A/C problem

I have a 2001 chrysler voyager 3.3L…I have changed my evaporator and also i just recently changed my a/c blower…The problem I have is I drive for about 30 to 40 mins. and the pressure of my a/c descreases even if i put it on full power… Than i turn it off, driving for like 20 mins. to 30 mins. I turn it back on and the a/c works again, but I have to do the same steps when i take long road trips thru out the whole trip. what might be the problem. thank you

When you say pressure, do you mean the amount of air coming out of the system or do you mean the pressure inside the system. If so how are you measuring it?

It sounds to me like it is frosting up and that is reducing the air flow. It may indicate it is incorrectly charged and may need the charge increased or decreased. If you have a cabin filter on that Voyager, then it may need to be replaced.

I’ll second Mr. Meehan’s advice.

Not sure about this vehicle, but when you changed the blower you might have displaced the temperature sensor that is supposed to be attached to the evaporator (close to the fan). This could cause the evaporator to ice over and not cycle as it should.