my compressor outside is not kicking in. Here's the sequence of events:
- I came home and the thermostat – a Honeywell LCD – was no more numbers and the battery indicator was flashing.
- replaced the batteries and no change in that
- bought a new basic thermostat and hooked up the wires correctly – note there is a Green, White, Red and Yellow wire and the hookup locations are very obvious
- installed the thermostat face, and all controls behave as expected, and the cooling shows as being on – but the compressor outside is not kicking in.
It's possible I crossed some wires? but I don't think so. I know years ago someone replaced a capacitor on my compressor but I've had no problems since then. How would I troubleshoot this?
Best Answer
Test the thermostat
There's a couple ways to do this, the "professional" way, or the "caveman" way.
Y
terminal on the thermostat.R
terminal on the thermostat.Y
terminal on the thermostat.The meter should show continuity, and/or a low resistance. If not, the thermostat is bad, or not configured properly.
If the thermostat checked out, reinstall it and move to the next test.
Alternatively, a caveman would simply touch the "yellow" wire (the wire connected to the
Y
terminal) to the "red" wire (the wire connected to theR
terminal).This should turn on the A/C. If not, continue to the next test.
Test the wiring
WARNING: This test requires you to open up the furnace/air handler, and work on live equipment. If you do not feel comfortable, contact a local licensed HVAC technician. Next, you'll want to make sure the signal is getting to the furnace/air handler.
R
terminal.Y
terminal.Initially; when the thermostat is not calling for cooling, you should read about 24 volts. When the thermostat calls for cooling, that should drop to 0 (or very near 0, depending on how sensitive the meter is).
If this checks okay, move to the next test.
Test the contactor
WARNING: This test requires you to open up the condensing unit, and work on live equipment. If you do not feel comfortable, contact a local licensed HVAC technician.
If the unit does not come on, it's likely time to contact a local licensed HVAC technician.
If it does come on, move to the next step.
Test the contactor control wiring
For these tests, you can pull the disconnect for the condensing unit.
Initially you should read 0 volts. When the thermostat calls for cool, that should jump to about 24 volts.
If everything to this point tested okay, it's time to contact a local licensed HVAC technician.