Problem: My Air conditioner’s contactor will not engage. I am not getting 24 volts to the contactor to make it engage? What could be the problem?
Answer: If the contactor is not getting the 24 volts to the contactor coil then it could be a time delay relay (if the unit is equipped), thermostat problem, transformer problem, safety control, (low on refrigerate) wiring problem, or a condensate pump, secondary drain pan safety switch problem. If you have a safety over-flow switch on your condensate pump or secondary drain pan then if you condensate pump is not working or if the secondary drain pan is full of water then this would cause the contactor to not get 24 volts to make it engage. I would suggest that if you do have a condensate pump that you check to make sure it is working. I would also suggest that you turn off the power to the unit and check your connections to make sure all connections are good and tight. I would also suggest that you test the contactor with a voltmeter to see if you are getting the needed 24 to 28 volts AC on the contactor coil. This could also be a blown fuse on your furnace or air handler control board. If the fuse on your control board is blown then you probably have a short in the thermostat wires or another control in the furnace or outdoor unit. This could also be a time delay relay problem. We sell a universal time delay relay on the following page: Please click here if you would like to see the time delay relay we sell. We sell transformers on the following page: Please click here if you are interested in seeing the low voltage transformers we sell. Many air conditioners and heat pumps have low and high-pressure safety switches on them to protect the unit from damage if the system pressure is too low (low refrigerant charge) or too high (dirty outdoor unit or slow or bad condenser fan motor). If your unit is low on charge (I find most often) the safety switch will not allow the unit to start (contactor will not engage). You will need to call a service tech in order to check the charge on your unit. We sell contactors on the following page: Please click here if you are interested in seeing the contactors we sell. Please send us your unit’s model number if you would like for us to find out and see which OEM contactor or parts your unit requires. Our email address is: email@example.com Below we have a real informative YouTube video made by grayfurnace man which shows how to troubleshoot and test a contactor. We have other troubleshooting links on the following page: Please click here if you would like to see our other troubleshooting pages. If you have any questions we will be glad to answer them. Please email us: firstname.lastname@example.org or comment in our comments section below. We would love to help you out and have your business!