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Blog Title: what is 24 volts on the connector of an air conditioner.

Main Que: Why I am not getting 24 volts to the contactor? Where does the 24 volts come from?

  • Category:
  • Query By: SHERRI GARNER (Washington Navy Yard, MN)
  • Date: 09/01/2014

Answer: The 24 volts comes from the transformer. We sell transformers on the following page: Most of the time the transformer is located inside the furnace, although sometimes (about 10%) it is located inside the outdoor AC unit. The transformer produces the 24 volts which goes up to your thermostat then out to your air conditioning unit when the thermostat calls for cooling. You should try to turn the thermostat down so the air conditioner is supposed to come on. Pull your high voltage disconnect so there isn’t a chance of you getting shocked. Test with a volt meter set to “Volts AC” and see if you are getting 24 volts straight out of the thermostat wires that come into your outdoor AC unit. There should be two thermostat wires that go into your AC unit. If you are getting 24 volts then probably one of your safety controls on your air conditioner is not allowing the contactor to kick in. A lot of the time air conditioning units have both high and low pressure (low refrigerant) switches on them. If you do not have enough Freon (refrigerant) in the system it will not allow the unit to come on. If you aren’t getting 24 volts straight out of the thermostat wires, then you could have a thermostat, transformer or wiring problem.

  • Replied By: SHARON WHITE (Royse City, MI)
  • Replied Date: 09/10/2014