My 97 3500b's air conditioner coil seems to be freezing. When I start out I get lots of cold air with a good airflow from the vents. over the course of a couple of hours, I get very little airflow and only slightly cool air. The pressure in the system according to a gauge on a refill canister is where it should be so I did not add any.
I think the rad inside of the heater compartment is getting clogged with ice. If I run the vent for a while and then switch back to AC I will get some more air but the whole cycle starts over. How can I fix this?
Thanks

 

The condensate drain tube/hole is likely clogged and allowing water to build up and freeze. Clear the clog and the issue should go away.

 

Tube is clear
Could it be the freeze sensor? How would I check?

 

Does it have one??

 

No idea the Haynes I have says on later models there is on I don't know when later models start.

 

Can you get access to the evaporator core, without having to disassemble the entire van? Might be worth taking a peek, and cleaning out any debris the inevitably collects there....

 

I just checked there are wires going into the cowling where one should be how would I check to see if working? and where would I find a part number?

 

I found the part number can I change it without draining the AC fluid?

 

Not seeing that sensor on the wiring diagrams.

When is the last time you had the a/c system serviced? Freezing up appears to be a symptom of being low on refrigerant.

 

I will have a shop look at it I have a gauge that comes with the refill can it showed in the green so I didn't put any in.
I have no idea what the previous owner or her mechanic did so I think a professional is in order.