WML75011HV OTR Low-Profile Microwave

Welcome to another edition of Neli’s DIY Appliance Repair Series. Today we’re taking a look at Whirlpool’s new low-profile microwave series. They’re over-the-range (OTR) microwaves and have some nice changes.

The door opens with a button and solenoid instead of a push-button linkage setup. That’s good because sometimes the linkage would break on manual designs, and you couldn’t shut the door because it would jam. The new style lets you open the door manually with no problems.

Its 1,000-watt, 1.1 cu. ft. capacity in a low-profile design is smart. Sensor cooking prevents overcooking, too. It has all the standard options found on other microwaves, making this a good fit in a small space.

This next feature isn’t a big deal, but for some customers it’s a deal breaker. Making popcorn has always been an issue because too many kernels didn’t pop. They finally updated the technology and now you can set the number on the display and rarely will it leave even one kernel unpopped. Good to know, right?

Only a Few Repairs

These units have been around for a few years and nothing stands out as a repetitive problem, such as the door switches constantly failing. Whirlpool updated the design of the interlock by adding a fourth microswitch which rerouted the current load, making the switches more reliable.

I had a turntable motor call just once. It wasn’t the motor, but the gear cracked in two pieces. Simple fix and all was good. Like I said, only a few repairs. But that doesn’t mean they won’t fail at some point. Here are the WML75011HV error codes you may see:

WML75011HV Error CodesAs is common with most appliances, anytime you have an error, try to power cycle the unit and try again. If the error code repeats, it’s probably a legitimate error that needs more troubleshooting.

F2E1 – Touch pad failure

Try running your fingers over the buttons once or twice while pressing hard. Sometimes the earth rubber or mylar gets wrinkled or bunched up and loses contact temporarily. It may work, but if not, try reseating the connections. If that fails, you don’t have any other choice but to replace the touch panel.

F1E4 – MW Relay

This is the relay that supplies 110 vac to the high voltage side. If the contacts get stuck closed, you check the resistance of the contacts. If they’re shorted, it’s likely a bad main control (ACU).

Some Causes of No Heat in a Microwave

One of the most common problems with microwaves is no heat. There are plenty of causes for this, and I’ll explain a few of them here.

Before troubleshooting a microwave, you need to understand how it generates the “heat”. The concept isn’t difficult to understand. The main control sends line voltage to the input of the primary coil of the high-voltage transformer from the MW relay contacts on the ACU board.

The line voltage (110vac) is stepped-up to 2,000 volts. A voltage-doubler circuit made up of the high-voltage diode and high-voltage capacitor sends 4,000 volts to the input of the magnetron. The voltage energizes the magnetron and begins to output microwaves used for heating.

If any single element in the circuits were to fail, the microwave no longer heats. In my experience, it’s always best to replace the mag, cap, and diode, even if they check good with a meter. If you understand electronics and the potential problems with loads creating opens in a circuit, then you understand why it’s best to replace all three components.

If you decide to repair your microwave because of a no-heat condition, please don’t take any chances without first contacting Neli to set up an appointment so we can walk you through the safety procedures. Microwaves work with dangerous high-voltages present unless you know how to discharge them and make it safe to repair.

Failed Door Switches

A second cause of no heat in a microwave stems from bad door switches. Some units have three, and some have four microswitches used to confirm a closed door before allowing operation.

The monitor switch detects the position of the door. If this switch fails, a likely result is a blown line fuse in the input power circuit. The other switches work together to turn the interior light on, and tell the ACU the door closed properly, and it’s now OK to allow normal operation.

I always replace all the switches to make sure the issue won’t repeat. It makes sense to me because I can also make other repairs as necessary. Here’s a tip: The switch holders normally don’t make removing and replacing the switches easy. Plastic hooks break easily, so consider replacing the holder and the switches as one part. Most of the manufacturers sell them as a complete unit.

If you enjoyed reading my post today, please let me know in the comments below. Neli loves comments and opinions! If you would like to experience the new way to repair your appliances, set up your appointment here.

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