Microwave Overheating on Generator Power

[duckwonder]

Hi All.  I just had a clearance light repaired at the shop and finally have the van back.  I ran the generator today since it is due to be run (has been about 30 days) and put the heaviest load possible on it for about 15 minutes, including the microwave and a/c.

The microwave (Dometic) was putting off heat all around it (even tho the door was closed) and after 15 minutes was too hot to touch.  Shut down the genset, let everything cool, microwave very hot even after a 2 minutes off / cooling period.  Now I'm concerned about using it, and am wondering what is happening with that.  

Is this an electrical issue?  I am concerned about a FIRE.  Do not want an electrical fire.  Has anyone had this issue, and what is the repair?
Thanks so much.

 

[Stargazer]

The handbook for my PW specifically states not to run the microwave and AC at the same time no matter the power source. Maybe that's why?

 

[duckwonder]

The handbook for my PW specifically states not to run the microwave and AC at the same time no matter the power source.  Maybe that's why?

Hmm, I will have to find that.  When Cummins hooked up the new GenSet, they told me to run both at the same time when maintaining the generator and that's it's ok to run them both whenever.  They may have been mistaken it sounds like.  Maybe I should wait awhile and try the microwave again on gen power (I'm not near shore power at the moment) and leave the a/c off.  I will try that.  Thanks Stargazer.

 

[Stargazer]

In my owner's manual, it's under:

"Motorhome Interior -- Microwave-Dometic:
Your Dometic microwave operates off 110-volt AC power only. To use your microwave you must be plugged into shore power or have the generator running (the microwave cannot be used at the same time as the roof AC unit when operating on the generator)."

Maybe the genset doesn't generate enough?  Don't know why but I never tried.  But to correct above, it doesn't say not to use both when plugged into AC power.

Best wishes!

 

[tx2sturgis]

Did you have something IN the microwave?

 

[Trebor English]

Do you have a Kill A Watt?  Those show voltage and frequency.  You probably can't use the Kill A Watt to measure the amps and watts of the microwave.  Just plug it in to any outlet.  

For generator testing I use low cost loads like 1800 watt hair dryers or 1000 watt space heaters.  If the generator is putting out 165 volts instead of 120 or 45 hertz instead of 60 how much sacrifice do you want to make?

 

[jimindenver]

See what the voltage is while the microwave is running.

 

[rvpopeye]

Need more info.
How many watts is the generator , microwave , AC ?
On the AC BTU if you can't find watts. Plus it will have a surge when starting.

And if you have a meter , yes , voltage while just gen is running and when you add the microwave , and when you add the AC.....

 

[Weight]

Microwave running under voltage. Maybe you didn't kill it.

 

[[email protected]]

To the OP the microwave should never be operated even for a short time without a load. Such as a large glass of water or something else with enough mass to absorb the energy produced. If no load the magnetron or on newer models the inverter will be damaged. Jeff (a retired appliance repairman).

 

[duckwonder]

Need more info.
How many watts is the generator , microwave , AC ?
On the AC BTU if you can't find watts. Plus it will have a surge when starting.

And if you have a meter , yes , voltage while just gen is running and when you add the microwave , and when you add the AC.....

There are many, many things for me to learn how to do.  It is overwhelming.  When I'm ready to learn how to use a volt meter, you're the guy I'm going to PM.  Thanks for trying.

 

[duckwonder]

Did you have something IN the microwave?

Honestly, no.  I am 46 and have never run a microwave empty, this was my first time, had no idea I was not supposed to.  That's why this forum is a great thing.  Sometimes the obvious answer is the best one.  Thanks for not making me feel awful about it.  Best to you, and thank you.

 

[duckwonder]

Do you have a Kill A Watt?  Those show voltage and frequency.  You probably can't use the Kill A Watt to measure the amps and watts of the microwave.  Just plug it in to any outlet.  

For generator testing I use low cost loads like 1800 watt hair dryers or 1000 watt space heaters.  If the generator is putting out 165 volts instead of 120 or 45 hertz instead of 60 how much sacrifice do you want to make?

I will look into  Kill A Watt because I like the double duty for voltage and frequency and it seems I need something like this if I'm going to be in the van as much as I think I will.  It will take time for me to learn these principles and learn how to operate these types of tools.  Certainly appreciate the suggestion.  Thank you!

 

[duckwonder]

Thanks to everyone.  Here's what I learned!
1.  Never run a microwave empty.  I'm lucky I did not start a fire.  And that the microwave still works.
2.  Running my a/c and lights, tv/dvd is enough of a load to exercise my Onan 2800 Generator.  Don't need to run the microwave.
3.  I do have the ability on generator power to run both the a/c and the microwave at the same time - to say, heat up a cup of coffee or quickly warm up some soup.  3 minute limit will be my new rule.
4.  This forum is very helpful.  Thank you to you more experienced and helpful folks.  I shall try to learn from your examples.
5.  I am going to learn something about a volt meter and how to use it.

Best to everyone!

 

[tx2sturgis]

I am 46 and have never run a microwave empty, this was my first time, had no idea I was not supposed to. 

This probably accounts for the above normal heating...running it for 15 minutes without a 'load' is not good for a microwave. But if it still works, then maybe it survived. It does tend to shorten the life of the magnetron, which is the expensive part that does the 'heavy lifting'....

Anyway, I'm glad you told us, this is how we all learn stuff...

Take care!