Microwave Not Producing Heat

[SoapCreeker]

Here's a real head scratcher. Our microwave was working one night, the next morning, it wouldn't heat. Lights and clock worked, but wouldnt heat my cup of coffee. Figured the microwave had died and got a new one in town. Plugged it in, same issue. Took old microwave into the house, works perfect. Assuming it was an electrical issue, checked the breaker and all fuses. Everything seems fine. Ran a multimeter on the breaker, shows 120v. Assuming it was the outlet, did the same. It too shows 120v. So the question is, where do I look next for the problem.

Thanks much!

[NH_Bulldog]

Microwaves can have the magnetron simply just fail. How old is it? If two years or less, it may still be under warranty, although some manufacturers consider a magnetron to be a wear and tear item that isn’t covered under warrantee. Either way, they are cheap enough to replaced with a beter quality one

[RollaMo]

Originally Posted by NH_Bulldog

Microwaves can have the magnetron simply just fail. How old is it? If two years or less, it may still be under warranty, although some manufacturers consider a magnetron to be a wear and tear item that isn’t covered under warrantee. Either way, they are cheap enough to replaced with a beter quality one

True, but he purchased a new microwave and it does not work in the trailer either.
Then he mentioned taking the old microwave (that wasn't working in trailer) into the house. And it works just fine there.

Originally Posted by SoapCreeker

Figured the microwave had died and got a new one in town. Plugged it in, same issue.
Took old microwave into the house, works perfect.


Thanks much!

[Gkri]

Originally Posted by SoapCreeker

Here's a real head scratcher. Our microwave was working one night, the next morning, it wouldn't heat. Lights and clock worked, but wouldnt heat my cup of coffee. Figured the microwave had died and got a new one in town. Plugged it in, same issue. Took old microwave into the house, works perfect. Assuming it was an electrical issue, checked the breaker and all fuses. Everything seems fine. Ran a multimeter on the breaker, shows 120v. Assuming it was the outlet, did the same. It too shows 120v. So the question is, where do I look next for the problem.

Thanks much!

Since the microwave works in your house, I would still suspect the outlet. The RV industry standard outlets press the insulated wires into a "V". While you may be measuring 120 V "static", it is quite possible one of the wires is no longer making good contact and not passing the current needed to operate the magnetron. Try another outlet in the trailer and see if the microwave will work. If it does, purchase an "old work" shallow outlet box and a good quality outlet that has pressure plates for the stripped wires. The old work boxes have little flippers that grab the back of the wall (probably luan or similar) to hold them in place. We have replaced almost all the RV type outlets in our Passport.

[flybouy]

I would pull that microwave plug apart and inspect it. Could be a bad connection causing a voltage drop under load.

[NH_Bulldog]

Originally Posted by RollaMo

True, but he purchased a new microwave and it does not work in the trailer either.
Then he mentioned taking the old microwave (that wasn't working in trailer) into the house. And it works just fine there.

Good point! I had a big swing and a miss on that one!

[notanlines]

Originally Posted by Gkri

Since the microwave works in your house, I would still suspect the outlet. The RV industry standard outlets press the insulated wires into a "V". While you may be measuring 120 V "static", it is quite possible one of the wires is no longer making good contact and not passing the current needed to operate the magnetron. Try another outlet in the trailer and see if the microwave will work. If it does, purchase an "old work" shallow outlet box and a good quality outlet that has pressure plates for the stripped wires. The old work boxes have little flippers that grab the back of the wall (probably luan or similar) to hold them in place. We have replaced almost all the RV type outlets in our Passport.

I believe THIS is the solution. I can think of no other scenario that makes sense.

[Raptor Dave]

Originally Posted by Gkri

Since the microwave works in your house, I would still suspect the outlet. The RV industry standard outlets press the insulated wires into a "V". While you may be measuring 120 V "static", it is quite possible one of the wires is no longer making good contact and not passing the current needed to operate the magnetron. Try another outlet in the trailer and see if the microwave will work. If it does, purchase an "old work" shallow outlet box and a good quality outlet that has pressure plates for the stripped wires. The old work boxes have little flippers that grab the back of the wall (probably luan or similar) to hold them in place. We have replaced almost all the RV type outlets in our Passport.

I'll second this ^^^^
Had a similar situation with my water heater. Everything looked good on the meter till I actually turned the heater on and that's when the voltage drops happened not allowing it to work properly.

[workinonit]

Those cheesy receptacles are a fire waiting to happen.

[wiredgeorge]

Originally Posted by workinonit

Those cheesy receptacles are a fire waiting to happen.

The RV and mobile home receptacles are much quicker install at a factory than a residential type as all you do is shove the wires into blades and don't even need to strip or tighten screws. In my somewhat limited understanding of the black art of electrical I have have found that vibration will undo a secure blade-made wire connection over time. Shallow work boxes and residential receptacles are a far more safe and secure solution for RVs.

[jsb5717]

I, too, suspect the outlet. Did the OP try the microwave in another outlet in the RV?

[SoapCreeker]

Thanks for the input everyone. Considered the outlet. But now a new issue has appeared. The refrigerator is not working, the freezer wont even freeze water. So, if we put the outlet out of the equation for the moment, could there be another issue that is related? With us turning the power off and on and flipping breakers, could we have created these two problems?

[Gkri]

Originally Posted by SoapCreeker

Thanks for the input everyone. Considered the outlet. But now a new issue has appeared. The refrigerator is not working, the freezer wont even freeze water. So, if we put the outlet out of the equation for the moment, could there be another issue that is related? With us turning the power off and on and flipping breakers, could we have created these two problems?

I can't see that "flipping" breakers on and off could create these issues. The refrigerator and microwave "should" not be on the same circuit, but is by some chance they are, a poor connection at the microwave outlet would also affect the refrigerator. I believe the refrigerator was a single plug outlet on our Passport and located behind the exterior access panel. Just remove all power and check the outlet(s) for loose wires.

[JRTJH]

Whether the refrigerator issue is related would depend on what type refrigerator you have in your trailer. If it's a gas/electric refrigerator, then it operates on 12VDC and gas if there is no shore power and it operates on 120VAC only if you select the electric element. But that would take several hours to days for you to notice as the refrigerator slowly defrosts and warms up.

So, for most purposes, the refrigerator operates on 12VDC and would automatically switch to gas if there is no shore power at the refrigerator plug.

That said, it's entirely possible that the refrigerator plug AND the microwave plug are on adjoining circuit breakers in the power distribution center and that the connections on the circuit breaker are either corroded or loose. Open your power distribution center (FIRST UNPLUG THE TRAILER SHORE POWER CORD) and tighten every wire nut or screw that you see. Remove each circuit breaker and check that the hot wires are also tight.

This may or may not be your issue, but definitely worth the time and effort before you start paying an RV repairman to do the same thing as his first troubleshooting step.

[LHaven]

Keep in mind that most times a microwave will have its own dedicated outlet and breaker, like the air conditioner, and for the same reason. It's not impossible for the microwave to be sharing its circuit with something else, but it's highly unlikely.

Rather than a meter, my tool of choice for this problem would be a $5 plug in circuit tester [LINK]. It's a fast diagnostic, and once inserted you can even give a good hard wiggle to test whether your outlet may not have been assembled quite solidly. Strange behaviors can occur when a neutral or ground (but not both) is intermittent, and this tool checks and reports on all of them at once.

[SoapCreeker]

Thanks for the advice everyone. I'm going to start with the outlet first. Now the question on that, how do you get the blasted cover off the back? The "directions" on the cover say to push in the square holes. There are four and they are a real pain to push in. Hopefully there is not a special tool.

[LHaven]

If I recall correctly, the box is held together with thick-ish plastic pawls. Keep a little opening tension on the box and just pop the pawls one by one. Again, as I recall, the seam between the front and back halves is not where you would expect it, so choose your tension carefully.

[Kzneft]

I had a similar issue when the RV was running on an inverter. Not sure if you are using an inverter. The inverter was not producing enough voltage for me. Found out the inverter was going bad and only outputting 115-118 volts. The microwave would run, but not produce any heat. New inverter fixed the issue. Other than that the other replies might be in order.

[Larrystegall]

Check the shore power outlet (both legs) for voltage. Undervolt on one or the other will produce your problem. Sounds more like loose neutral as others have stated, but begin at the beginning.