Download or read book Troubleshooting and Diagnosing HVAC Most Common Problems written by Gregory Marcellus and published by Collie Mckenzie. This book was released on 2020-05-25 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: If you do not have 24 volts between Y and C then you either have a thermostat problem or a broken thermostat wire problem. You would need to keep checking for 24 volts between the Y and C wires. Where you stop getting the 24 volts is where the problem is located. How can I detect if the cause of the problem is low pressures (refrigerant charge) and not something like short circuits or other things? Without measuring the pressure is it possible to find out for sure that the safety control is the reason I don’t have 24 on my contactor? Without gauges, it is a guess. If I did not have gauges I would turn both the high voltage and low voltage power off to your unit, cut the two wires that go into the low-pressure switch, strip the wires back, and join the two wires together with a wire nut. Make sure that you leave enough wires sticking out of the low-pressure switch so you can reattach the wires after this test.