I'm trying to run a 750 watt whirlpool compact microwave with a 2500 watt Cobra inverter. The microwave runs normally, but it won't heat. If I plug it in at my house it heats fine. I'm stumped. I load tested the inverter with two hair dryers and the microwave and it seems to have good output.

Instantaneous surge current can trip the breaker. You need to look at the data plate on the oven to see what the actual draw off the mains is. 700 watts of microwave power is NOT the amount of power drawn when it starts. You have the fan motor and the tray rotator motor to deal with when calculating the correct size of inverter to use with it.

The problem is caused by a bad magnetron, inverter board, "7 years old or less" and possibily the keypad control board.

inverters run on a square voltage unlike normal 110 runs on a round voltage, the only 2 things that won't run on the inverter is fans and electric blankets

hi there, if you're using your power inverter to run your microwave oven isn't it? surely it is not advisable to plug this appliances for this really consume a lot of power...and eventually overload your PWR Invrter..if you use you power inverter in diff. load like lightings or a small dvd plyer and runs smoothly...is your microwave has no deffect if plug in wall socket and still blown the fuse...you have a deffective microwave oven..every time you replace the fuse w/ same type or ampereage and still blown you have a shorted power supply...try to bring your microwave oven in service center...nice day..

magnetron is likely wiped out. never operate a microwave empty.

5000 btu consumes about 500 - 700 W in cooling and obviously it should be running from 2500 W inverter.

It is obviously, but the conditioner has a compressor which needs some more (about 2, 3 times the rated) starting power, which is in it's bigger part reactive power which is not produced by the inverter and depends on the output condensers of the inverter.

It should be tested, and if the start is difficult some more condensers may be added.

It sounds like the fan is failing.
Good Luck,
Gilshultz

There are 8 40A fuses inside this unit. In the following pics you will see a bank of 4 and another bank with 3 of the 4 removed. I'm currently working on mine as it will cost me more to ship and have Cobra repair than I paid for the unit ($133 to repair). Good luck with your problem

I had to buy a 2000 watt inverter type to run mine

your inverter needs to cool at all times , if the fan does not work,try buying a small standing fan to blow cool air to you machine, it is possible that your heater is making the inverter to over heat please avoid using the heater on the inverter