A/C Disconnect no Fuses

I found a couple of similar posts but they were very old and didn’t answer my specific question.

So we recently moved into our new home and I decided to toss a programmable thermostat on the wall in place of the manual Honeywell one. I diligently photographed the previous wiring block on the existing Honeywell, but during the course of re-wiring it my 7 year old was nagging me and I accidentally miswired it. The old block had a blue wire under “C” and I accidentally put this under “B”. I didn’t notice this right away though.

The A/C worked fine through the night, but come morning time when I needed to turn the heat on I flipped it over to heat, the relay clicked, but there was no fan or any other sounds. There’s not a long delay to this thermostat, maybe only 5 seconds.

I pulled it off and compared to my picture of the old one and noticed my mistake. I re-wired it correctly (putting the blue wire back under “C”) but that didn’t get it working.

I checked the breaker panel, everything is “ON”. I flipped the Heat and AC breakers to OFF and pulled out the quick disconnect labeled “Wadsworth - Pull out to renew fuses” and much to my surprise there’s just two large copper bus bars in this thing with no fuses.

So with all of that said, my question is where should I look next? Is there likely to be a fuse inside the AC unit itself? I’m also curious if this mistake could have cost us our lives…and why the damn disconnect doesn’t have fuses…:shock:

The disconnect is to “disconnect”. It is not an OCPD.

Your wiring job short circuited the thermostat.

  1. You blew the thermostat.
  2. You blew the transformer Hi Voltage side.
  3. You blew a transformer fuse (if you lucky enough to have on in the unit).

If this was a fused disconnect and someone used copper pipe instead of the fuses it was incorrect. Replace the pipe with the proper size fuses or replace the disconnect with a pullout style unless the unit specifically calls for fuse protection.

Sounded to me it was one of these: