No ice or dirt on coil, blower runs, good suction at return air register, filter is clean. No condensate in the afternoon, good condensate in the morning. Outside temp 75F at night and 105 in the afternoon. No changes to home no rooms added, unit is 8 years old and has been working well. 3.5 ton unit in 1800 sq foot home. Morning pressures are 95 low side and 175 high side. Afternoon pressures are 115 low side and 250 high side. Using R22 guages No hissing sound at compressor however it is making rattling sounds like rocks in a coffee can. Two hot lines and two cold lines at reversing valve. Cycled from cool to heat and back once (wife almost killed me and afraid to do it again) want to try hooking my gauges from the low side to the true suction but do not know where the true suction is. low side pressure is off the temperature charts which end at about 86psi. Have not checked amp draw however unit is not tripping breaker. leaning toward air in system, worn out compressor or leaking/stuck switching valve. THANKS FOR ALL THE REPLYS SO FAR, THEY HELPED ME KNOW WHAT QUESTIONS TO ASK!