt all power, making a unit "dead", that's not true here.

In many recent L.G. designs made for Whirlpool, Kitchen Aid, et al, the magnetron thermostat only interrupts power to the high voltage section.

So when this oven has these symptoms, that's the first thing to check.

If it does not cool back down, it is defective and must be replaced.

One should make sure the internal cooling fan is working to cool the magnetron. If not, the magnetron can be destroyed.

A thermostat can only be tripped so many times before it wears out and must be replaced, just like a circuit breaker. Metal fatigue will eventually cause them to fail.

In this model, a failed primary interlock switch could cause the same symptoms, as could a failed cook relay.

An "open" failure of any of these components will keep the high voltage section from turning on.

We have a sound clip of what a microwave should sound like when the cooling fan and high voltage section are operating here.

If while trying to cook, 110VAC is measured across the primary terminals (white and brown wire) of the high voltage transformer, then none of the is the culprit, and the high voltage section is getting power.

That means one of the high voltage components (most likely the magnetron or high voltage diode) is bad.

When high voltage capacitors fail, they rarely do anything but short, which will cause the fuse to blow when you press the Start pad on the keypad.

Fundamentals, people.

Did you ever fix this? And were there any error codes?