fan speed decreasing after long drives

[swiftsoles]

Anybody had this problem? The fan stops blowing hard after I've been driving my wrx (2002) for about 2 hours in a row. Even when I crank the thing up to 4, it feels like it's blowing on 1. The A/C still seems to be working, b/c the air that is blowing seems cold.

The funny thing is when I turn it up, the fan noise gets louder as if it should be blowing harder and faster, but I can hardly feel the air coming out of the vents.

If I let the car sit for a couple of hours, everything goes back to normal, and the air will really crank when I turn the speed up to 3 or 4..

Any ideas?

[Hot_Dog]

Have you messed with that black hose that comes out of the firewall near the downpipe? The a/c evaporator could be filling up with water. Does it do it with the heater as well?

[swiftsoles]

You might be on to something. I'm not the original owner of the car, but I know the previous owner had upgraded the stereo. Is this something they could have messed with if they had been up under the dash to install the stereo?

[Hot_Dog]

It could be. Check that hose and make sure its not blocked. If you're looking under the dash, it would come from the center and go through the firewall near the passenger's feet. Maybe someone ran some wire and screwed it up.

[bluedream]

i just had this problem yesterday for the first time although it cleared up after stopping and restarting the car......... my theory was leaves etc over the air intake vent by the windshield but a clogged pipe is just as plausible ...bluedream

[03WRXMA]

Also set the vent to 'recirculate' the air in the car, this helps make it feel 'cooler'.

[Retro]

I have this problem too. I think there is something off with the switch that tells it to blow cold. It always fixes itself after I restart the car, so it cannot be something freezing up, and there are no leaves clogging anything up. It's happened to me 3 times now, but fairly far appart so I'm not too worried.

[chevyeater]

Hmm... I just got this for the first time tonight on the way home. I had the blower on speed 2 for about an hour and ten minutes. After I stopped for gas and got back in I came to the realization there was almost no air coming out the vents. I tried switching from fresh air to recirc mode thinking something was blocking the fresh air inlet, no luck. Changed modes from bi-level to all the others and still no airflow. Got home, shut it off, and crawled under the dash to check all the air doors, all looked fine and were moving freely. Restarted the blower motor and pulled off the hose that cools the motor to see if any air was coming out there and there was, full force. Within thirty seconds of pulling that hose off the blower the airflow out the vents returned completly to normal.

WTF is going on here? My car is STONE stock and never been messed with by anyone.