This is not directly related to AM per se, but it applies to QRO, whether it is a ham rig, A/C system, etc. When I returned home on Sunday, things were quite warm, both inside and outside. I expected around 78f inside, not 94f! At first, I thought I had a problem with the A/C thermostat. Previously I have had trouble with the five-minute short-cycle safety that is built in. A weak battery makes this feature erratic. I was troubleshooting an intermittent problem, as the outside compressor/condenser/fan operation was erratic. But monitoring the relay voltage indicated the problem was outside. Opened it up, and found severely burned contacts in the main contactor. Replaced that, and thought all is well, it worked for a while. Then cooling discontinued, but it appeared everything was getting power. The condenser fan still running, but no compressor. Suspecting the capacitor (2 section, one for fan, one for compressor) I decided to disconnect the wires and test it. After switching off the disconnect, I still had 120 volts from ground to each leg. But no 240 between the legs. It turns out the disconnect, an old bread-slicer switch, failed mechanically, in that one of the swinging switch poles disconnected from the shut-off lever assembly, so one side of the 240 volt line was still connected. I attached a couple photos at slightly different angles to illustrate the failure mode. You can see the switch blade on the left is still connected at the top. while the right blade is properly disconnected. The fibre link on the left has failed, and no longer moves with the switch lever. I ALWAYS check with a meter before touching anything, I NEVER trust a breaker or disconnect. It only takes a few seconds! I must go off and get a safe disconnect switch and install it before I can proceed. I really like the version where you actually remove a plug instead of a knife switch or a breaker, but those are hard to find. It is 97f and the mosquitos are predominant. No fun in river city today.