Couple of youse have mentioned the float switch as a possible cause for blank thermostat display panel. Yeah, I have had that in the past, so of course I checked that and the drain area where the float switch lives, is bone dry. This is definitely associated with the power surge from the lightning hit.

HRK suggested grabbing a window unit for temporary relief. Unfortunately, the only window in our bedroom is a full size sliding patio door, so no practical way to use a window unit.

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Added: Just did the voltage check per SigMonkey's post on previous page. Thermostat is not getting 24 volts across R and C wires, so next thing to check is the fuse or circuit breaker in the air handler. Should be simple enough, but 89, with mobility limitations, that is beyond my physical ability, so I need to get an HVAC tech here. I have reached out, but no response yet.

quote:

Originally posted by RogueJSK:
On the motherboard of the main air handler unit, which is likely in your attic.

It protects the low voltage circuit that powers the thermostat.

The board will be under an access panel or removable body panel on the main unit, and will look something like this, with an automotive-style blade fuse with the amperage printed on top. (Usually 3A or 5A)

Shut power off to the unit, replace the fuse with the same rated fuse either from the spare fuses in your car or from the auto parts store, then power it back on and see if that corrects your issue. If it blows again, you have deeper issues, like a wiring short.

Rouge is almost certainly right, this fuse blew during the lightning strike. It's the circuit board in your furnace. Easy, cheap fix.

I continue to discover things that were damaged by the lightning-induced power surge.

Garage door guy was here today to replace the fried circuit board in the garage door opener. Re-synced the remotes, the outside keypad, and the built-in car buttons.

He is not an HVAC guy, but he took a look at the air handler. No circuit board in there, it's old-fashioned discrete components wired together. The automotive type fuse was blown, just as some of youse suggested. He inserted a new fuse, which blew instantly; we agreed that it's time for a professional.

Fortunately, "Garage Door Phil" has a good friend, "Air Conditioning Joe," who, it turns out, lives about ten minutes from me. Joe couldn't make it today, but he said he will be here tomorrow, around mid-day. Whoo hoo!

Now to determine whether the TiVo DVR is a dead doggie, or can be revived; my wife is the TV watcher in the family and she loves that TiVo. I'll get a replacement for her if this one can not be resurrected.

Would lightning rods prevent such problems? When I was a boy in Missouri they were commonly used to protect buildings from lightning damage.

Get thee an SPD - Whole House 'Surge Protection Device' --> https://www.eaton.com/us/en-us...urge-protection.html

What a coincidence. My hvac stopped working today. Got to 90F before I noticed. Had to replace the batteries in the thermostat and clean the leads of some corrosion. All working again. The hits keep coming at our house.

"Air Conditioning Joe" was here yesterday. Couple hours of painstaking diagnosis found that the C wire was shorted to ground somewhere between the air handler and the thermostat, causing instant blow of fuses, as soon as they were inserted. Disconnected C wire at both ends, found an unused (spare) wire in the bundle, and connected it in place of the C wire.

Next step in diagnosis found that the C wire short had fried the thermostat. Joe went off to get a replacement; the model that we had was not available, so he got the closest replacement, Honeywell X2S which met my specification for the simplest, least expensive, thermostat that offered programming and WiFi and would accommodate the heat pump system that we have.

New thermostat installed, refrigerant topped off (3 pounds) and Bob's Your Uncle.

Total outlay to date for garage door opener circuit board replacement, air conditioner restoration, and payment for inspecting and resetting main breaker, to electrician who lives down the street, $1,176.50, and counting, as new problems are discovered.

Waiting for reply from service department at WeakNees.com, re TiVo, which seems to be DOA.

Re nhracecraft's suggestion, we will check with our friendly neighborhood electrician re whole house surge protector.

Friendly tip as I had a strike a few years back. I kept finding damaged and failed electronics for about a week after my initial strike. Some of it died right away, other things died several days/a week later.

If you plan on filing any kind of insurance claim, give it another week before you make a list.

This is the SPD I bought:
https://www.amazon.com/dp/B01A...t_b_fed_asin_title_3