Ok I have looked at several threads already and done quite a bit of troubleshooting on my own and haven't gotten anywhere.

It started with my dog chewing the thermostat wires that go to the A/C unit. He chewed completely through both in one spot so I twisted them together to make a temporary fix until I could get replacement wire. Switched on Thermostat and the A/C ran like normal. So I then switched it back off and wrapped up the chewed parts with electrical tape. After I did this the A/C unit would not come on. I'm thinking that maybe I touched two bare wires together. I've looked closely and I am pretty sure that the wires are not touching.

I read that it could've shorted out the transformer, so I measured voltage between the two terminals and it showed about 18V (I believe it's supposed to be 24V). I also checked voltage where the power meets the door panel switch, it showed about 120 I believe and then followed the wire from that switch to the circuit board and it also registered 120V at the terminal there on the circuit board.

I checked the fuse on the circuit board and it is not blown. The red light on the circuit board never comes on though, but I don't remember it being on in the past (bad light maybe?).

So anyway, that's about where I am. Not sure what else to check. The thermostat still clicks when you set it to cool, or even when you set it to heat and then raise the temp above what the current temp is.

It's a Diamond York 80 system.

Thanks in advance.

You should be getting 28 volts from the transformer. Neither the outdoor unit or the fan inside works? Could be the t-stat.

you should be getting 28 volts from the transformer. neither the outdoor unit or the fan inside works? Could be the t-stat.

Neither outdoor unit or blower is working. How do you check thermostat? It's a White Rogers digital. It clicks when you have it on hot or cool and set temp above or below current temp.

Take the t-stat off and jump between r and y for cooling and r to w for heat. But odds are it is your transformer.

take the t-stat off and jump between r and y for cooling and r to w for heat. But odds are it is your transformer.

Do you suspect transformer because the voltage at the terminals is 18 instead of 24?

Yes it should be 28 volts but you can try r to y to make sure it is not the stat

yes it should be 28 volts but you can try r to y to make sure it is not the stat


All right will do when I get home this afternoon.

Thanks for your help. I'll report back.

OK I should be on later if you need more help.

Turned out to be the transformer. A friend of mine who does HVAC came over and swapped it out. Thanks for your all's help.