Home A/C Troubleshooting After Lightning Strike?

The transformer on the pole in front of our house was struck by lightning last night. Smoke, sparks, the whole show. It was lovely.

Now that we have power back, everything seems to be working fine (computers, TV, etc etc.).

Except the air-conditioning. Here's what the Nest thermostat is saying, no power to the Rh wire:

I checked the breakers, and it feels like I'm unable to really reset the (really old) 30 amp breaker labeled "heat" that may or may not actually power the heat. These are definitely the HVAC system breakers, but the labels are from 2-3 systems ago.

Should I just put a new set of breakers in and hope that fixes the "no power to the system" issue? Or is there another initial diagnostic step I should take?

Oh, and I did check the float switch. Condensate pump has no power (dehumidifier filled it to the point of overflowing and it didn't kick on) but the float switch is in the safe position.

I'm not a HVAC tech but I've paid for a few to check our system.  After a few installations there may be additional breakers/switches in the circuit.  Locate and check them as well.  Last time ours went out it was a breaker at the air handler that had perished, a further check by the technician revealed a bad switch in the outdoor box disconnect as well.  I found the air handler problem, didn't catch the disconnect issue.  TL.DR.  Just call the HVAC guy..

Yeah, air handler breaker is fine, but good point about the outdoor disconnect... I'll investigate that next. I think I accidentally bought and installed a fused version a few years back, so that could be my problem.

Call a good HVAC guy, and then call your insurance company. Ours were replaced for our deductible after lightning took them both out. In both cases it was our compressors, they had seized and are nonservicable. Welded shut. I paid $1000 and got two new A/C units.

Success! Just a bad breaker; after some trial and error with a multimeter, I managed to get it reset and the temperature is dropping. I'll add that to the list for my next Lowe's run.

Thanks for the help, everybody!

Glad you fixed it. 

Next time, you can swap the other tandem breaker on the other side to test. Looked like a 30a as well.