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I am troubleshooting my home ac unit model GSX130361EC. It was not turning on with the contactor repeatedly clicking and the fan not turning, however trying to start then giving up. I had replaced the contactor and the capacitor on the unit since I had these parts on hand. When testing yesterday, it turned on and ran no problem. I went today and tested, and the unit will not start. It is not a blow fuse, I can manually depress the contactor and the unit starts. I verified all the measurements on the capacitor before installing. While researching I read this could indicate a low freon amount, my unit uses 410a. I borrowed a neighbors gauge, surrounding air temperature is 65 degree, and as I read this I have high suction pressure thus a low freon with likely leak enter image description here do you concur dr.?

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  • the relay is switched by 24 volt coming from thermostat, check that. The compressor will fail to start if the pressure is to high
    – Traveler
    May 14, 2023 at 21:50
  • Uou mean the wires going to the relay with a multimeter? May 14, 2023 at 22:04
  • the really has low voltage (24 V) for the coil, and high voltage (120V) so set your multimeter appropriately.
    – Traveler
    May 14, 2023 at 22:41
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    you were right! thanks! May 15, 2023 at 0:24
  • You need licensure, recovery equipment and upstream supply chain to deal with recovered refrigerant, in order to mess with R410. Of course, some equipment is designed from the ground up for DIY installation that doesn't require refrigerant handling - Pioneer etc. overcharges the outside unit somewhat and fills the rest of the system from that; and MrCool uses special self-sealing quick-connect line sets. May 15, 2023 at 1:32

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Wow, the fins of the condenser are really furry. That debris should be rinsed off so the unit can function better.

Each refrigerant has a definite relationship between temperature and pressure. The blue and red scales on these gauges show PSI; the pink scale is calibrated to temperature. We see that both gauges are showing the same pressure, so we can conclude that the compressor has not been running for some little while and the system has reached a non-running equilibrium. The pink scale reads about 66 °F which matches your reported temperature.

We can't determine whether the refrigerant charge is correct when the unit isn't running.

It sounds like you'll need to do more electrical troubleshooting. Trace the wires and compare with the wiring diagram to confirm that you've re-connected everything correctly after those parts were replaced. Use a volt meter to confirm whether the correct voltage is reaching both the compressor and the fan. Wiggle the connectors and confirm that they're clean and snug. Check all the connections: at the capacitor, input and output of the contactor, input and output of the disconnect, the disconnect itself, the fuses inside the disconnect (if any), the circuit breaker.

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The first thing to check is the low voltage side of the contactor. If the new connection came loose, it could obviously cause the contactor to fail to close.

Assuming that is not the problem, it looks like this unit has a high pressure switch in line with the contactor. This is on the 24V signaling line. You can try briefly jumpering it out by attaching a jumper to both sides. If it is the switch preventing the contactor from closing, then it will close one jumpered out and compressor will start. (Obviously I'm assuming the thermostat is calling for cooling).

Assuming it is indeed the pressure switch causing preventing the contactor from closing, we now need to figure out why. This switch on your model requires 610 PSIG to go open circuit (cutting off the contactor), and should go closed circuit again once the liquid line pressure drops below 410 PSIG. Assuming you connected the gauges correctly, and that image was the system not running, then your pressure is nowhere near high enough for the pressure switch to be cutting off, at least not before the compressor starts.

Especially since the pressure has equalized on high and low sides. (And matches the temperature, suggesting that the refrigerant is not crazy low or anything).

This would suggest a faulty or worn out high pressure switch, which needs to be replaced. Of course this may not be the only issue with the system. For example if the switch was worn out, that would suggest another issue causing high head pressure, which needs to be addressed, lest the new switch get worn out.

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