When our compressor kicks on, the compressor will run and shut off or not come on at all. When running the discharge air is 64 degrees and the return air is 78 degrees. I have only a couple of answers, bad relay? Low head pressure? Or capacitor??

What kind of unit are we talking about.

What kind of unit are we talking about.

We have a trane 4 ton heat pump with aprilaire 8344 non-programable thermostat. Unit runs great when the compressor comes on...

Sounds like it is low on freon and the low pressure switch keeps kicking out.

sounds like it is low on freon and the low pressure switch keeps kicking out.

I would agree, but the unit ran all yesterday afternoon and last night and this morning and went to check this after noon and same thing. Turned unit off and waited for about 5 minutes and then turn unit back on and it is working fine. If it was low on freon, the freon line would be warm and no condensate on lines, also the discharge temp is what it should be around 64 degrees. Have plenty of condensate in return line so I'm at a loss here. Its around 100 here so it would help to discover answer...

Is this a heatpump? Or just a ac unit. Next time it goes off. Look outside in the electric panel and see if the contactor is still pulled in. If not sounds like a t-stat problem.