check the oil sounds like it has none
There is a fuse, relay and switch on the low pressure side that will inhib compressor from turning on if there is not enough pressure.
Most likely the problem is with the Pressure Sensor in the engine block.
High oil pressure is not usually a problem. The relief will open around 100psi on most engines.
The diesel combustion pressure depends on various factors. The model and the type of diesel engine is important.
18.6 ATM for diesel UDER ATMOSPHERIC PRESSURE AND TEMPERATURE.
Overheating and high boost pressure typically are signs of an EGR problem.
where is the oil pressure switch on a 2004 Volkswagen t5 diesel
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diesel doesn't burn. it combusts under pressure
The auto combustion pressure for a diesel engine is 580 psi. This is compared to the 200 psi of the gas powered engine.
The problem is a leak inside the high pressure oil system. When it is hot the leak expands and causes the truck to not start.
One of the ways of starting a diesel engine is turning the key to stat position without turning the engine on. The second step is to wait for the glow plugs to heat up.