What is the everyday resistance of the coil where on earth the 24vac within the contactor of internal ac read? central ac contactor doesn't kick contained by. 24vac is not there but...
central ac contactor doesn't kick contained by. 24vac is not there but ok at the transformer side. could be open between the red-wht occupancy?
Answers: Your contactor should get power from the Y terminal. On a call for cooling, you should read zilch from R-Y (it's a closed circuit), you should read nothing from Y-one side of contactor coil, you should read 24 volts from Y-other side of coil. If you read 24 volts from Y-either side of coil, you probably have an amenable pressure switch, which are usually put in series with contactor. The glorious pressure switches often have a encyclopaedia reset button. If you have a Carrier unit, they usually enjoy a compressor logic board ahead of the contactor. You can identify it because one of the compressor leads will snake through a small rings on the board. That can be reset by cycling the power off to the board, any through the thermostat or the disconnect switch. The coil resistance is normally pretty low (20 ohms or less). If it fails, you'll probably newly read an open circuit through the coil with an ohmmeter.
If this is a behind model furnace look on the control board for a 3 amp fuse just like the one you use contained by a car. That is where your problem lies. Go to the local auto store receive a box of fuses. Before you do anything else check the wires going outside (red and white and make certain neither are touching anything and their insulation is righteous. If so then replace the fuse and see if it comes on. You either enjoy a low voltage fuse prbllem, a control wire going out side failure or a unpromising t stat