I know I shouldn’t complain in southern California, considering how brutally cold it is back east, but we woke up this morning to a 63-degree house, and listening to a struggling furnace on the morning after the coldest night of the season to date. The blower seems to be on the fritz.

On a Sunday.

I had other plans today, but I’m going to have to take it apart, and see if I can fix it. It’s twelve years old. Hoping it’s just a bad capacitor. I doubt I’d be able to find a replacement motor today.

[Update a few minutes later]

Not really complaining, and have no right to. If we were back east right now, this would be life threatening, and we’d either have to get an emergency HVAC guy in, or find somewhere else to stay, but for us, it’s just an inconvenience. Worst case is extra blankets tonight, and I’ll find a replacement motor (or limit switch, or whatever the problem is) tomorrow.

But it’s also a reminder of how thin the veneer of modern technology can be, and that nature is not our friend. Whatever the climate is doing (and anyone who claims they can confidently predict it out decades is either fooling themselves, or attempting to fool us), we have to maintain enough societal wealth to deal with it. The policies promulgated by those who insist we can control the climate would have the opposite effect.

[Monday-morning update]

When we woke up this morning, temp in the house was 61 F. A couple hours later, it’s down to 60. It will probably warm up when the sun gets higher, but high temp today is only predicted to be 67.

In troubleshooting, I’ve learned two things: 1) Modern gas furnaces are complicated as copulation and 2) the burner isn’t lighting, which is why the blower motor isn’t bothering to. The status light isn’t flashing any of the error codes in the manual, just steady on, the way it’s supposed to if everything is copacetic, so it’s not useful for diagnostics. I’m suspecting the gas valve (a problem with which the control board would be unaware), but not sure how to tell if it’s working. Could also be the igniter, except I’d think I’d at least momentarily smell gas if that were the problem. Anyway, I’ve got to go start poking at things with a VOM.

[Update a few minutes later]

OK, I am briefly smelling gas when it tries to start up, so the valve seems to be working. Now suspecting igniter:

1. Remove burner compartment door to gain access to the ignitor.
2. Disconnect the ignitor from the Ignition Control.
3. Using an ohmmeter measure the resistance of the ignitor.
4. Ignitor cool should read between 40 to 75 ohms.
5. Reconnect ignitor.
6. Place unit in heating cycle, measure current draw of ignitor during preheat cycle. Should read approximately 4 to 4.5 amps.
7. If ignitor is receiving 115 Volts and will not light, replace.
8. After check and/or replacement of hot surface ignitor, reinstall burner compartment door and verify proper unit operation.

Supposed to be 40-75 ohmns, showing infinite. That seems like the problem. Looks like they’re about $20. Now to go out and find one.

[Update a while later]

OK, a replacement (and improved version) was $42 bucks. The old one had clearly failed; you could see the burn through in the element that had opened it up. It probably got hit by a piece of dust or something when it was hot. House is now warming up.

[Update a while later]

Temp is up to 64 degrees and rising. In retrospect, I would have saved time if I’d relied on Occam: If something isn’t igniting, first check to see if there’s ignition.

Further thoughts: Pilotless ignition saves fuel, and is probably more reliable, but if a pilot blows out, it doesn’t cost $40+ to relight it.

Anyway, I understand my furnace much better now. It was the first time since we had it installed a dozen years ago that I’d opened it up to see how it works.