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Problem: My AC Unit Will Not Turn On or Run. What could be the problem?

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Problem: My AC unit or heat pump will not turn on or run. What could be the problem? Could you tell me how to get my air conditioner working again?

Answer: Many people have this problem where their air conditioner or heat pump will not turn on. The AC will not turn on. Nothing happens at the outdoor unit. We have a really good YouTube Video made by AC Service Tech LLC that explains the top 10 problems that are mostly found when an air conditioner or heat pump will not turn on.  I also have the 10 problems written down if you do not have time to watch the video. Thanks so very much to Craig Marciano for making this excellent video! Here is the list of the top 10 reasons why air conditioners or heat pumps will not turn on. If you have any questions please comment below or email us at arnoldservice@gmail.com We would love to try and help you out and earn your business!

*Always make sure that the electric power is turned off before working on an Air Conditioner or Heat Pump System. 

  1. No power at the contactor due to a blown fuse or circuit breaker being tripped. You should check the voltage at the outdoor unit’s contactor to see if you are getting voltage between L1 and L2 of the contactor. We sell a really good test meter on the following page. Please click here if you are interested in a really good testing Multimeter. We also have another really good meter on this page. 
  2. Bad power supply problem. You could have a bad or blown low voltage transformer or the power going to the transformer might be out. Please click here if you are interested in the transformers that we sell. 
  3. Having a bad capacitor. We sell over 80 different capacitors on the following page. Please click here if you are interested in the capacitor we sell. 
  4. The contacts on the contactor are burnt or bad. You might need a new contactor or clean the contactor. Please click here if you are interested in the contactors that we sell
  5. The unit might have a bad contactor coil. The video shows how to test the contactor coil.
  6. Might have a low-pressure switch that has electrically opened due to a low refrigerant charge, refrigerant leak. You would need to install gauges to see if your unit is low on refrigerant charge and find and fix the leak if the system is low on charge.
  7. You might have a bad thermostat connection from the indoor unit to the outdoor unit.  A weed eater or animal may have chewed through the wires or you might have loose wire connections at the unit, thermostat, or control board. You might have to run a new thermostat wire.
  8. The next 3 problems are when the indoor blower motor is not turning out so you have to focus your attention on the indoor unit.  The thermostat may look like it is on, but the indoor unit is off. Many thermostats are powered by batteries and this can give you a false visual feeling that the power is on, but really the power is not on. Make sure the power switch for the furnace is in the ON position and make sure the furnace blower door is latched tight.  Make sure the power on the breaker box to the furnace is turned on.
  9. Is that an emergency safety switch on the condensate pump or on the condensate over-flow float switch that has cut the low voltage power off to the furnace and thermostat.
  10. A bad thermostat wire, a bad thermostat, or a bad low voltage fuse on the control board.


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