Looks like I can add garbage disposals to the ever-lengthening list of household appliances that I can take apart, fix, and put back together.
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.5
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.6
- 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. ↩
- Does this help? ;-) ↩
- But I don’t have forever; the heat doesn’t work either. ↩
Our HVAC stopped working in the hottest week of the summer (so far…). Rather than call an HVAC tech, I’m trying to fix it myself.1
Symptoms: no fans start running even though thermostat is correctly set (and for that matter, fan set to “on”).
Checks so far:
- Thermostat batteries
- Short yellow to red and wait two minutes
- Interrupter by condensor
- Look for fuses in furnace control circuit and interrupter (there were none)
At this point, I think it’s time to verify voltages and signals, starting with the transformer and furnace control circuit, then moving outside to the condensor.
Wish me luck!