What Direction Should the Air Flow in an AC Unit?

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Which way should the air flow in an AC unit?

You’ve been outside when your air conditioner is running, right? You’ve heard that refrigerator-on-steroids buzzing sound, and felt the hot air rushing out the top of it. Wait. What? It’s not rushing out from the top?

What if the fan is sucking air down from the top, through the unit and out the sides? Turn it off immediately and call an electrician.

The air flow, and fan direction, in an exterior AC unit should be such that it is pulling cool air in through the louvers on the side of the case and ejecting hot air up through the top of the unit. This is because hot air rises, and it's simple physics—we wouldn’t want to engage in a brawl against the way nature has been organized. If your AC unit is attempting to suck air in through the top and eject it down and out through the louvers, you've got problems.

Additionally, the force of the gust of air coming out from the top ought to be strong enough to, say, move a beach ball or flap your gums (decidedly NOT recommended, but a funny word picture nevertheless). In other words, if the column of air being produced by the fan in the AC unit is weak, perhaps it’s not getting enough juice. These units run on 220 AC, like an electric stove. If it has been incorrectly wired to the service panel, the unit will not run correctly, possibly delivering a weak column of air or maybe even running in reverse, which, from your query sounds like a distinct possibility. Again, call an electrician or an HVAC service specialist and have the system looked at. Forcing a unit to run on less voltage than it was designed for will severely damage it.

Depending on the age of the installation, there could be any number of problems. It does pay dividends in the long run to have your system looked over by a qualified technician every once in a while. For newer systems that are younger, it’s perhaps overkill to do this every single year. But for older systems, about fifteen to twenty years old or more, you should be having regular checkups. It’s also a good idea to have your ducts cleaned at least every couple of years, and change the system filter twice a year at a minimum. And again, some of the older units may eject hot air out the front and intake cool air from the back. It just depends--but it's always money well spent to have a technician perform a service call.

Hopefully this tidbit helps explain the situation a bit. There’s no harm in calling in qualified help; if I were you I would have a technician look at it. Until then, if you need to cool down you can always go for a stroll at your friendly neighborhood Wal Mart—it’s like a freezer in there!