Low volume of air from vents 93 bonnie
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Posts like a V-Tak
Joined: Apr 2008
Posts: 26
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From: Connecticut

I have a 93 bonnie with 118000 miles. The volume of air coming out of the air vents is very low. The fan speeds work fine - I can hear the fan labor at high speed trying to push out air. The floor, dash, and defrost settings work fine. I think the fan sits in front of either the heater core or the A/C condenser - I'm guessing which ever one it is - its fins are clogged and not allowing air to flow thru - does this sound plausible? Do you guys know if the heater core or the condenser is immediately in front of the fan? Or do you think another issue exists? - such as a duct door not opening fully somewhere close to the fan?
Any thoughts?
Thanks.....
Any thoughts?
Thanks.....
You likely have lost vacuum to your HVAC, which controls the door for that. Check all the vacuum lines coming of the vacuum tree on the engine.
Pay particular attention to one that runs to the firewall, slightly to the driver side of center.
If those are all okay, pull off the cover under the dash on passenger side and check the lines,

But it is most likely under the hood at that line (he said hopefully)
Pay particular attention to one that runs to the firewall, slightly to the driver side of center.
If those are all okay, pull off the cover under the dash on passenger side and check the lines,

But it is most likely under the hood at that line (he said hopefully)
Thread Starter
Junior Member
Posts like a V-Tak
Joined: Apr 2008
Posts: 26
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From: Connecticut

I have checked the vacuum lines under the hood - all are good. I will also check lines under the passenger side dash - thanks
I'll let you know what I find.
I'll let you know what I find.
Okay. Turn on the AC and check to see if the cold air is coming out of the defroster instead.
Or, if it is coming out of the floor duct instead. There is a different valve/door depending on the symptom.
Or, if it is coming out of the floor duct instead. There is a different valve/door depending on the symptom.
You could also try this out --- Evap Cleaning 101 (climate control)
Not sure if that might be the problem, but I am sure it wouldn't hurt
Not sure if that might be the problem, but I am sure it wouldn't hurt
Senior Member
Certified GM nut
Joined: Jul 2004
Posts: 1,606
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From: West Point, Utah - Village Idiot

(both of them)I had to do it at least twice on my '93. A typical symptom on that car was reduced airflow from the passenger dash vents compared to the driver'*. When my wife whined about being too hot over there, I knew it was time to clean the evaporator.
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