I have a rheem rpka 030jaz units beenworking fine... started to notice it was not cooling...
Checked outside unit and it wasn't running... I had this probem about two years ago
Replaced contactor and that fixed problem... so I checked the new one removed cover in points and if I manually press down on conact unit will fire up... so I checked to make sure I was getting the 24v at the contactor it's only reads about 17 -18 v from yellow wire to ground (chassie)... thought maybe thermostat was bad replaced that and still the same just 17v... can anyone lend a helping hand?

Go to both 24 volt terminals on the contactor and see what your reading is. If less that 24 volts or so you have a weak transformer or other low voltage problem. You will need to trace the problem starting at the transformer to see where the voltage drops off. If there are low voltage components in the outside unit like high or low pressure controls they can also cause a low volt problem.

OK it's low v there on both yellow wires... I trace them back to a little browm sq box both yellow wire come out of this box plus a brn on going to the other side of contactor... there's also a larger brn wire that has 24v going into this box... possible this is the relay you speak of... so if 24v going in and only 17v at yellow wie















Go to both 24 volt terminals on the contactor and see what your reading is. If less that 24 volts or so you have a weak transformer or other low voltage problem. You will need to trace the problem starting at the transformer to see where the voltage drops off. If there are low voltage components in the outside unit like high or low pressure controls they can also cause a low volt problem.

((possible this is the relay you speak of))

Relay? I did not mention a relay in my reply to you I mentioned a contactor.

((I trace them back to a little browm sq box))

I have no idea what this box is or what it does by your description. Is it located inside or outside? Does it have a brand name or part number?

As I mentioned before you need to trace the problem down to where the voltage is less than 24 volts. This will be the general area where the problem will be located. You might post pictures so there is no misunderstanding the nomenclature of the HVAC descriptions of the part or parts you are talking about.