How do you check the high and low pressure of the A/C and what should these pressures be?

Thanks

 

there are ports on the lines of the ac that you can hook-up to with gauges.
have not looked at them in years, but they are sold in parts stores.
i still have a recharge accessories kit from IG-LO Products of Hernando, Ms that i probably bought 15 years ago.

the pressure is dependent on the outside (ambient) temperature. for example: at 90 degrees the low side should be 26 - 35 psi and the high side should be 205 - 245. the kit and the readings here are for the old r-12 systems. No idea if those figures are the same for the R-134A systems.

Just make sure that you do not try to add freon to the high side. only put it in the low (suction) side.

 

The pressure should be drastically different on the high and low sides. It really doesn't matter if ur using R-12 or R-134a it should still be different. With R-134a the temp and the pressure are really similar. SO if the guage reads 30 PSI then the low side is approximatly 30 degrees F. The high should be around 200 and the low should be around 30-40. 26 is pretty damn low, i think the lines will freeze when the refrigerant gets that cold.

 

i think you may have misread it; i took the info from the product instructions of the IG-LO product.
i figured that 134a was the same - just wasn't for sure - thanxs for that.

but in the post:
temperature (outside) ---------- 90 degrees F
low side -------------------- 26 psi to 35 psi
high side ------------------- 205 psi to 245 psi

like these forums - they do not allow blank spaces (well, i guess between words, though)