Strong odor when starting Air Conditioner - Contractor Talk - Professional Construction and Remodeling Forum

Since 1977 · 08-11-2009, 10:11 PM

I have a client who was away for vacation. When she returned home and 'fired up the air cond. ' in about 7-10 minutes she noticed a strong smell. Originally it was feared to be natural gas.
I checked the lines inside and out with a detector....nothing.
This has possibly a smell like cat urine [ she just bought the house a year ago] but she has no pets. There are two 'black' spots/rings [urine spots?]on the hardwood floors which she has had professionally re-sanded and clear coated.
This has happened three times, she doesn't want to turn the system on for fear.....
has anyone run into this?
Also. I see plugs in the downstairs trunks that appear to be 1" dia. and I assume they are duct cleaning plugs...not sure.

Any input is appreciated, Thanks!

**ChrWright** · 08-11-2009, 10:15 PM

Could've had critters in the ductwork. Racoon scat smells a lot like that...

Since 1977 · 08-11-2009, 10:18 PM

Quote:

Originally Posted by ChrWright

Could've had critters in the ductwork. Racoon scat smells a lot like that...

Say it aint so.....thats what i told her we may have to take down some main trunks....

it only happens with the cold AIR conditioning... not the furnace/forced air

**ChrWright** · 08-11-2009, 10:27 PM

Chasing smells can be like chasing ghosts.

I had a client with a strange smell a few years ago that went on for months in only one room of the house. It smelled like an electrical fire with a little stinky sock thrown in.

We sniffed and poked and prodded around trying to figure it out--thinking it was a dusty furnace coil, or a shorted outlet, or something buried in a wall.

In the end it turned out to be an old area rug.

flashheatingand · 08-11-2009, 10:43 PM

It wouldn't hurt to spray the evaporator coil with a bleach/h2o solution. Might as well give it a cleaning. Use a condensor coil brush and brush "with the grians" try not to bend the fins on the coil.

neolitic · 08-11-2009, 10:44 PM

Look at the tray at the bottom
of the A coil.
If it isn't draining well, some
nasty crap can start to grow there.
Sitting warm and stagnant while
she's away might be enough.

NickTech · 08-12-2009, 11:44 AM

its probably mold mildew or bacteria building up in the condensate drain. a good areosol coil cleaner or a bleach solution over the coil and through the drain should take cake of the odor. unless its more sinister than that!

Since 1977 · 08-12-2009, 10:42 PM

Thanks to all of you for your responses,going there tomorrow to check the suggested areas.

**ChrWright** · 08-12-2009, 10:47 PM

Quote:

Originally Posted by Since 1977

Thanks to all of you for your responses,going there tomorrow to check the suggested areas.

Here's hoping it's just a little mold on the coil...

DuMass · 08-14-2009, 07:45 AM

Wondering if it might be dirty sock syndrome. I agree that a good place to start would be to clean and disinfect the evaporator coil and condensate drip pan. You may also want to spray the plenum with some Hydro Balance duct and coil disinfectant/deodorizing spray as well.

Since 1977 · 08-16-2009, 04:07 PM

Well I wanted to report that it was.. in fact... buildup from her having the HUMIDIFIER running full time since she got into the home about a year ago!

So we vac'd it out and cleaned/ disifected the coil and told her to keep the 'juice box' off until winter and the static builds up to where her hair is standing on end.

Thank you for all the responses........
Put a fork in this one... its DONE.

neolitic · 08-16-2009, 04:46 PM

"...and they lived happily ever after."
Thanks for coming back to
end the story.

DuMass · 08-17-2009, 08:19 PM

Glad you got the odor under control. It sounds like maybe her humidifier isn't hooked up correctly though. In my area, they are normally connected to run only when the furnace is in heating mode and the blower is running, regardless of the humidistat setting. Also wondering why she would want to be able to add humidity to the air during the cooling season, with the AC running? This seems counter productive.

flashheatingand · 08-17-2009, 08:49 PM

We also hook the humidifier to only operate in Heat Mode. There are exceptions, but, generally, you only want the humidifier to run while the furnace operates as it's the furnace that dries out the air.

The problem is done this year, but if there was a funk caused, I would suspect a problem with the condensate run. It's easy to "do it right" with a condensate pump and run the line to a utility sink, or washer drain.

delta l · 08-18-2009, 06:43 AM

Isn't bleach corrosive to aluminum fins?

flashheatingand · 08-18-2009, 08:30 PM

Quote:

Originally Posted by delta l

Isn't bleach corrosive to aluminum fins?

I wouldn't spray straight bleach on the coil, nor would I advise someone to clean with bleach on a regular basis. But I don't forsee any major damage happening if done once in awhile.

You can pump the system down, and pull out the coil, give it a thorough washing, but in the interest of keeping expenses in check, a little bleach water should be alright.