Contractors are a dime a dozen, but how do you know if yours is any good? If you didn’t do your homework, chances are you could wind up with an air conditioning contractor that just isn’t up to snuff.

Below, we list six signs that you picked the wrong air conditioning contractor. Do any of these apply to you?

1. Your contractor doesn’t take the time to accurately determine your air conditioner’s size.

Seems pretty basic, right? If your contractor doesn’t do this, he is definitely screwing up.

2. Your contractor doesn’t give you a written agreement.

You are entitled to know what’s going on with your air conditioning system. A good contractor will provide a written agreement detailing the desired outcomes of the job.

3. Your contractor doesn’t give you a service warranty.

This is a huge red flag. If your contractor doesn’t stand behind his work, your air conditioning system could very well start malfunctioning as soon as he gets his paycheck.

4. Your contractor isn’t NATE-certified.

The North American Technician Excellence (NATE) is an independent, non-profit national organization that ensures quality within the HVAC industry. If the technician servicing your air conditioning isn’t certified, he might not be using the most modern and safest techniques.

5. Your contractor doesn’t check out online.

You’re probably already great at Facebook stalking. Use those same skills to make sure your contractor isn’t going to make your air conditioning worse instead of better. Check their standing with the Better Business Bureau, as well as reading online reviews.

6. You called the cheapest contractor you could find.

You might get away with buying off-brand peanut butter at the supermarket, but don’t go calling the cheapest contractor you can find just because you’re trying to save a buck. Skimping on your air conditioning system may save you in the short term, but you’ll be wasting energy (read: money) in the long term – and, ultimately, you’ll probably need additional repairs sooner than if you had hired a good contractor in the first place.