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CarlosW · Sep 25, 2009, 10:58 AM

Hi, my a/c keeps going out. I have changed the transformer twice because it keeps shorting out and blowing them. The thermostat keeps going out (digital). It seems that it is not calling for the unit to come on. What could this be? :(

What would cause the transformer to shortage out?

Clough · Sep 25, 2009, 11:57 AM

Greetings and WELCOME to the site, CarlosW!

I moved your question out of Introductions to this forum topic area so that it will be more likely to be noticed and addressed by those who are best able to answer it. Your question will get noticed much more here.

Introductions is for people to introduce themselves only, and we try to not ask questions there. We would appreciate it if you would return to Introductions sometime to tell us a little bit about yourself, if you would be willing to do that.

Thanks!

CarlosW · Sep 25, 2009, 03:05 PM

Thanks

hvac1000 · Sep 25, 2009, 03:09 PM

Have you changed anything in your system lately like the thermostat or other item before the problem started?

Have you checked the low voltage wiring oiutside for damage? Sometimes animals will chew the small cable and cause a short.

Post back with the answers to these questions.

CarlosW · Sep 25, 2009, 05:37 PM

Hi,
Thanks for responding. No, I have not replaced anything but when it happened the first time in June, we got a new thermostat. But it still did not call. So then we found it was the transformer. So we replaced that. But we put the old thermostat back up. It worked up until now. One day I looked up and the thermostat was blank again. So that is when he got another transformer and put it in. Then it shorted. So he got another one and it blew it out again. So now he got another one and that one started to short after a few minutes of watching it so he turned it off. But he also put in a larger thing in the breaker box thinking that would help. Now he is thinking that it was not large enough and he needs to go get a bigger on that will take a larger current or whatever. :)

hvac1000 · Sep 25, 2009, 06:10 PM

Check out this link below. Transformer problems have been discussed on this board many times

https://www.askmehelpdesk.com/heatin...ns-280435.html

You might pay special attention to the part about adding a fuse to the circuit so you stop burning out expensive transformers until you find the problem. In my past dealings with this type of problem it is usually a shorted low voltage wire that is causing the problem. It can be located anywhere along the low voltage wiring. Thermostat connections or the wires behind the wall or where the wires go to the inside unit. The wires also go to the outside unit so I would check all of them for damage.

It is easy to do. First label all wires at the furnace then disconnect them. Turn on unit and see if the fuse you installed blows. If not then put back the wires and go to the outside unit and label and remove those low voltage wires and test the same way. This way you can narrow down the problem. Post back with the results of your testing. NOTE: There has to be a short circuit somewhere for the transformers to burn up IF you are wiring the replacement transformers correctly.

NorthernHeat · Sep 25, 2009, 06:11 PM

I've seen contactors cause this problem but it is more likely the thermostat wire to the outdoor unit as HVAC1000 suggests. It may just be a nick right at the aluminum siding or some other similar location causing the problem to be so intermitant. Fuse protect transformer with a 3 amp inline fuse and save x-former

CarlosW · Sep 25, 2009, 08:48 PM

Thanks all. We will try both. Very appreciative.