Weak/Warm Air Flow from Vents?

Tiny
JUANEMMANUEL
  • MEMBER
  • 1998 BUICK RIVIERA
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 179,000 MILES
I recently replaced my entire A/C system: compressor, condenser, dryer, orifice tube, and charged with proper amount of r134 refrigerant. For a time it was cooling better but now not so much. I checked the system with a manifold gauge and got 45 on the low side and 225 on the high side while the temperature was around 88 F. After about 10 minutes of running it, I felt the low side pipe and it was freezing cold and a lot of water had condensed under the car.
Next I removed the AC blower from its place, and looked at it as I turned on the AC at different speeds. Speed changes accordingly, and at high speed it spins very fast as it should. My car doesn't come with a cabin air filter so I know it's not that. What else could be causing a weak and barely fresh air flow from the vents?
Tuesday, July 22nd, 2025 AT 7:15 PM

13 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Most of the time this will be a problem caused by "mode" actuator. I would remove the actuator but leave it plugged in and then turn the system on to make sure it moves when working the controls. You can also move the blend door pivot by hand to see if it makes a difference. Here is the location of the actuator and a guide to go over as well.

https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

Check out the images (below). Please let us know what happens.
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Wednesday, July 23rd, 2025 AT 11:35 AM
Tiny
JUANEMMANUEL
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Okay, I just ordered it. Also, regardless of if it's just one bad actuator, would you recommend changing all of the 3 actuators on the driver side? Since they're all the same age. Thanks.
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Wednesday, July 23rd, 2025 AT 11:41 AM
Tiny
KEN L
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It would not hurt since you will be in there anyway. Here is how to reset the system so they calibrate correctly:

https://www.2carpros.com/articles/step-by-step-guide-to-reset-your-cars-hvac-system-an-essential-for-every

Let us know how it goes.
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Wednesday, July 23rd, 2025 AT 4:37 PM
Tiny
JUANEMMANUEL
  • MEMBER
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I replaced the top 2 actuators. The bottom one (AC Mode) was the only one working fine. But it still doesn't seem to blow colder from the middle and driver side vents. Could it be some sort of blockage or a problem with the evaporator itself?
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Monday, July 28th, 2025 AT 7:53 AM
Tiny
KEN L
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O ya, what happens is people drop things down the vent system which can hold the blend doors open, such as coins, toothpicks, ink pen etc. I would remove the actuator on that side and work the blend door pivot by hand, see if you can hear it close in both directions. This guide may help:

https://www.2carpros.com/articles/replace-blend-door-motor

Please upload pictures or videos in your response

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Monday, July 28th, 2025 AT 12:42 PM
Tiny
JUANEMMANUEL
  • MEMBER
  • 63 POSTS
By the way, a while back I disconnected the heater hoses from the heater core. So, I don't have a hater anymore. Would that have something to do with it?
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Monday, July 28th, 2025 AT 12:45 PM
Tiny
KEN L
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No, that won't do anything, check the blend door operation. :)
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Monday, July 28th, 2025 AT 12:52 PM
Tiny
JUANEMMANUEL
  • MEMBER
  • 63 POSTS
So upon closer inspection the middle actuator (Driver Side Actuator) was not turning at all when operating the AC settings. I tried to turn the pivot by hand and I couldn't. But with some small pliers I was able to turn it. However I turned in both directions as far as I could but there was no change in the meek airflow coming out from the middle vents.
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Saturday, August 2nd, 2025 AT 4:31 PM
Tiny
KEN L
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Hmmm this is a bummer, this means the blend door has fallen apart internally the HVAC box will need to be removed and disassembled, sorry.
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Sunday, August 3rd, 2025 AT 11:55 AM
Tiny
JUANEMMANUEL
  • MEMBER
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Ok I see. Would you happen to have a diagram if the HVAC box?
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Sunday, August 3rd, 2025 AT 11:59 AM
Tiny
KEN L
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Sorry, this is all they give us.
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Sunday, August 3rd, 2025 AT 12:09 PM
Tiny
JUANEMMANUEL
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Ok thank you for your help.
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Sunday, August 3rd, 2025 AT 12:10 PM
Tiny
KEN L
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You are welcome, please upload pictures or videos in your response of any problems so we can see :)
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Sunday, August 3rd, 2025 AT 12:41 PM

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