Predator 9000 sits unused for 2 years, then bogs down after one day powering owner's A/C

A brand-new Predator 9000 generator that had sat unused for two years ran a homeowner's air conditioner for about one day — then it began bogging down on the condenser and even a window unit. Looking for help, the homeowner turned to Reddit. 

Here's what to know

The original poster laid out the situation in a post on Reddit's r/generator, explaining that a new generator handled the A/C condenser at first, then suddenly stopped. According to the post, it "kind of bogged down, and bypassed the load" even though the machine "has no trouble with everything else in the house."

Much of the discussion centered on the spike required to start air conditioning equipment rather than the power needed to keep it running. For certain equipment, startup can demand far more from a generator than normal operation does.

"Some little generators can't handle that start up current," noted one commenter. 

The difference between startup demand and normal operation is a key part of backup power planning. Just because a generator's published output seems sufficient for normal operations doesn't mean it can power equipment with a large startup demand, such as a large condenser. 

More background

According to the owner, the generator had sat unused since purchase.

"I hadn't used it until I needed it," they wrote. "I bought it 2 years ago."

This delay shaped the advice, with one commenter pointing out that the owner was, in their words, "past your sucky warranty." As a cost-saving alternative, the commenter suggested turning to James Condon's YouTube videos for do-it-yourself troubleshooting instead of formal service. In the commenter's view, DIY fixes were the OP's only option "unless you pay a small fortune to have it analyzed and fixed."

However, not everyone saw the situation the same way. One Reddit user argued that, even if  the generator were undersized for a house A/C, it still "should run a window A/C unit just fine." Therefore, the fact that it also bogged down on a smaller unit suggested something else could be the cause. 

What can be done?

One of the most popular suggestions was for the OP to begin troubleshooting by checking various aspects of their setup. After hearing that the generator would not even handle a window unit, one commenter told the OP to "make sure your eco throttle switch is OFF."

Redditors also suggested lowering the air conditioner's startup demand with a soft-start device. One commenter wrote, "Softstart allows me to use a generac 10kw generator to easily power my home and ac, I have a 3.5t compressor, almost don't notice it." 

Break-in was another point of discussion, with one commenter asking, "Did you break it in? Brushes need worn down to make good contact," while the OP said they suspected "the brushes or the avr are faulty."

The situation also highlighted the importance of regularly testing equipment to ensure it works when you need it, especially in an emergency.  As one commenter put it, "A warning to others, if you buy a generator, use it as soon as you buy it to make sure it works."

Where can I learn more?

These articles dig deeper into the challenges of using a generator to power air conditioning units. 

• A whole-house unit still ran basics but surged the moment an AC load kicked on.

• In North Carolina, a homeowner found soft start was a must for portable-generator AC backup.

• For central air, a soft start can cut portable-generator size demands nearly in half.

• One homeowner kept central AC running through a seven-hour outage using a soft start.

• After five years in storage, one generator started right up after fresh fuel.

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