High pressure on the low side

[rbaggett]

I have an a.c. system that registers 32 on the low side and the manual says it should register between 22 and 50psi. But it only stays at that reading for a few minutes and then goes up to 110 psi on the low side. Could this be a pressure sensor problem or maybe a stopped up expansion valve. The pressure on the high side shows to be normal even when the low side pressure goes up.