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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8443
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My dog chewed the low voltage wires running from house to

Customer Question

My dog chewed the low voltage wires running from house to outside unit. Inside furnace/blower was running fine on heat, but on cool, was not cooling, this led me to discover the chewed wires. While splicing them together I noticed a slight spark where low voltage wire went into unit side. I removed cover and discovered that one of the wire caps connecting the low voltage wires to the outside unit had come loose and bare wire was touching side of unit. I removed outside fuses and completed splice. Once I completed splice, I replaced outside fuse and went to test. Now, nothing comes on at all, no furnace, air, fan, nothing. I have checked all breakers and all seems to be on. I have not looked for a reset button on unit yet, but would that affect the inside furnace/blower? I have not looked in site glass on furnace/blower to see if there is a flashing light to indicate power. What could cause this?
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


You have most likely blown a 3 to 5 amp rated fuse at the 24 volt transformer in the furnace, or in the printed circuit card in the furnace.

Please attach a well focused, close up photo of the wiring diagram glued inside the service panel,you can use the paper clip icon at the right end of the toolbar at the top of this dialog box,Include a picture of the thermostat wire connections to the printed circuit board in the same area.

If there is no paper clip icon, look for the '+attach files' link at left of your send button.

I can mark it up with trouble shooting instructions. You will need a multi meter ($30 at a hardware store) and some experience working with appliances, let me know a lot about your skill sets in those regards.

We can go from there.