Hey All I have a 1990 Toyota Dyna YH81R dual cab "truck" and I'm having some issues with the air conditioning. The system has been without gas charge for some time (years?) and the condensor had been removed for around 6 months (to adjust steering box) I have installed a new receiver dryer, new O rings on everything I've touched, new schrader valves, fitted a high/low pressure switch, cleaned everything up (also rebuilt the engine and a few other things...) the system has been evacuated, ROC oil added, and hychill a/c gas charge added. The switch in the dashboard (a variable resistor type thing) had failed maybe 5 years ago, and has been replaced with an on/off toggle switch, the a/c system did work with this before it lost its gas charge. The a/c system will not switch on, the compressor clutch has no power going to it, the condensor fan does not turn on either. There is power on both sides of the a/c fuse, but no power at the toggle switch. If the compressor is jumped with 12v, and obviously the condensor is cooled (using running cold water) then the system works, the pressures are good on the gauges, and the cooling temp is down to 6 degrees in the centre vents (on a 33 degree ambient temperature day) and we are all quite happy.... My guess is that there *may* be a low pressure switch somewhere in the system (from the factory) that I have not found yet, and it is probably jammed, thus cutting power to the system. Anybody out there with a wiring diagram or previous experience in the matter? I'm really keen on getting this going over the christmas long weekend! Robert.
