A/C, what should the low and high numbers be on this car when warm?

Good evening,

The high side should be 2 times ambient temperature or out air and the low side should be 25-30 pounds rock solid.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Roy

I see. Why is it that some cars are normal or should be at 45?
Also, why does a weak compressor cause the low side to go high?

45 is too high. It should be 25 to 30.

No, a weak compressor will not build pressure.

The 90 on both indicates a possible compressor. If the compressor is engaged then it needs a compressor.

https://www.2carpros.com/articles/replace-air-conditioner-compressor

I attached the procedure for the compressor replacement.

I also attached the wiring diagram for the compressor in case it does not engage.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Roy

Yes, it does engage. But am trying to understand the logic behind it. If it's at 90 on low side means not building pressure, but the pressure is high so how is that?

When the system is not working, the pressures are called static. Those pressures should be equal on both the high and low sides and within 5 degrees of outside temperature.

Roy