First, I verified the 24V transformer’s primary is getting line voltage.3 Then, checking the secondary, I found no voltage. I tried again. I pulled it out of the furnace and tried again. Still no dice. I guess I could have just measured the impedance across the secondary and discovered the transformer was bad4 and needed replaced.
Unfortunately, by the time I discovered this, the local appliance parts and electrical supply stores were closed for the week. Home Depot and Lowe’s were still open but neither has a matching transformer. Looks like it will be next week before our HVAC is working.4
I’m concerned: if I replace the transformer, is something else wrong that will kill the new one? Or did the transformer just die of old age? I guess I’ll find out.
Fortunately, the weather is getting cooler.[^]
- Essentially, this is rule #1 of debugging: is it plugged in? ↩
- Ya gotta love the Transonics wiki’s disclaimer/warning/license: “The following information may have errors; It is not permissible to be read by anyone who has ever met a lawyer. Use is confined to Engineers with more than 370 course hours of electronic engineering for theoretical studies.” I’m still trying to figure out how this applies to me. ↩
- Yes, this means the breaker was ON and the furnace cover was off. If you’re thinking of using my post as a guide to debug your HVAC system, you should read the preceding footnote. ↩
- It was shorted. ↩ ↩