I have a product that we perform submersion testing on to determine susceptibility to water intrusion. The product is heated to 120C and then placed in an ice bath. I have measured the pressure / vacuum during testing and have determined that the pressure can rise to 5 psi while heating and drop to -10 psi while submerged. The ideal gas law aligns with the 5 psi while at 120C but when dunked, the calculations state that the pressure should be around -2 psi. I am trying to determine how to calculate this result. Any advice?