I have a two year old central A/C unit. Every 2/3 months the unit shuts off.

I called the rep/maintenance company and they have given me the following response:

  • The cause of the issue is algae building up within the drainage line
  • This is due to the climate in Florida
  • This is extremely common, and in fact comprises the majority of their service calls

Their solution is to:

  • Shop vac the drainage line
  • Pour bleach down the line

I have asked co-workers, family members in state, and a friend who's father has been in A/C for a few decades in the south an no one else has heard of this / has this issue.

This was most definitely not explained during the purchase of the new unit.

Does anyone know if this normal? Am I getting hosed?

  • I think the technical part of the question is within scope. Sep 11, 2010 at 11:03

3 Answers 3


I live in South Florida and I too have to do this. My house has 2 AC systems. One of them clogs up after about 3-4 months, the other never has. I'm not sure what the difference is, but ever since I started putting a bit of bleach in the condensate line every time I change my filters; I've had no clogs since then.

Assuming this is actually your problem, I would suggest that you do the same.

  • Seeings though you are in FL and have the same issue, and treat it with the proposed solution I think this is probably the best answer I am going to get. Thanks.
    – blu
    Sep 13, 2010 at 19:03
  • 1
    +1, I put a little bleach in the condensate trap every year. The frequency varies by location, and if it's too frequent, you may be missing the source. The shop vac is the easiest way to clear a line once it becomes clogged.
    – BMitch
    Jul 5, 2012 at 13:17
  • I just moved from FL (central near Melbourne) and we had this issue too. A little bleach down the drain twice a year and we were good. The first time it was so bad we used an air compresser to blow it out. It was the drain line that runs outside that would clog.
    – zk.
    Jul 5, 2012 at 17:20

use of bleach over time will corrode your pvc line ; - use distilled vinegar; probably white - it will not damage your line ; I work homeowner claims and see a dozen of these type claims every couple weeks; probably couple hundred a year from FL.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Feb 12, 2020 at 16:28

I don't know about the shop vac, but I've heard the bleach suggestion numerous times and it sounds reasonable.


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