Tag Archives: AC Coils

Do You Have A Leaking AC Evaporator (Indoor) Coil?

In many of my blog posts, I go into lots of detail.  For this post, however, I’m trying a shorter format for two reasons: a – our readers are busy, and want useful information in bite-sized pieces; and 2- the causes of leaks in AC evaporator coils seems more varied than the solution.

Symptoms of leak in indoor coils

  • Periodically being told that refrigerant needs to be added
  • AC system and fan runs, but warm air comes from vents

Causes of leaks in evaporator coils

In the HVAC forums I monitor, the posts on leaky indoor coils tend to come in waves, sometime focused in certain geographical areas.  Humid climates tend to increase some of the issues.  Lately the number of posts has been high.  Leaky coil issues are fairly widespread, and are not limited to any particular brand. Listed below are some of the possible causes of leaks:

  • Corrosion of tubes (“formicary corrosion”) increasing due to “tighter” house construction. Corrosion causes pinholes in the copper tubes
  • Corrosive gasses or fumes from defective drywall or other building materials, contents, or household chemicals.
  • AC coils being made of thinner-walled, lighter gauge copper
  • Higher operating pressures in newer equipment
  • Manufacturing defects in tubing

Possible solutions and questions to ask your contractor

  • If your AC and heating system is older (10 years is a benchmark used by some of the municipal rebate programs) or not very efficient, before doing a major repair, such as replacing a compressor, coil, or heat exchanger, you should also compare the cost of replacement.  Most rebates and tax credits require the installation of a new system to qualify.  Plus you’ll lower your monthly utility bills and future repair bills.  If you are in a position to possibly replace your system, you can use our free grid to compare bids.
  • If your AC and heating system is otherwise OK, ask your HVAC contractor if either a plated (tin) or aluminum corrosion-resistant replacement coil will work in your equipment and situation. If you don’t have a reliable service company, you can visit this page to learn how.

If you have experience with a leaky AC coils, either as an owner or technician, please enter your comments so others can learn.



Is Defective Sheetrock Damaging Your A/C and Heating System?

We are following a developing story that could have a major impact on owners of homes or buildings and their HVAC systems.  We’ll post a summary of major points (as they could affect AC and heating equipment) from news sites we have read. We also included links for those who what to read more, and will post more info as new reports come in.  Based on the potential magnitude of this story, and the fact that it surfaced much earlier this year, we find it odd that there have not been more stories in the national media on it.

Essential Points From Complaints and Reports

  1. Some types of drywall (also called sheetrock, wall board, gypsum board, etc.) imported from China and used in the U.S. during the recent real estate building boom are reported to be emitting gas or vapors that corrode metals in air conditioning, wiring, plumbing and more.
  2. Some report that the corrosion is enough to cause the A coils and other indoor components of HVAC systems to stop working.
  3. In addition to corrosion of metals, there are rotten egg smells and health complaints or concerns being associated with gases emitted from the drywall.
  4. There seems to be a connection in humidity and the frequency of complaints. It looks like humid air or moisture increases the reports of corrosion, perhaps by allowing the vapors to collect as an acid.
  5. Reports of the years the drywall was imported and used the U.S. varies. The earliest year we’ve read is 2001, but most reports say the shortage of U.S.  drywall and imports were higher starting in 2006.
  6. Estimates of the extent in the number homes and costs potentially involved vary wildly, but even the lowest estimates we have read are huge.
  7. There is already litigation in progress, and a number of agencies are studying the topic to verify the reports and determine the extent.

Recent Links to Complaints on Defective Chinese Drywall

Manufacturing.Net Oct 15, 2009

National Public Radio  Oct 27, 2009

News Release on PR Web from Chinese Drywall Center Oct. 27, 2009

Wall Street Journal Blog Oct. 27, 2009