By August 10, 2009

What’s this switch do?

About a month and a half ago I left for Georgia on vacation. My friend Grizzly Adams stayed here at the house to watch the dogs and keep an eye on the premises. When I came back, the upstairs was 78°F. The downstairs was 72°F and the air conditioning was running full-speed. Normally I keep the house at 68 – 72° at all times, and I have separate air conditioner units for each floor. I have a home owner’s warranty on the house (they replaced my upstairs unit already), but I was tired and wanted to go to sleep with cool air blowing through the house. I reset the breakers, waited awhile, and turned the unit back on. Everything seemed cool.

The bottom level, however, was always humid. Noticeably humid, to the point it was curling paper and playing cards. I put one of my thermometers down there and although the temperature was correct (69°F), the humidity was around 72% — over 20% higher than the upstairs. I put in a call to my home warranty company right before a second trip to Georgia. The technician came out and was stumped. He refilled the coolant on the downstairs unit, stating it was unlikely this would fix the issue but that was the most obvious thing he could do. I paid my $85 deductible for over $200 worth of coolant, so that seemed like a good first step to me.

It worked — barely. The humidity went down to 70%. Not good enough. I called again when I returned home from New York. Same fellow showed up, and this time he went underneath the house. Poor bastard. He returned with this:

http://gallery.drfaulken.com/d/7310-2/IMG_00041.JPG

Now, I run two filters inside the house, one for each unit. This is an internal filter on the air exchanger. It has never been changed or clean while I’ve lived here, and perhaps has never been serviced. He said I didn’t need it since I have one inside the house. He said it was so clogged that it created negative pressure in the drainage tube for the exchanger, and there was water all in the tube. He also cleared out one of the drainage plugs that had become blocked.

A day or two passed but it wasn’t much better. I decided to look at my thermostats for some reason. I hardly ever fiddle with them, as the house stays the same temperature all year round. I noticed, this time, that the upstairs unit had the fan switch set to “AUTO” and the downstairs switch was set to “ON.” I flipped the downstairs switch to “AUTO” and within a half hour I could feel a difference. The downstairs humidity is now a more pleasant 53%.

Perhaps Grizzly Adams set the switch when the AC was on the fritz in May, thinking that it would blow more air downstairs and keep things cooler. I can’t believe that neither I nor the technician failed to notice that the switch was set to “ON.” He even looked at the thermostat each time he visited. I am glad that things are better now, and that I got some more coolant out of the whole affair.

Bottom line: Occam’s Razor applies to more than just science, and often the most simple answer is the correct one.

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1 Comment on "What’s this switch do?"

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  1. Gremlin says:

    I’m not sure I agree with his assessment that you don’t need that filter. If you didn’t need it, how did it get so dirty? The whole change the coolant thing is a complete crock, you got taken, less badly than if you hadn’t had a warranty. A basic temp drop test would tell him that he had low airflow across the coil. I wonder about the drain on your unit, if the pan is retaining water, which it is or the constant fan wouldn’t keep your humidity high. I’d take a look at that pan again to see why it isn’t drain properly.

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