Vehicle=Toyota T100 (fullsize) pickup extended cab SR5 package 1997 model. ABout 170K miles in Alabama weather. No other problems. Factory air installed. My AC was starting to cool less efficiently. Checked charge which indicated low charge and recharged as needed with R134 w/oil. Pressure is good on both sides. The temperature differential between the high and low sides seems good. Very cold on the low side. Overall problem seemed to get better for 2 weeks but maybe that was my imagination. Now worse. When AC button is on there is an audible, rhythmic clicking in the cab and in the engine compartment. The engine clicking actually causes the truck to lurch when sitting still with foot off brake. The engine compartment clicking is the clutch on the compressor kicking in over and over again without staying on. The cabin clicking is in the cooling unit. The clicking goes away as does all of the AC function when I disconnect the harness from the amplifier (not an audio amplifier but the amplifier in the cooling/evaporation unit). I have not discharged the coolant yet. Before I have it done, can anyone help me diagnose what component of the cooling unit this is likely to be? Some suggested it might be a CCOT switch? What is this and where can it be found? Could the cause be a Thermistor, pressure switch, expansion valve, etc? I can give additional details if it would help. I have the Haynes repair manual for my truck with general AC stuff but not the AC-specific manual version with micro-details. Many Thanks! Matt
- posted
19 years ago