AC Pressure Sensor Readings

[Tater55tot]

I am trying to see what my AC pressure readings are after installing ac. The only option for the pressure sensor (3 wire sensor, not switch) is in Volts or Millivolts.

Is there a way I can see PSI, or what formula can I use to convert V to PSI? I know the computer sees PSI because that is what my electric fans run off of. I

My OS is off an 04 Chevy 5.3 V8.

[TheMechanic]

0.1 volts (1 psi) and 4.90 volts (425 psi)
B=y−MX
Here is a typical example where a pressure sensor is used to measure 1-429 PSI and the output is 0.1-4.9Vdc.

First, using the Y=MX+B formula, we determine what each value is in order to calculate for Y.

X = 4.8 (since 0.1-4.9V has a span of 4.8 volts. If it was a 0-10Vdc output, X would be 10)

M = 88.3 (use divide the Units by the Voltage or Current - 1-429/0.1-4.9 = 88.3) which results in PSI/Volts

B = -8.83 ( since the output starts at 0.1 volt, there is an offset. We calculated a value of 88.3 PSI/Volt, therefore, 0.1V = -88.3) If the output of the sensor was 0-5Vdc, then there would be no offset.

To test that the values are correct, put them in the equation. 4.9 volts out should give us 429 PSI and 1 volt out should give us 88.3 PSI.

Y=88.3(4.8) + (-88.3) = 429PSI Y=88.3(0.1) + (-88.3) = 1 PSI

We are off ever so slightly by about 3 PSI. That is just due to a rounding factor

[TheMechanic]

Excel chart for ya.
volts to psi table.xlsx

[Tater55tot]

This is what I needed, thank you. I will double check with my gauges, but seems like my sensor is reading correct.

Reason I was curious was because when I was charging the system, I didn?t have my E fans calibrated properly and my head pressure got up to 350psi and the compressor didn?t cycle off. It has also not cycled off at all since installing the ac, but pressures seem normal (high side: 200-210 low side: 50-70) ambient temp = 90-95.