You need to use an ammeter - usually the current setting on a multi-meter. The meter should be connected to the circuit in series.
Check the number of amps that your circuit can handle. You should not put devices with more than that many amps (total) on that circuit. Most houses are 15 amps and bathrooms 20 amps.
amprobe
chances are it is a blown fuse. Look under the dash, look for the fuses cover and check the park/lamp fuses. Or check one by one and replace the blown one with another OF THE SAME CAPACITY (AMPS) ... there are 10 Amps, 15 Amps, 20 Amps and 30 Amps ... install only the proper AMPS fuse.
You have to check the label on the unit itself. It will give you all the information as far as maximum and minimum amps.
You can check it out yourself using these formulas. Watts = Amps x Volts. Voltage = Watts/Amps
Borrow a clamp on amp meter and check full load amps. If pulling full load amps then compressor condemned.
as long as the cranking amps are the correct stye it will tell the cranking amps on the battery check your owners manual for the cranking amps for your van or call an auto parts store and ask them what size you need.
usually around 600 amps, but it depends on the engine you have. For example, a larger engine will require more amps than a smaller engine. a typical 5.0 L V8 requires about 650 amps, and some SUVs have larger and smaller engines. So check your engine,and get the right battery.
check battery and alternator
Rockford Fosgate offers a great selection of 900 watt amps. You can also check reviews on the Kenwood 900 watt mono channel amp.
The formula to use is I = W/E. Amps = 20000/240 = 83 amps. Check the nameplate of the equipment that you want to connect to the generator. You can add equipment up to the total of 20000 watts or 83 amps.
A current greater than 5 amps; check for short circuits.