When making a major investment like purchasing an air conditioning system, you need to do your homework. Warranties, Optimization, and Service after the install are factors that should be considered. Here is a handy check list.
Check your local Better Business Bureau.

Look for the companies rating and frequency of complaints.

Call the city in which the work will be performed.

Ask if they are licensed with that municipality.

Ask for a copy of their liability and workman’s comp insurance.

This protects you if the workers get hurt on your property for injury. Liability protects your property if they cause property damage like floods, or fire.

Check to see if they are approved with the manufacturer as “Specialists”.

Trane has Trane Comfort Specialist and Rheem has Top Contractors. This equals to extra training and a working knowledge of the equipment they will be installing.

Ask friends and family for a referral.

Friends and family are a great resource for contractor referrals.

Get a detailed proposal.

This is a big one and a sign of a good contractor. Does it have a lot of fine legal print? This usually puts the rights of the contractor first. Look for signs of charge to the customer for warranty service after hours or weekends.

Equipment Warranties.

Make sure you have a written warranty for equipment and labor.

Ask if they use subcontractors.

We have found that subcontractors do not do as good a job as regular full time staff. The full time technicians usually attend company meetings and regular training sessions. They tend to follow company policy and procedures better.

Get more than one estimate.

Make sure you’re comfortable with the rep from the company. Did they do a thorough examination of the entire scope of the home? Did they cover and address all your concerns? Compare estimates for the best value.

Are they pulling/and willing to pull a permit?

If a contractor is telling you that you don’t need a permit beware of what else he or she may be hiding? You are required by law to have a permit for every installation. It also helps protect you.