I know it's not time for AC yet but I've been think about it. What is the proper pressure for our trucks? It says 2lbs under the hood. But that has me confused. So what's the proper high and low pressure?

 

I have done a/c work for years. Believe me when I say it worth the money to pay a pro. If you do it yourself, you have probably never experienced to full effect of your a/c system. It needs recovered, vacuumed, oiled, then recharged with clean and pure refrigerant.
The pressures should be around 100 psi and the charge is 2lbs, 1oz.

 

I'm just wanting to check the pressures not add anything.

 

Anybody else?

 

After a system has sat and lost some charge the pressures are going to be off because air has seeped into the system. Like said above the right way is the only way. If it's not cold enough for you buy a DYI kit and add a little, but not knowing true pressure due to air in the system you could possibly make it worse. The good thing about vacuuming out the system is you can check for leaks, you get all the moisture out of the system and your reading will be much morer accurate.

 

The only way air gets into a closed and pressurized system is if you open the system up after sitting or not over a period of time even the OEM states a certain amount can seep out and be normal. But air is NOT getting in.

You CAN force air in if you don't bleed it out of the manifold gauges and hoses when adding freon.

 

Depends on ambient temperature, lets say it's 85F outside with the engine running and gauges attached you will likely see around 40psi on the low side give or take 10psi and high side gauge should read around 250psi give or take 20 psi. Higher ambient temps will make those pressures higher on both sides.

 

The seals in the system rely on refrigerant oil to stay lubricated (swelled) so with the system not running during winter months they will contract and allow air to seep in, if the system were perfect nobody would sell the DIY kits.

 

Those readings can be off if there is air in the system giving you a false feeling that everything is within spec's. The only way you will get accurate reading is to evac the system of all freon and air.

 

Ok let me begin by stating I am factory and ase certified in automotive air conditioning.

Seals will seep OUT not in, the entire system is pressurized and when sitting both high and low sides will equalize to an even pressure thruout the entire system so unless barometric pressure is higher than the system it is impossible for any air to get into the system.

The amount of barometric pressure required to over come the pressure inside the system would make this planet uninhabitable.