We encountered a situation where our HVAC system was overcooling at the evaporator unit, tripping the DATS low limit, and short cycling the compressor. Improving air flow in the air handler has solved it, but I’m looking for a way to monitor things over time to make sure it doesn’t happen again (this was overnight and our compressor unit is too far from the bedroom to hear it). The poor thing cycled all night and never hit the target temp.
One option is a vibration sensor stuck to the compressor itself. This feels kind of low tech, though it would also show that the compressor is actually running, so that’s a plus. I can get outdoor magnetic covers for the aqara vibration sensors on Etsy.
A more electrically-minded solution I thought of is a 24VAC relay across Y/C at the air handler, and then running the normally open terminals across an Aqara water sensor (so I don’t have to do any disassembly or soldering). When the controller starts or stops the compressor, the relay will switch the Aqara sensor on/off accordingly and I can monitor this in HA.
I could either look at number of cycles in a recent time period (e.g., more than 3-4 cycles in an hour would be concerning) or have an alert if there is no signal on Y while the thermostat is calling for cooling.
Just throwing this out to see if anyone has done something similar or has any thoughts. I know there are fairly sophisticated HVAC systems people have developed here, and I’m not looking for anything that complex; just literally monitoring those two wires for the presence of 24VAC.