Looks to be a simple adjustment...
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If you travel at high altitudes or in extreme temperatures, your generator can lose power. In such lower-density air conditions, you can’t operate as many electrical devices as you could under normal operating conditions.
Power decreases 3.5% for each 1,000 feet above an altitude of 500 feet.
For example, to operate at 4,500 feet (4,000 feet above rated generator altitude) multiply 3.5% x 4 (4,000 ft) = 14% power loss. Then multiply .14 x your generator’s power rating: 4,000 watts x .14 = a loss of 560 watts at that altitude.
Power decreases in extreme temperatures by 1% for each 10° F (5.5° C)
above 85° F (29.4°C).
Altitude.....
Power output will decrease 3.5% for each 1,000 ft above Onan’s base rated altitude of 500 feet.
Temperature.....
Power output will decrease 1% for each 10-degree F increase in ambient temp above 85 degrees F.
• The generator is not the only appliance affected by hot weather. Your coach A/C units require more power at higher temps. For example, a temp increase from 85 to 110 requires 20-25% more power to run efficiently. This can also limit your ability to run as many electrical devices.
• Make sure the engine oil viscosity is appropriate for the weather. Onan recommends 15W-40 oil. OnaMax is specially formulated for the operating conditions of your generator.
• If you experience problems, set the altitude adjustment know (if equipped.)
• Make sure nothing blocks the air flow, perform maintenance and set summer/winter preheat levels. Winter=temps below 55, Summer=temps above 55.