My furnace fan and AC compressor turn on when I first put the thermostat on cool. Once the house reaches temperature both units shut off. When the house warms up again only the furnace fan turns on and the compressor unit does not come on. If everything is shut off and there is a long period of waiting (several hours) the compressor will come again. I have examined the wires to the compressor unit and when the points to the compressor relay are pushed with a screwdriver it immediately comes on. I also found several loose wires in the furnace that are attached to the low voltage transformers. I replace the wire nut that was too small but the same problem continues. Is this a low voltage problem or can it be a problem with the thermostat? The transformer seems to be a little warm as well but I don’t know if this is a normal operation.

Thanks