The air conditioner cooling our living/dining area is mounted (no other place to put it) in a south-facing window. At the peak heat of the day it is directly in the sun, and frequently cuts off due to overheating. Is hosing the coils with water to help them shed heat a good idea, or is it likely to do terrible irrepairable things to our air conditioner?
Could you put some kind of reflective material around it on the outside without blocking it’s airflow instead?
Most modern window AC units do exactly what you propose, internally: Instead of allowing condensate water to simply drain out the back it’s allowed to pool in a reservoir pan and a special blade called a slinger attached to the exhaust fan flings it onto the condenser coils. I don’t think spraying a small amount of water on the coils will hurt it.
Also, pop the plastic cover off the front and check the entire air intake surface, and clean the filter in front of it.
If the filter is very clean, and there’s no ice on the surface at all, that helps it to work less hard.
A couple years ago, ours was shutting off at peak times when we needed it to work. We thought it was overheating too (it probably was), but when we popped the plastic cover in the front, the air intake filter was dirty, and the whole radiator-looking assembly was covered with ice. That caused the motors to have to work harder, which eventually caused it to shut down.
We cleaned the filter, melted the ice, and started it up -works fine now.
Spraying water on the condenser coils is done quite often in commercial retail refrigeration, or was in the late 80s when I worked at a supermarket. On really hot days, we’d turn on a valve, which would mist the condensor coils for the store’s refrigeration systems. It was the only way to keep the frozen foods at the low freezing temperatures it needed.
If somone didn’t turn it on when they needed to, you’d start seeing soft ice cream by about noon.
Spraying the condenser coils with water is definitely going to lower the head pressure and keep the unit from overheating. That said, it’s best done sparingly, because unless your water supply is composed of pure distilled water, spraying your coils will deteriorate them*. Granted, it takes awhile, but it happens. The other problem is with mineral buildup from the evaporating water interfering with heat transfer. Again, this takes time.
The best thing you can do is make sure that your condenser and evaporator coils are as clean as possible for maximum heat transfer. The amount of heat added to your condenser from the sun shining on it is negligible in comparison to the amount of heat that it is removing from your room.
*Full disclosure - I spray my A/C condenser with the water hose every time I am in the vicinity and I have yet to notice a problem. OTOH, I saw a commercial building where the maintenance crew had set up a sprinkler system on the roof to spray the condensers to keep the units online during hot summer months. After three years of this, all of the units had to be replaced because the aluminum fins on the coils had turned to mush and were completely blocking the airflow.
Can you prop an umbrella or some other shade over it?
I was advised recently by an HVAC guy to take my garden hose out to the A/C unit outside my house and “spray the coils off”.
I also change my filter every one-two months. It makes a huge difference.
I wondered upthread if the window unit could be shielded from the Sun’s rays by a reflective material, thinking as the OP did that somehow direct sunlight was affecting the operation of his a/c. I see now that the rays of the Sun and the operation of the a/c unit are not related.
Right?