Common questions

What is an oil pressure safety switch?

What is an oil pressure safety switch?

The oil pressure differential switch breaks the control circuit and shuts down the compressor when the pressure difference between the oil pump outlet and the crankcase is too low. NOTE: Oil pressure safety control with an approved switch is a condition of warranty !

How does a fuel pump work when there is no oil?

One wire goes to the pump, one to the start circuit, and the other to the ignition circuit. So, when there is no oil pressure, the switch connects START to PUMP, and as soon as you start cranking it runs the pump. When the oil pressure comes up, the switch connects IGN to PUMP, for normal running.

What does the low pressure switch on a Chevy do?

The low-pressure switch is designed to shut the compressor down if the pressure becomes to low or the evaporator freezes. The oil for the compressor is suspended in the Freon, and if a leak in the system occurs, the oil, being heavier than the Freon, will be the first thing to leak out.

What happens when you hit the starter on an electric fuel pump?

The switch will also let the pump run when you hit the starter because the engine doesn’t have oil pressure yet. One wire goes to the pump, one to the start circuit, and the other to the ignition circuit. So, when there is no oil pressure, the switch connects START to PUMP, and as soon as you start cranking it runs the pump.

What should the fuel pump pressure be to start the engine?

The fuel pump produces much more than just 50 PSI of course but the bare minimum the engine needs to start is 50 PSI. Anything less and it will crank for ever before it starts or not start at all. So, the very first thing you need to do is to verify that the fuel pump is delivering at least 50 PSI of fuel pressure while the engine is cranking.

One wire goes to the pump, one to the start circuit, and the other to the ignition circuit. So, when there is no oil pressure, the switch connects START to PUMP, and as soon as you start cranking it runs the pump. When the oil pressure comes up, the switch connects IGN to PUMP, for normal running.

The low-pressure switch is designed to shut the compressor down if the pressure becomes to low or the evaporator freezes. The oil for the compressor is suspended in the Freon, and if a leak in the system occurs, the oil, being heavier than the Freon, will be the first thing to leak out.

The switch will also let the pump run when you hit the starter because the engine doesn’t have oil pressure yet. One wire goes to the pump, one to the start circuit, and the other to the ignition circuit. So, when there is no oil pressure, the switch connects START to PUMP, and as soon as you start cranking it runs the pump.

The fuel pump produces much more than just 50 PSI of course but the bare minimum the engine needs to start is 50 PSI. Anything less and it will crank for ever before it starts or not start at all. So, the very first thing you need to do is to verify that the fuel pump is delivering at least 50 PSI of fuel pressure while the engine is cranking.

Author Image
Ruth Doyle