When your air conditioning stops working you don't want to be without it for long, but it can be difficult and stressful to know who to call or what to look for in an AC repair company.

We rounded up the best tips and quotes from HVAC/heating and air experts to help you find a reliable, quality local professional who can expertly diagnose, repair, or replace your AC unit.

Tips for Identifying a Reliable, Professional AC Repair Company

1. Respectful Providers Offer Reliable, Quality Service

"Find out if they were affordable, timely, neat, and professional. Make sure that their technicians were cordial, neat, respectful and did quality work." - Finding an Air Conditioning Repair Company You Can Trust, Doc Savage Heating and Air Conditioning Inc.; Twitter: @DocAirSavage

2. Safety Should Be Their Top Priority

"You have to consider carbon monoxide, leaky gas and other issues that might potentially put your family at risk. Professionals … are properly trained to look after such threats and deal with it when it happens." - Five Good Reasons To Hire A Professional HVAC Company, Eagle Air; Twitter: @EagleAirHCS

3. Steer Clear of Repairmen Without a License

"Hiring an unlicensed, inexperienced company or doing-it-yourself will impact the quality of your repair and has the potential of creating a dangerous situation for everyone in your home." - The Importance of Hiring a Licensed HVAC Technician, Heritage Mountain Heating and Cooling; Twitter: @HeritageMT

4. Ask About Energy Star Products

"ENERGY STAR qualified products meet strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and offer significant long-term energy savings. Contractors should be able to show you calculations of savings for ENERGY STAR heating and cooling equipment." - 10 Tips for Hiring a Heating and Cooling Contractor, Energy Star; Twitter: @ENERGYSTAR

5. Search for a quality repair company before you need repairs.

"This means that when repairs are necessary you will already know who to call." - Hire the Best to Keep Your AC Running, ASAP Air; Twitter: @asapair1

6. Ensure that they are bonded.

"A contract license surety bond is needed as a precaution against unfair dealings as well as a kind of financial insurance in case something with the agreement goes wrong." - Svetlana Guineva, 6 Tips on Choosing a HVAC Contractor, Buildings.com; Twitter: @BuildingsMedia

7. Try an online search of review websites.

"These sites are handy because they provide information about the personal experiences of people who have hired the particular technician before, so you know that the information is accurate." - Erin Doman, 12 Tips for Hiring the Best Air Conditioning Technician, Compact Appliance; Twitter, @CA_appliance

8. Don't forget about traditional sources.

"Newspapers, phone books and discount mailers can be excellent resources for homeowners looking to hire local service technicians." - How to Hire an HVAC Contractor, Yellow Pages; Twitter: @YP

9. Get an estimate in writing before signing a contract.

"This will give you a good idea of how much you are expected to pay. Avoid getting estimates over the phone as the contractor can easily renege on their agreement." - How To Find The Best AC Repair In Your City, Smith & Willis; Facebook: @smithandwillis

10. Seek out a company known for its honesty and reliability.

"A reliable heating and air conditioning system is essential for your home comfort and efficiency. Your AC system needs proper care and attention to help protect its value and keep it in top working shape." - Adam Bunyard, President Snappy Electrical, Plumbing, Heating, & Air; Twitter, @snappysvcs

11. Get multiple estimates.

"Try to find at least three possible technicians for your consideration so that you'll have multiple options. From there, you can decide based on credentials, availability, or costs." - Erin Doman, 12 Tips for Hiring the Best Air Conditioning Technician, Compact Appliance; Twitter, @CA_appliance

12. Ask if the company runs background checks on its employees.

"HVAC technicians will be working in and around your home and close to you and your family, and you want to know that they are trustworthy." - Questions to Ask HVAC Technicians Before Hiring, Comfort Experts Inc.; Twitter: @ComfortExperts

13. Ask friends and family for a referral.

"Odds are that you know someone who has the same air conditioning unit as you do. If they have a company they trust with all of their maintenance needs, then there's a good chance you'll be able to use that company's services comfortably, as well." - 5 Tips to Help You Hire the Best Licensed AC Technician Around, Pioneer Heating and Air Conditioning Inc.; Twitter: @pioneercomfort

Comparing AC Repair Companies

14. Promptness cannot be underestimated.

"Prompt service is utterly necessary especially when it comes to making urgent repairs in your system. You wouldn't want your employees or family members to freeze to death while waiting for the repairmen, would you?" - Cedric P Loiselle, Qualities You Should Look for In An HVAC Company, EzineArticles; Twitter: @EzineArticles

15. Don't always go with the biggest company.

"Larger HVAC companies tend to prioritize commercial clients over residential, sending the most experienced technicians to commercial jobs. That could mean your residential technician has other priorities and is likely new or inexperienced. Don't hesitate to settle on a family owned company, you'll often receive lower prices, better service, and more experienced technicians." - Cory Contreras, Owner, Lex Air Conditioning and Heating;How to Hire the Best HVAC Contractor or Repairman, Expert Beacon; Twitter: @ExpertBeacon

16. Check for reviews on the company website.

"Most companies have their profiles online. The ratings and reviews that they have received is a good indication of their service quality." - Air Conditioning Repair: Hire the Right Technician, Countryside Plumbing and Heating Inc; Facebook: @Countrysideph

17. Don't rush things when looking for a repair company.

"Even if you have an emergency, for example, your air conditioning has gone out and it's 94 degrees outside, the time that you spend gathering details beforehand can save you money and a lot of headaches." - Mike Waggoner, How to Hire the Best HVAC Repair Technician, Waggoner's HVAC; Twitter: @WaggonersHVAC

18. Find out if they offer 24/7 emergency service.

"A quality provider will have an emergency number that's staffed 24 hours a day, seven days a week and enough technicians to respond when the weather is awful and the calls pile up." - Danny Lipford, Tips For Dealing With HVAC Pros, Today's Homeowner; Twitter: @DannyLipford

19. Ask for references from customers.

"A professional heating and air conditioning company should have a list of recent customers that you can refer to in order to verify that the company in question performed the work in a timely manner and to the customer's satisfaction." - How to Hire an Air Conditioning Repair Professional, Hixon Heating and Air Conditioning; Twitter: @hixonheatairga

20. Don't be afraid to go green.

"You'll never know just how green a company is unless you take the time to ask them about their eco-friendly policies." - 5 Tips to Help You Hire the Best Licensed AC Technician Around, Pioneer Heating and Air Conditioning Inc.; Twitter: @pioneercomfort

21. Check out consumer review websites.

"Many disgruntled and satisfied customers share their personal experiences about specific contractors. The feedback section of the rating sites offer good insights in regards to the quality of service that the contractors provide." - How To Hire An AC Repair And Maintenance Company, OK Heating and Air @OKHeatingAndAir

22. Be wary of the lowest bidder.

"They might say they will come out to inspect your HVAC for $29.99 or even for free, but they have to make up the cost elsewhere. That's when you get slammed with high repair costs, which most people end up paying because the technician is already at their house." - How to Choose an Air Conditioner Repair Company, Donley Service Center; Twitter: @donleyservice

23. Check their BBB rating.

"The Better Business Bureau (BBB) is a very helpful if you want to double check the consumer ratings of an HVAC contractor. The website shows whether there have been any customer complaints against the specified company." - Svetlana Guineva, 6 Tips on Choosing a HVAC Contractor, Buildings.com; Twitter: @BuildingsMedia

24. Does the company offer the latest technology?

"You can spot a good contractor from a bad one if he offers that you use good, up-to-date machines that you can incorporate in your home." - Karl H. Abbott, Choosing a Heating and Air Company and What Qualities to Look For, EzineArticles; Twitter: @EzineArticles

Evaluating the Credentials and Qualifications of AC Repair Companies

25. Ask about the company's certifications.

"Most leading residential contractors belong to the Air Conditioning Contractors of America(ACCA) or the Sheet Metal and Air Conditioning Contractors' National Association (SMACNA). Both sites provide listings of heating, cooling, ventilation and refrigeration contractors in your area. Look for contractors whose technicians are certified by North American Technician Excellence (NATE) and/or partnered with ENERGY STAR." - How to Choose a Contractor, American Council for an Energy-Efficient Economy; Twitter: @ACEEEdc

26. Make sure they perform an evaluation of your home's system.

"A good contractor will inspect your duct system (if applicable) for air leaks and insulation and measure airflow to make sure it meets manufacturer's specifications." - 10 Tips for Hiring a Heating and Cooling Contractor, Energy Star; Twitter: @ENERGYSTAR

27. Evaluate their online presence.

"Do they have an easy to navigate website that provides you with knowledge, education and easy to answer questions? Are they active with Social Media - connecting with their customers, getting their feedback and tailoring their services to the evolving needs of their customers? If the answer is yes to these questions - you can feel confident about their dedication to growing and improving their business." - Chris Hays, How To Hire The Best Heating And Cooling Company; Twitter: @Hayscooling

28. Ask if they have worker's compensation insurance.

"You may also want to find out if the contractor has worker's compensation insurance in the event they are injured on your property." - How to Choose a HVAC Contractor, WikiHow; Twitter: @wikiHow

29. Ask to visit them at their repair shop or office.

"They should have an office or shop facility, and they should not be ashamed to have you visit them. An office or shop is an indication that the company has been in business and intends to remain in business." - How to Choose a Contractor, American Council for an Energy-Efficient Economy; Twitter: @ACEEEdc

30. Avoid anyone who works "on the side" or "under the table."

"Usually, these types of contractors work at nights and on the weekends. "On the side" contractors often don't have liability or worker's compensation insurance, and are not fully licensed." - Which AC Company Should You Hire?, AlertAC; Twitter: @servicealertac

31. Get staffing, warranty, and maintenance agreements up front.

"Make sure the contractor has adequate staff to install the system and respond promptly to service calls. What guarantees, warranties and follow-up service are offered? Warranties vary, so it's important to know what is included in the warranty and what is not." - Questions to Ask when Replacing Your HVAC, Touchstone Energy Cooperatives; Twitter: @TSECooperatives

32. Find out if they've received any awards or accolades.

"A company that is at the top of the industry will have awards and accolades denoting their success." - How to Choose an Air Conditioner Repair Company, Donley Service Center; Twitter: @donleyservice

33. Be wary of deals that seem too good to be true.

"Beware of price estimates that are too low - granted, you want to save money and avoid costly HVAC repairs whenever you can. However, cheap prices are usually an indication of a contractor or technician that is cutting corners and not doing things according to the manufacturer's specs." - 4 Things to be Aware of Before Hiring an HVAC Repair Technician, HVAC Tips

34. Don't settle for a company that does not have NATE-certified technicians.

"Consumers can rest assured that with a NATE-certified technician, they are getting the best installation and service for maximum comfort and economy in their heating and cooling system. Better installation and service mean longer life for your heating and cooling equipment and increased energy efficiency." - Why Should I Choose a Contractor with NATE-Certified Technicians?, North American Technician Excellence (NATE); Twitter: @NATEtechnicians

Tips for Dealing With AC Repair Companies

35. Understand what a professional technician should do when inspecting your AC system.

"The technician should check for correct amount of refrigerant, test for refrigerant leaks using a leak detector, capture any refrigerant that must be evacuated from the system instead of illegally releasing it to the atmosphere, check for and seal duct leakage in central systems, measure airflow through the evaporator coil, verify the correct electric control sequence and make sure that the heating system and cooling system cannot operate simultaneously, inspect electric terminals, clean and tighten connections, and apply a non-conductive coating if necessary, oil motors and check belts for tightness and wear, and check the accuracy of the thermostat." - Maintaining Your Air Conditioner, U.S. Department of Energy; Twitter: @ENERGY

36. Ensure you have all permits in place before work begins.

"Most companies will file permits on your behalf at the local building codes office. But don't assume that it has happened. Check with the permitting office first. Work done without proper permits could result in a fine and time delay." - How to Choose an HVAC Company, Fredericksburg.com; Twitter: @NewsInTheBurg

37. Make sure you have a contract before work begins.

"Important details to ask for in writing are the dates on which the work will be performed, the cost of all fees, labor, and equipment, potential future fees such as upgrades, and payment due dates." - How to Choose a HVAC Contractor, WikiHow; Twitter: @wikiHow

38. Spell out payment terms clearly.

"Stagger payments and tie them to specific stages of the project, so you can hold back if the work is progressing slowly, and outline this payment schedule in the contract." - Rachel Wray Thompson, How to Work With a Contractor and Not Get Ripped Off, Apartment Therapy; Twitter: @AptTherapy

39. Double check the contract before you sign.

"A complete contract should state clearly all tasks to be performed, all associated costs and the payment schedule. Never sign a blank contract or one with blank spaces. Guarantees made verbally by the contractor should be written into the contract. It should state how long the guarantee is valid, what it covers and who is responsible. Make sure to keep a copy of the contract and any receipts in a safe place with your homeowner's manual." - Choosing a Contractor: HVAC Heating - Ventilation Air Conditioning, BBB and the Idaho Division of Building Safety; Twitter: @bbb_us and @IDAHOgov

40. Don't underestimate the value of niceness.

"This is more important than most people realize - Are they nice folks who are easy to communicate with? You'll need somebody you feel comfortable working with. After all, you're trusting your house to them." - Aaliyah Arthur, How to Find a Good HVAC Contractor, EzineArticles; Twitter: @EzineArticles

41. Don't go with the most expensive equipment.

"Just like how a Ford and Lincoln make the same car, but have different aesthetics and pricing, a quality HVAC unit can be purchased for the lower price than a premium brand." - Cory Contreras, Owner, Lex Air Conditioning and Heating; How to Hire the Best HVAC Contractor or Repairman, Expert Beacon; Twitter: @ExpertBeacon

42. Look to build an ongoing relationship.

"You don't want to call a new company every time you have issues with your unit. There won't be any continuity of service or historic knowledge. Look for someone who wants to earn your business over and over." - What to Look for When Hiring an AC Repair Company, EasyAC; Twitter: @EasyACFlorida

43. Choose a company that stands behind their work.

"Air conditioning work is done by hand, and as such, is occasionally susceptible to human error. If the company isn't willing to stand behind their work, you don't want them working for you." - How to Choose an Air Conditioner Repair Company, Donley Service Center; Twitter: @donleyservice

44. Double check your warranty yourself.

"Find out from the manufacturer whether your equipment is still within the warranty period. Call the manufacturer's customer support number with the model number, serial number, and (ideally) date of installation. Once you know whether your unit is under warranty, tell your contractor. Otherwise, you may pay full retail cost for a part that the contractor bought at the wholesale price -- even though you should have gotten it for free." - Chris Brooks, How to Get the Most from your HVAC Warranty, Furnace Compare; Twitter: @FurnaceCompare

45. Look for cost savings with special offers or coupons.

"Keep your costs down by checking around for available rebates on energy-efficient ENERGY STAR qualified heating and cooling equipment." - 10 Tips for Hiring a Heating and Cooling Contractor, Energy Star; Twitter: @ENERGYSTAR

46. Get every little detail in writing.

"Don't put yourself and your wallet at risk of hidden costs, surprisingly expensive repair parts and exorbitant labor fees. Talk with the technician and get everything in writing before the repair begins, and you won't have unhappy surprises." - Mike Waggoner, How to Hire the Best HVAC Repair Technician, Waggoner's HVAC; Twitter: @WaggonersHVAC

47. Understand what a maintenance check-up should include.

"A typical maintenance check-up should include a technician checking thermostat settings, tightening all electrical connections, lubricating all moving parts, checking and inspecting the condensate drain, and checking controls of the system." - Maintenance Checklist, ENERGY STAR; Twitter: @ENERGYSTAR

48. Ask for copies of their insurance documents.

"If they don't, then you could be held responsible for any accidents on your property. There should be a one-page certificate of insurance that you can verify." - Erin Doman, 12 Tips for Hiring the Best Air Conditioning Technician, Compact Appliance; Twitter, @CA_appliance

49. Time your tune-ups and maintenance for off-peak times.

"Arrange for service calls before the start of heating or cooling season. You'll get better attention and have more flexibility when scheduling the appointment." - Danny Lipford, Calling in an HVAC Pro, This Old House; Twitter: @ThisOldHouse

50. Trust your gut.

"If you get a bad feeling about any part of the process, get a new contractor." - Jason Fitzpatrick, How to Hire a Contractor without Getting Hosed, LifeHacker; Twitter: @lifehacker