For sometime the AC seemed to make unusual sound, like it comes on for too short of a time and not sounding its usual self but more of a hum, so was keeping an eye on the thermostat temperature inside the house to see if the AC keeps up with the set temperature.

Today noticed that the set temperature is 76 but the downstairs temperature is 80. This does not happen normally, always the inside temperature is equal to the set temperature so there is something wrong.

Went outside to take a look, there are two AC units one for upstairs and one which is newer for downstairs. The older AC for upstairs was coming on and sounding normal with its condenser fan working, touching the lines from it, the smaller one was warm but not hot and the larger line was cool but not cold. The newer one which is likely the one with a problem was coming on and then shutting maybe 30 seconds later, the smaller line coming from it was very hot and the larger line coming from it was very cold but not iced up, its condenser fan did not come on while it was being observed even when the compressor kick in a few times.

Have not checked line pressures, the gauge set that I have is for R134 not sure if it will work with this house AC but I can try to see if it can measure the pressures.

Sometime ago the upstairs AC that seem to be working well now had to have its capacitor replaced. Could this new problem with the downstairs AC be also capacitor related?

Please chime in with your suggestions and comments. A few photos of the downstairs AC unit is attached for identification and to show condition of the unit and its components.

Did a simple test of waiting for the compressor to kick in and then giving the fan a push and the fan came on and stayed on, indicating the fan capacitor is the most likely culprit. Capacitor is rated 35Uf 5Uf 370VAC 50/60Hz. Had purchased one similar to this for the older unit a while ago from Grainger: https://www.grainger.com/product/DAYTON-Round-Motor-Dual-Run-Capacitor-2MEJ5?cm_sp=Home--Purchased_Products--HPMPPZ&cm_vc=HPMPPZ

So probably need to pick up another one.

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