This unit is running but not pushing out cold air. When it was turned on for the first time the air was cool , but gradually stopped cool and is only pushing out hot. The unit seems to start up OK, (pulling air in), but the compressor doesn't seem to kick on. Where would the high pressure switch be to reset it to operate on cool- ? { lennox high-efficiency heating and cooling unit : CHP20V: 12:00 to 12.60 seer }

The pressure switch will be in the same area as the compressor, it will have a red button on it. BE SURE to shut the power off before entering the unit, also you may want to check your filters while you are up there. I would say if you find the pressure switch tripped then you need to find out why? Is the condenser fan running? Is the condenser coil clean?

So I found the switch which was tripped after correcting it the unit is pumping out cool air. While looking at or around the compressor the switch was located on one of two green parts; around the second part {that was green} there seemed to be some kind of brown oil residue is this normal? And what should be done about it?

The oil you are seeing may be a sign of a leak in the system, for this you may need to contact a pro. For they will know what to look for and how to repair this will also involve recovering the system and for that you MUST be EPA certified. If you are lucky this may just be oil from an old leak that has already been repaired, look around, can you see where the oil is coming from?

Yes, I do believe it is from an old leak. At least the other side was nice and clean with new wires and all that stuff. " If its still working dont fix it." That's what I say, but yes consult an pro first... thanks again!