A/C Fan Blower Question?
Thread Starter
Instructor
Joined: Mar 2008
Posts: 221
Likes: 0
From: Farifax Station VA
A/C Fan Blower Question?
The A/C fan sounds strong and sounds like it is moving good air, but very little comes out of the vents. So a few months ago I had the dash out and all of the A/C ducting removed...I cleaned it all out, fixed a few vac lines and put everything back together. Still the fan doesn't move any air. Could there be a valve or something that is diverting the air outside the car? thanks
Melting Slicks
Joined: Mar 2009
Posts: 3,126
Likes: 15
Is it poss. that the blower motor is running backwards? Since we are dealing with DC current if the polarity of the wiring going to motor has been switched, it will run backwards but not move much air. Is air blowing out heater ducts under dash or defrost vents on top of dash? Let us know about those things and repost results. mds...
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
It's common for it to come out the heater vents at bottom instead- check that.
I wrote this up awhile back for that.
On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine is damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood probably also needs replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
I wrote this up awhile back for that.
On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine is damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood probably also needs replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
Thread Starter
Instructor
Joined: Mar 2008
Posts: 221
Likes: 0
From: Farifax Station VA
Yes, some air does come out the lower ducts...but very, very little. and very very little out of the upper ducts. I am still wandering how the air is routed from the fan. when I had the ducting out, I could only see the area where the valve diverts heat.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
The air does not get routed OUT at all. Also if the fan were running backwards it woule be pulling air IN thru the dash vents.
There is a flapper on the pass side of the wiper tray, look in there (might have to remove the screen) with the car running move the selector and see if the flapper closes. Thet puts you on recirculate, flapper open its outside air.
Does the air direction change at all when you move the selector?
Gainy is correct in his post. Don't know how much you took apart, but when I took mine apart, there was a 1" gap between the main duct behind the center dash and the dash vent. Also the duct seals rot and crumple away. Part of my fix was replace all the duct seals, make a seal to connect the center dash duct, rebuild the passenger side vent door, add in a C4 blower and spacer and rebuild the selector switch.
There is a flapper on the pass side of the wiper tray, look in there (might have to remove the screen) with the car running move the selector and see if the flapper closes. Thet puts you on recirculate, flapper open its outside air.
Does the air direction change at all when you move the selector?
Gainy is correct in his post. Don't know how much you took apart, but when I took mine apart, there was a 1" gap between the main duct behind the center dash and the dash vent. Also the duct seals rot and crumple away. Part of my fix was replace all the duct seals, make a seal to connect the center dash duct, rebuild the passenger side vent door, add in a C4 blower and spacer and rebuild the selector switch.
