As spring approaches quickly and summer isn’t too far off, tens of thousands of Dallas residents are contemplating A/C replacement.  The prospect of getting rid of that old, inefficient HVAC system and replacing it with a technologically advanced, high-efficiency new system is an idea that gets homeowners both excited and anxious.  And in fact this time of year is a great time to be proactive in replacing furnaces, coils, condensers and heat pump.  Truly “tis the season” to invest in your home’s comfort and to also start saving serious money.  In this month’s blog we wanted to dedicate a few minutes to what we at Classic Heating and Air think is the MOST important part of the air conditioning installation (sometimes repair) process, pulling proper vacuum.

Pulling vacuum is the process of evacuating a refrigeration or air conditioning system (including refrigerant lines, coils, etc) of all unwanted contaminants and particulate primarily dirt, water and air.  This is done by lowering pressure within the system to reduce the boiling point of water, at which point (generally 27.75 inches Hg) vaporization occurs.  The process of pulling vacuum is performed to rid the system of these potentially harmful substances to ensure that the refrigerant in the system has a clean, pure environment in which it can operate best.  Not pulling proper vacuum can lead to:

  1. Premature corrosion
  2. Line restrictions
  3. Mechanical breakdown (compressor, expansion valves)
  4. Lower efficiency
  5. Ultimate system failure

From industry manufacturers and popular HVAC resources there are several guidelines and requirements of pulling a good, proper vacuum.  This list includes:

  1. Using a high-accuracy digital micron gauge
  2. Removing valve cores
  3. Larger, high-rated hoses and manifolds
  4. Changing the vacuum pump oil after every installation
  5. Pulling system down to at least 300 microns
  6. Allowing system to stand for 20-30 minutes following pull-down


At Classic Heating and Air we are proud to follow these steps and others during EVERY air conditioner installation.  We believe that a job done right the first time is both expected and appreciated by our customers and actually is more profitable to our company by avoiding callbacks, repairs, and warranties. The common problem throughout our industry however is that many companies and/or technicians are either not properly trained or do not dedicate the proper amount of time to correctly pull vacuum and properly repair or install air conditioners.

So as one can see an installation is not just an installation. Pulling proper vacuum is essential for your air conditioning investment to operate properly, efficiently and ensure a long trouble-free service life. This spring and summer whomever you choose to install your air conditioning system make sure they are doing it right…ask questions, get involved. If that company cannot answer your questions or show you exactly what,when, or how they are installing your new air conditioner then give Classic a call!  When we say our service “goes Two”, that means our installation process does as well!