Was the pop sound under the bonnet or in the car?

Could just be the blower motor

it sounded like it came from the left side of the bonnet, like passenger side in between like the dash and engine bay

Check fuses? No smells of burnt electrics? Does the AC Compressor still fire up when you turn the AC on? AC Thermo fan come on?

That's the basics to check. If all thats working it might be something under the dash or something more technical ..

__________________
[SIGPIC][/SIGPIC]
Should have bought an STI

It could have been a failed hose or failure of compressor, in which case would cause large amounts of gas to leak and cause poor a/c performance.

update guys, when I turn my aircon at first everything runs smoothly and normally as if there is no problem at all...... I drive say 5-10 minutes then I'll notice it stops blowing any cold air out.... I put my hand over the vent and I can still feel slight air flow.... but its like after a while it gets blocked off by something

I turn the dam thing off and leave it for about 5 minutes, turn it back on and its working normally again... but then the same thing repeats itself after 10 or so minutes it just dies again

Any ideas anyone ?

Sounds as though your evaporator coil is freezing up, but it would usually take longer than 10 minutes. Maybe i'm just used to truck ac systems.

This is due to the thermostat or thermistor not cycling the AC comp off and allowing time for the coil to drain off condensate.

I haven't changed a thermostat on an impreza before, but i think it could be a bit of work, as the gas would have to be reclaimed from the system to allow removal of the evaporator box unit to access the thermostat.

Cheers
Matt