Not sure how you can have your AC serviced with having the evaporator in the garaged “touched”. They should have checked for dirty filters and condensate pan/pump operation. You could be smelling mold from the condensate pan? Is the unit in the garage a furnace, or just an air handler for the AC? If it’s a furnace, does it have a humidifier on it that could be leaking or moldy?

Thank you. I believe it is an air handler only in the garage, and you touched on an important point. There was in 2006 a humidifier attached to the unit in the garage. i used it for a little while, a year, and then shut off the water to the humidifier and turned it off. i dont use it. but it could be that. would you know how i remedy the problem if it is the humidifier being leaky or moldy?

The humidifier will have either some sort of pad that gets wet or drum that has a cover/pad that gets wet and a pan the drum rolls in. Either of these can get moldy and can be removed and cleaned. If they haven’t been used in a long time and the water is shut off, and didn’t smell until recently, that’s probably not the source.

Servicing the outdoor unit and not doing anything to the indoor unit is not likely to cause an odor indoors. Is it possible you have a wildlife or mouse problem in the wall or garage? Was the blower unit checked for a source of the smell? Was the condensate pan and pump for the indoor unit checked and cleaned if necessary? If there is nothing in the blower/air handler housing or vents, then the AC is not the source of the smell.

That makes sense. Out of all those things, the only realistic possibility would be the condensate pan and pump for indoor unit checked. how do i do this? theres no rodent problem, blower unit by condensor smells fine, air handler smells fine, and in general the A/C guy and i examined the air handler together and everything looked fine, was working well and was clean down below where the air comes up. It really smells just like the sawdust in the attic, but theres no real connection between the attic and my downstairs A/C unit. Very hard problem to diagnose, however you are helping a ton ! all the issues with sawdust smell happened the day after the A/C guy cleaned the outside coils. hence the connection to the a/c unit.

Saypoint, you have had experience in the business though and it helps. Going through your questions, yes, there is a pump that takes the water outside through a pipe. i dont see an issue there. you have the config correct. outside condensing unit, garaged air handler, with ducts work going to room. the a/c guy cleaned the coils with mostly a hose, no cleaning agent. the upstairs unit has its own condensing unit right to the side of the main one, and an air handling unit in the attic where the smell is. I did turn on the upstairs unit for a few days in June because the a/c guy said it would help take the load off the downstairs unit. but after a few weeks i shut it off because my a/c bill here in Arizona was $355 per month.

I think i am going to air out the house, turn on ceiling fans etc. run candles. just for the short term until i can figure it out. i havent run the upstairs unit much at all but it could possibly still be the source of the problem.

“An air handling unit in the attic where the smell is”. The smell is in the attic?

you could have a clogged condensate drain or moldy condensate pan in the attic unit. You may just have to wait for the smell to go away, or have the upstairs unit serviced.

oh i am sorry i wasnt clear. the downstairs smells like the sawdust in the attic. that is the problem. but there is no connection between the attic and my downstairs. I had the upstairs air handler serviced and everything went ok. Possibly the smell could be radiating from the attic to the downstairs somehow with all the heat. Be glad you dont live in AZ ! Thank you.

Did you ever find out what caused this? We are experiencing the same issue. Did it go away?

Jay Bee, it sort of did go away. i say sort of because once in a while i smell something. I did replace my A/C unit after this original post. But i have it narrowed down to 2 possibilities. My attic in my upstairs does smell like the sawdust so maybe there is some channel getting a whif of the sawdust smell and circulating it into the hvac system downstairs. But i think the 2nd thought is more probable. Downstairs my cabinets are a bit older. 25 years (the age of my house). thats where i smell it sometimes. i am going to either replace the cabinets or have them maintenanced. they smell like dry wood if that makes sense. i did have a full house cleaning and they cleaned out all the cabinets. that helped too. not a normal cleaning but a deep cleaning of every area of my house. Hope this helps.

I have a similar problem w/ house smelling like sawdust. It’s a 2 year old house. I smell it when entering the house through the garage through the laundry room and in our home office. I thought it was maybe drywall dust from drywall work we had done but that was vacuumed up and I had the ducts cleaned. We just had hvac work done to reseal an area in the attic b/c an inspector told us there was an issue. Anyone have any thoughts?

Did anyone ever figure out what this was? Having a similar problem.