I have an older 2 1/2 ton York heatpump-- installed in 1989. No manuals, and all info on unit itself has been erased by weathering. Intermitantly the red EM light comes on flashing 4 times, pause, then 4 more times, etc. When that happens the outside fan stops turning and no cool air. I turn unit off at the thermostat, wait 5 minutes, turn back on and unit runs fine. This happens, as I said, intermitantly, usually with about 6 to 12 hours between stopages. Other than finding out what's wrong, I would also like to find some reference to de-code the number of flashing red lights on the thermostat -- what does 2 flashes mean? What does 3 flashes mean? Etc. Especially want to know what 4 flashes mean! Any help will be greatly appreciated!