1994 Pontiac Sunbird Amount of air from vents

Tiny
PROFESSORCHAOS96
  • MEMBER
  • 1994 PONTIAC SUNBIRD
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 280,000 MILES
The amount of vents coming from the vents in my car seems to be inadequate. When on the vent setting, the middle vent has plenty of air, however the two on the passenger side and the one on the drivers side is about 1/4 of that in terms of flow. The defrost vents don't seem to be putting out alot, either. The amount of heat is fine, and it transitions from hot to cold just fine as well. Another thing to note is when I set it from hot to cold, flow increases quite a bit. Are these cars known for blockages? Or is it the blower motor or actuator? OR, is this normal for these cars? Any help would be appreciated, thanks!
Wednesday, December 16th, 2009 AT 4:28 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
It isn't normal. Actually, if it works normal on AC but not heat, my guess is the heater / ac vacuum actuator isn't working or there is a vacuum leak causing the system to not function properly.

Here are schematics of both the vacuum system and the HVAC system. Check for proper vacuum the both actuators (vacuum schematic) and make sure the mode valve shaft is working (HVAC schematic).


https://www.2carpros.com/forum/automotive_pictures/249084_vent_1.jpg




https://www.2carpros.com/forum/automotive_pictures/249084_actuator_2.jpg



You will most likely need to enlarge the pictures.
Let me know what you find and thanks for using 2carpros.com.

Joe
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Saturday, December 19th, 2009 AT 12:10 AM
Tiny
PROFESSORCHAOS96
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Appreciate the response Joe. The pictures won't enlarge, and if I stretch them I can't pick it out. Is there any way to send over a link, or perhaps email them to me? It's professorchaos96@hotmail. Com Thanks for the help!
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Saturday, December 19th, 2009 AT 11:40 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
I was afraid of that. I will try to send it to your email. Keep your fingers crossed.

Joe
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Saturday, December 19th, 2009 AT 5:19 PM
Tiny
PROFESSORCHAOS96
  • MEMBER
  • 21 POSTS
It worked, thanks for the photos Joe; one question though, where are the exact location of the actuators? Are they just on the back of the in dash unit? Because what I gathered from your first post is, airflow should be the same whether it's on the hot or cold setting. I'm thinking the heat/defrost or the A/C-heat actuator may be bad. Or, is there any chance there would be any leaves or something in front of the heater core? Because the air has to flow through it before it gets to the interior. Thank you again Joe, appreciated the responses.
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Saturday, December 19th, 2009 AT 8:38 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
I'm gd to help, and really glad you got my email. I can never get it to work, but my 12 year old son had to show me how to use it. With all the computers in cars anymore, and nearly 30 years of working on them, one would think I would have no trouble, but.

Yes, they are on the inside. If there was a blockage of leaves, I think you would smell something from it but that isn't impossible. The first one I would check is the heater / defroster. It could limit the air flow.

Let me know what you find, and thanks for using 2carpros. Com.

Joe
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Sunday, December 20th, 2009 AT 11:54 PM
Tiny
PROFESSORCHAOS96
  • MEMBER
  • 21 POSTS
I was having some radiator troubles, so I replaced mine with a new aluminum core rad last night, as well as some better coolant (and a complete flush, of course) and the air temperature at the vents now is awesome, you can barely hold your hand to it. I'm surprised the radiator made that much of a difference. I'm going to get my hands on an actuator when I get the time and hopefully get a bit more airflow. Thanks for your time Joe, Merry Christmas!
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Tuesday, December 22nd, 2009 AT 7:03 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
I'm glad it's fixed! Thanks for the positive feedback. It may sound crazy, but it makes me feel good to have helped someone.

Thanks for using 2carpros. Com, and I wish you and your family a great Christmas!

Joe
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Tuesday, December 22nd, 2009 AT 8:11 PM

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