Car A/C blows cold air till I reach 45+ mph?

I have a 2004 honda civic and my AC is pretty good. Like it blows cold air but once I hit about 45 mph the AC will actually turn from cold and get kinda hot and humid. It's weird. Then like once I return to about 40 mph it'll get cold again. Any suggestions? Perhaps include average cost to fix it?

It sounds like it needs a recharge. You can get one of those quick-shot things. Don't put too much in. Get someone who knows these things to help you.

If you think your car air conditioning is not blowing cold enough the first step is to check the output temperature at the center duct with a thermometer. The resistor controls the flow of electricity to the motor, w/ the 4 setting not limiting the current at all, which is why you the fan works at that speed.

You very likely have an airflow problem, because the fact that the system cools on the road is an indication that it is able to pick up heat, but it's not able to get rid of it at slower speeds.