2000 Civic. I bought the car used and the AC has never worked. Followed the directions on the can, ran air on high, hooked up the recharge can to the "L" AC line, squeezed the trigger... car started to run real bad then blew something OUT the K&N filter. Was it somehow sucking freon through the intake? I stopped and car still runs OK but of course AC still does not work.

 

I don't see how that's even possible.

 

Just because the A/C fails to blow cold, doesn't necessarily mean the system is low on refrigerant. Start the troubleshooting by determining whether the condenser fan runs and the compressor clutch engages.

 

I'm not sure what blew out of your intake, but you need to be more careful with a/c systems. If there is any air or moisture in the system it will not work well.

If the engine started to run bad it could be that the compressor was loading down the engine. It could be that it was seizing or perhaps just created high pressures due to an obstruction or an overcharge.

I would look to see if perhaps the "pop" wasn't out of the intake, but a refrigerant line somewhere near there.
Good luck

 

Excellent point