Hi All I am having problems with a PC400-8(Serial No. 70769) air conditioner. It will work fine for a couple of hours then it just stops blowing cold air this will then be the pattern for the rest of the day. Sometimes shutting the machine down and starting again will get it to work. When it starts to play up it doesnt send any power out to the clutch making me think that it isnt being told to kick the compressor in. I have recharged the system and change the receiver dryer before christmas. There isnt any stored defects in the machine monitor for the air conditioning system. Does anyone know much about climate control system on these machines? The schematic I have doesnt really show any inputs to the controller as to what would be telling it to shut the compressor off. Any help would be much appreciated. Thanks
check the connector of the compressor on the engine compartment side. Is it loose or rusty?
When it plays up I don't get any power out to the compressor making me think the controller is telling it not to cut in. But I can't find what is telling the controller to play up like that.
condensor or evaporator could be plugged up causing high pressure in system and kicking it off
I have tried running a bypass wire on the pressure switch under the cab but it still played up.
Sounds like it is freezing up the evaporator coil. Check and make sure the thermostat probe is inserted properly in the coil. If it is the probe may need to be replaced. that is the normal cause for something like this
I ended up getting the thermostat and all temp sensors that are located in the hvac box inside the cab. The price of the were cheap enough that it wasnt worth it to replace them 1 at a time and have to keep pulling the seat and hvac unit out. If you ever have one apart they have a pretty complicated arrangement of blend doors to direct the air flow and no heater tap to shut off coolant flow through the heater core.