Fall is a great time to buy a home for many reasons, and house hunters know to look for their must-have features: Does it have enough bathrooms? Is the backyard big enough for the kids to play? Does the basement have room for a man cave?

But beyond the fun stuff, there are the practical components to think of, and that includes assessing whether the major appliances are going to need repair or replacement soon.

Especially when it comes to the HVAC system, which every home needs to ensure comfortable temperatures year-round, you need to know whether the system is in good shape before you sign on the dotted line.

Here are five signs of HVAC issues in a home:

Leaks and Drips

Take a good look at the floor or ground around all sections of the HVAC system. If you see puddles or moisture, it could mean that water is coming out of a broken condensation drain pan and will eventually lead to costly structural repairs. Have a professional remove the cover ‘off’ the evaporator coil cabinet and carefully inspect the pan.

In the case of a boiler, any leaks or drips are coming from the system could mean faulty water pressure or corroded components.

Unusual Odors

If you smell something ‘strange’, it probably means something is not correct. Musty odors could be standing water, which can lead to mildew-and mold. Gas smell is very dangerous and will need to inspected by a licensed professional. Dirty air smells can be as simple as dirty air filter.

Coil Issues

Indoor coils play a large part in how the home HVAC units function, and the energy used during the year. If you notice that coils seem corroded or at risk of breaking apart, it is a sure sign, they will need repaired in the future. Sometimes that’s a DIY job, but other times, they require professional attention.

Noisy Air Vents

If air vents emit a high-pitched, tuning-fork-like sound, it usually (but not always) indicates a lack of return air. From crushed air duct to a smashed supply air duct register sound is one of the ‘COMFORT’ items that will need to be addressed.

Lack of return air can be caused by something as complicated (and expensive to fix) as undersized or improperly installed ducts, or as simple as a blocked air filter.

Vents also might make a rattling or flapping sound, which is usually due to debris in the duct.

Other Noises

There is a wide variety of the noises you might hear from an HVAC system.

A rattling sound might mean a piece of metal strap has come loose inside the main duct plenum. While squeals or shrieks can indicate a bad belt. A metal-against-metal scraping sound can mean that part of the blower system has worked its way loose.

A chattering sound could mean the compressor, while a clicking outside in the a/c unit could mean the compressor contactor is worn-out and needs replaced by a professional.

A boiler that is making bangs, gurgles or whistles may point to an impending boiler failure.

Any kind of unusual noise from the system is likely a sign of trouble, and these issues are jobs for professionals.

The Take Away

If you suspect the HVAC system needs replacement or repair, you can alert the home inspector to the issue you spotted, and call in an HVAC professional, to help figure out the cause, and discus the fix.

Depending on what they find, you may have an extra bargaining chip to get the seller to drop their price, or, if you are choosing between two homes and all other things are equal, knowing that you have some HVAC repairs or replacement coming up with one might help narrow your decision.

Either way, knowledge is power, and going into the fall home-buying season armed with these tips will help you avoid any surprises after you move in.