AC air flow problem

[gold10go4]

The AC unit on my 2001 S-10 works well for the first hour to hour and a half driving. Then the air from the vents decreases and it's as though the AC isn't functioning at maximum. The air is still cool, but there is less of it. After it sits for a while, it's fine and operates normally. Is this an evaporator freezing up? That happened on my house a couple of times. Same thing happening on my S-10? It also happens on my wife's car, '01 Regal. What's the solution? We live in Florida and we're not running the AC unless it's very warm.

[MT-2500]

Is the evaporator draining good.
When you stop with engine running and air on does it come back to cold in 2-5 minutes?
Does the drain have a elbo pipe or fliper on it.
In some cases the drain pipe will catch road air and keep it from draing on the road.
If that is the case run a hose straight down 4-6 in,
MT

[gold10go4]

I haven't as yet looked at the drain to see if it's clogged. I do notice that after the truck is stopped in one spot, there's a lot of water below the truck from the AC unit. I'm assuming this means it's draining properly, but not 100% sure. I don't think the air has ever been low in temperature. It's just that when the problem arises, the cool air that's there is diminished - there is just simply a reduced air flow of what available cool air is there. When I restart the truck after a half hour or so, the air flow seems to return to normal.

[MT-2500]

Not sure it is your problem but.
It is not a stopped drain that does it but air flow on the road blows against the drain and keeps it from draining on the road.
If it drains a lot when you stop.
Try putting a defector over drain or putting a longer drain hose on it.
If that does not help put a set of AC gauges on it and give us your low and high readings at idle and at 2K rpm.