Weird smell coming from A/C

I have single A/C wall units in each room of my house. Once they've been running for a certain amount of time (anywhere between 30 minutes and above) on a mid-level temperature (about 75F) they start emitting a bad smell. We cleaned all the filters (only to find they were pretty clean) and it didn't make much of a difference.
When they're running on a colder temperature (around 71-72) the smell is less frequent or non-existent. It happens pretty much every time they're used, but the time it takes for the smell to start varies. Any ideas what can be causing this and what can be done to rectify this?
q weird smell coming from a c, home maintenance repairs, hvac, This is the type of A C Not sure what the proper terminology is for it
This is the type of A/C. Not sure what the proper terminology is for it.
  14 answers
  • Shirley Shirley on Aug 31, 2015
    Have you ever taken the unit itself out and cleaned running water through can do need to sit it down at a slight the unit tilts the water will run out...of the pan under it...I am sure it is full of green yuck...wash it out good with your water hose...let it air dry for a little while..then put back in the cage...the unit should slide out easily..from the taking the front cover will take two people..I am sure..unless you are a strong person..if these are run a lot..this should be done twice a year...

  • Janet Pizaro Janet Pizaro on Aug 31, 2015
    It sounds like the inside of the unit has mild and or rust on it.I would take the unit out if possible and clean the inside out.

  • Larry Green Larry Green on Aug 31, 2015
    Remove the units in early spring and was thoroughly. I mean wash the two coils keeping water from the control panel and motor. Do this every year.

  • Lulu Dubin Lulu Dubin on Sep 01, 2015
    Thanks for the answers. I've now been able to add a photo to show what the A/C looks like. I'm not sure it was clear in the question and some of the answers suggest I remove it from the wall which seems to be almost impossible. This is the biggest one (in the living room). The others are about half the size, but it still seems strange to have to remove them since they're quite large and attached to the wall.

    • Adrian Adrian on Sep 01, 2015
      I recently bought one of these types of units and since it's new I have not had this problem. The only thing I can think of that would create a bad smell would be mold. The water line could be the issue but also if condensation has occured within the unit inside your home it could have also grown mold. You can't cover up mold, you have to kill it. Vinegar may help but Clorox Bleach would be your best bet. You can add straight Clorox Bleach to a spray bottle and dilute it just a bit with distilled water. Use only Clorox brand (not a store brand) and do not use tap water. The ratio should be about three to one meaning a mix of 3 cups bleach to one cup water. Protect EVERYTHING, your walls, flooring, furniture, clothing, etc. Spritz, let it drip and dry, spritz again and repeat this two or three times with unit off and unplugged of course. Check your water line to make sure it is clean and draining well. If it's possible to flush it with bleach be sure to flush it after with water. You can check to see if you can replace the water line hose if it's in bad shape. It's very important for these units to have a good clean water line hose to drain the water away from the unit. These units are attached to a bracket so you could remove it from the wall and take it outside although it would be a huge pain to do that. I wish you much luck and please let us know how things turn out.

  • Thesmell of mildew can literally develop overnight, especially during periods ofdamp and humid weather.Withregular attention and the occasional use of a few household staples, you canget rid of that mildew smell you hate so much, along with the hazardous,unhealthy mold those smells belong to.

  • Maura Maura on Sep 01, 2015
    I'm thinking if they can't be removed from the wall, maybe you could spray the inside with vinegar(unplug first and maybe an old rag to catch the vinegar dripping off) Otherwise call the manufacturer

  • Jan Herman Jan Herman on Sep 01, 2015
    Febreeze has a stick up thing that works in a car vent, maybe it would work here too?

  • Shirley Shirley on Sep 01, 2015
    I would be googling the brand..find out what I could about them...see if I could remove the filter..if they have filters..clean those...or the insides...if clean....that's where all the odors are emitting from....

  • Lisa B. Lisa B. on Sep 01, 2015
    They require routine chemical cleaning as well as filter replacement. Gunk can start to grow in the drain lines, etc. Best to call an air conditioning service company to come out and take a look. If its a chemical smell I would stop using them until a service person can come out and take a look at them.

  • 153091 153091 on Sep 01, 2015
    I just had to comment on this one! Never have seen one like this, and IF it has a pan inside for "drip" condensation, that must make the odor.There must be a way to clean it! Take Maura's the manufacturer.

  • Julia Sipe Bentley Julia Sipe Bentley on Sep 01, 2015
    My suggestion would be to unplug the system and then open it up as much as you can. You should be sure you are not dealing with any kind of mold...especially black mold. Regular cleaning and maintenance is a must with these systems to prevent molds from taking hold and dispersing in the air. Good luck :-)

  • Happyfeet Happyfeet on Sep 01, 2015
    We have those same exact units in the house we rent except yours look like they might not be made by the same manufacturer as ours. Do you have a remote control with yours? Because ours do and on it there is a button that says "air clean", you push that and it runs thru a cycle and shuts off by itself then seems to be ok after that.

  • Debbie Machmer Debbie Machmer on Sep 01, 2015
    I have window units and found several videos on youtube with detailed instructions on cleaning your own units. A can of coil spray was about $6. Worth the time.

  • Kag2215080 Kag2215080 on Sep 02, 2015
    If you bought the air units they must have come with a booklet, If you're like me I always loose mine or don't know where I put them, so my son always tells me to go to Google with name of product and serial number there you can find anything. they have the manuals that come with that air unit. on the internet.