<p>Got off the 5th meeting of the day around 4 PM and got a voice message from DW: please call home right way. It turned out, the A/C is out at house and the temperature is raising fast. We happen to have a houseguest.</p>
<p>I got home around 5 PM and started checking on the system. Fuse to the condenser unit and A/C unit breaker are all o.k. Between the online DIY sites and the owners manual, I found out there is no power to the old thermostat. From there, I found no power to the transformer. Long story short, after about 30 minutes of going back and forth checking, I found the problem. The previous owner apparently installed a switch by the doorway to turn the whole A/C unit off. Somehow one of kids turned that switch off, as it was a light switch. </p>
<p>You got lucky indeed. Unless the actual wiring was visible in a run in an unfinished basement or garage, it’s a good thing you found it. Kill switches on central AC units are not the norm, and when they are installed, they are normally at height 6 feet or so from the floor, much like attic fan and furnace kill switches. You might want to get a switch lock, available at most good hardware stores, or home center, or your local electrical suppy store.</p>
<p>Kudos to you. I’ve seen pros spend hours (sometimes days) tracing issues like this, and the solution often becomes replacing perfectly good parts in sequence in an attempt to remedy the problem.</p>
<p>I got no power to the thermostat, no power on the control unit on the blower, but everything o.o. from the breaker box, I kept think there is a problem on the wires in between. But we have a finished basement and tracing lines is almost impossible. </p>
<p>In any case, we have learnt so much about fixing things over the years. During the sales of our last house, the contractor asked for $3000 for all the repairs. Me and DW worked on it for two days and we got everything done with only $90 of materials.</p>
<p>If you can’t find a switch lock, like violadad suggests, you can get what we have on our furnace kill switch. It’s a thin metal arch that screws over the switch plate & covers the switch. You can’t accidently turn this switch on or off; you have to stick you finger under the metal arch to do so. The switch plate is also bright red with FURNACE written on it. Even my goofy son has never messed with this. I’d guess that this arch costs about $.17 or so & requires only a screwdriver for installation. My kind of home improvement.</p>
<p>laserbrother, you are, like, so lucky! When my AC went out last summer over the 4th of July weekend the day before we were scheduled to host a couple dozen of my in laws, I had to (a) replace the fan motor on the condenser unit (I did get lucky there - I got the last available unit in the county, and it was an easy bolt in 'n rewire job); (b) followed by replacing the fuses repeatedly until I realized that it was so hot that the combined impact of the heat bearing down on the AC’s fuse box and blowing up out of the condenser unit (condenser is, of course, on the south side of the house and right under the fuse box - brilliant design) that the combined heat and amp load was blowing them every ten minutes, so I had to (c) get and install a 100 amp circuit breaker (less susceptible to heat-trips) in a new box (of course the old one wasn’t the right size and shape) and get it all up and running the evening before the guests arrived.</p>
<p>Did I tell you I had to do all that work in the mid-day sun on a 108 degree day in the heat reflected off the south wall of my house? DIY can kiss my $#@&^!%&$#&^!!!</p>
<p>Oh, wow, I am jealous, I would have just panicked and paid my AC contractor the standard $6,000. Seriously did, too, a couple of years ago, after he told me that the coil had a leak in it somewhere (apparently there is no way to even FIND a leak in a coil, let alone fix it).</p>
<p>I am not businessman. I am just an experienced technical person.</p>
<p>For a long while, I was contented with just being able to change oil and air filter on my car. That totally changed, when I purchased, on impulse, a low mileage 1991 560 SEL. Facing with $100/hour labor and sky-high part cost, I decided that it is time to get my hands dirty. Within the two years I owned that piece of junk, I saved myself at least $4000 on repair cost. What is more important, I have now tools and the attitude that I can fix anything – mechanical that is. </p>
<p>I have fixed our washing machine; microwave oven; install a new kitchen for my parents, among many things. I even figured out how to repair a three-way switch, which was in the loop of another three way and a four way. </p>
<p>Of course, I also have several “bad” DIY stories.</p>
<p>My DH does electrical! But he draws the line at plumbing. In our first house we redid the (very small) kitchen by ourselves. A professional did all the plumbing, however. </p>
<p>Ah, those were the days. The kind of house it is impossible to make WORSE by DIY.</p>