On Thursday night Carolyn Jackson didn't arrive to the usual cool comfort of her Red Bank home. She knew right away something was wrong with her air conditioning units.

"The outside was running but the inside wasn't," explains Jackson. "There was no air flow inside the building. So, it was warm upstairs."

She made a change of plans and spent the night downstairs.

"It was very warm. I didn't sleep up there. I slept on my sofa," adds Jackson.

It turned out to be a faulty fan board which had to be replaced by someone with electrical experience.

However, Mike Neidich, owner of Certus Heating and Air, says you can take steps to save on expensive repairs or at least the cost of a diagnostic visit.

It could be as simple as checking your settings.

"They just didn't set the thermostat to the right mode of operation," Neidich says he encounters often. This happens a lot during seasonal transitions. It sounds like a no-brainer, but as we settle into summer make sure your thermostat is set on cool, auto, and at 70° or higher. Programmable thermostats solve this issue.

Then check the air filter.

"Make sure that there's no dirt on it, that the filter can breathe properly. You don't want the filter sucked in," adds Neidich.

Even if it's labeled a "90-day" filter, Neidich says check and replace it every 30 days if necessary, especially if you have pets or a lot of people coming in and out of your home frequently.

With a simple wrench you can remove the top of your outdoor unit and check for debris. Be sure to turn off the power first, usually a lever located on the wall near the unit. Don't let any debris build up inside or around the unit. This often happens after cutting the grass.

"The air flow, that coil inside there, actually drops in temperature," says Neidich.

This causes the unit to freeze up and the air in your home to get warmer.

There's one place, however, where air flow can slow down your A/C system.

"When the unit is running, put your hand up around the duct work to see if you can feel any air flow coming out," suggests Neidich. If there's air leaking, simply cover with duct tape.

Any time your fans don't run, the air isn't cool enough, or the air isn't flowing you can use a volt meter or amp meter, available at most hardware stores, to check the fuses in your A/C units. You can replace yourself in most cases.

The key is to keep the air flowing through the system.

"Our units have to be able to breathe," states Neidich.