I know my way around central heating and basic plumbing, but I have very little experience with air con prior to coming to Thailand, so I'm still trying to figure this out. We have three air con units, and the one downstairs sometimes smells musty. I clean the removable filters inside regularly. We get them professionally cleaned every 6 months (landlord pays once, we pay once). Sometimes when they are due to be cleaned, one of the units upstairs gets a little musty, but that clears up as soon as it's done. 

The one downstairs, which we use most, is less predictable.  It was cleaned about 2.5 months ago, and it already smells musty, and worse than ever.  The box outside (condenser coil?) gets covered with dirt and dust quickly, within a few weeks of being cleaned. I brush what I can off the box outside, but I can't reach it easily. Can I just hose it down to clear more of the dust off? Google says you can, but it sounds like a terrible idea to be spraying water at an electrical unit. ???? 

Should I be getting them professionally cleaned more regularly? Is there anything else I can do in terms of routine cleaning and maintenance? Or is just the inevitable result of running air con in a dirty polluted city?

3 minutes ago, Polar Bear said:

I know my way around central heating and basic plumbing, but I have very little experience with air con prior to coming to Thailand, so I'm still trying to figure this out. We have three air con units, and the one downstairs sometimes smells musty. I clean the removable filters inside regularly. We get them professionally cleaned every 6 months (landlord pays once, we pay once). Sometimes when they are due to be cleaned, one of the units upstairs gets a little musty, but that clears up as soon as it's done. 

The one downstairs, which we use most, is less predictable.  It was cleaned about 2.5 months ago, and it already smells musty, and worse than ever.  The box outside (condenser coil?) gets covered with dirt and dust quickly, within a few weeks of being cleaned. I brush what I can off the box outside, but I can't reach it easily. Can I just hose it down to clear more of the dust off? Google says you can, but it sounds like a terrible idea to be spraying water at an electrical unit. ???? 

Should I be getting them professionally cleaned more regularly? Is there anything else I can do in terms of routine cleaning and maintenance? Or is just the inevitable result of running air con in a dirty polluted city?

The musty smell must be from the water generated in the A/C, turn the A/C on, go outside and make sure the water is being drained properly. The drain pipe should be near the outside unit..

 

Make sure the room is ventilated at times to remove lingering moisture in the air.

You can buy a spray to kill off the bacteria inside the unit, the smell..

I'll look for the spray. Do you have any recommendations or are they all much the same? 

We leave the windows open in the mornings with a fan, and then switch to AC around midday. 

The water just drips out of the bottom of the unit outside. All 3 of them do that. There are what look like condensate pipes, but the plumbing for them is so utterly ridiculous that I doubt they ever worked. (I put potted plants under the drip to stop algae growing.) 

3 hours ago, Polar Bear said:

Can I just hose it down to clear more of the dust off? Google says you can, but it sounds like a terrible idea to be spraying water at an electrical unit. ???? 

You absolutely can, just make sure they are turned off before you start, it can take almost 10 minutes before the water runs clear.

13 minutes ago, sometimewoodworker said:

You absolutely can, just make sure they are turned off before you start, it can take almost 10 minutes before the water runs clear.

There is an individual breaker switch for it indoors (an actual switch, not just the breaker box). Will that turn the outdoor part off as well, or is it more likely to have its own electrical supply? I couldn't see an obvious connection, but I don't know how to tell if the outdoor box has been isolated if the part inside has been turned off. 

4 minutes ago, Polar Bear said:

There is an individual breaker switch for it indoors (an actual switch, not just the breaker box). Will that turn the outdoor part off as well, or is it more likely to have its own electrical supply? I couldn't see an obvious connection, but I don't know how to tell if the outdoor box has been isolated if the part inside has been turned off. 

On mine the indoor and outdoor units are fed from the indoor one, the switch feed goes to the indoor one....

As someone else pointed out, it is likely not draining correctly/completely. Make sure the drain-pipe is clear, and the evaporator is installed such that it drains completely. 

 

Running the unit in "Fan" mode for an hour or two now and then helps a lot. 

16 minutes ago, Yellowtail said:

As someone else pointed out, it is likely not draining correctly/completely. Make sure the drain-pipe is clear, and the evaporator is installed such that it drains completely. 

 

Running the unit in "Fan" mode for an hour or two now and then helps a lot. 

+1 on the "not draining correctly".  On the indoor section(s) of my split units, the drain hoses were plumbed in about 1/4" above the bottom of the drip pan so I always had about 1/4" of standing water in the drip pans.  I had to feel around to figure out there was always water in them.  

1 minute ago, impulse said:

+1 on the "not draining correctly".  On the indoor section(s) of my split units, the drain hoses were plumbed in about 1/4" above the bottom of the drip pan so I always had about 1/4" of standing water in the drip pans.  I had to feel around to figure out there was always water in them.  

On mine the water catch tray has 2 outlets, the fitter can choose the best one for his fitting location and use the rubber bung to seal the spare one off.

 

Problem is, the spare one has a well where the water in it is always there, so on mine I used silicone sealer to block the channel feeding it, job done.

 

On another they had not installed it level, plus the drain pipe was kinked, so though not a lot out, but enough for water to lay in the tray, a bit of fiddling around did the job..  ????