According to consumer reports, windows units could be blowing a lot more than just cool air.

To get ready for the hot humid days of summer you may have to haul your heavy, awkward window air conditioner out of storage for the summer season. But, the machine may be harboring mould and other irritants.

Consumer Reports Home Editor Paul Hope says some window units could make you sick.

“Without proper care and maintenance, mould can actually grow on the inside, which has the potential to lead to health problems like wheezing, congestion and throat irritation,” Hope said.

Hopes says one of the first things consumers should do when they get window unit out of storage is to examine it closely and be on the lookout for clusters of tiny black spots along the air duct.

“Cleaning the louvers is a good first step, but if you see mould on them there’s a good chance that there’s more hiding inside the air conditioner. If that’s the case, you really want to consider buying a new one,” Hope said.

To make sure your air conditioning unit works properly, you’ll want to make sure it’s installed correctly.

Make sure your window air conditioner is slightly tilted to the outside so that any condensation or rain water won’t end up on the inside, which could also cause a mould problem. Install the air conditioner’s side panels snugly against the side of the window frame and use the weather stripping foam that comes with most air conditioners to prevent outside air from creeping in. This will save energy and keep pollen and other allergens, outside.

It’s also a good idea to clean the filter of your unit at the start of the season and then once a month after that.

“It will help the machine run efficiently and keep the air it circulates, clean,” Hope said.

The filter can be vacuumed to remove dust and dirt build up and occasionally washed with soap and water.

If you have a portable air conditioner, it should be drained of water to prevent mold.

A light may indicate when the water reservoir needs to be emptied. There may be a drain plug that will allow you to drain the water into a tub or outdoor area. When a portable unit is being stored, the unit should be drained, with the cap off, so it can air out.

Mark Mendell, an affiliate scientist at Lawrence Berkeley National Laboratory who has studied the health effects of ventilation systems, said that living with a mouldy air conditioner “would increase your chances of having a respiratory infection.”