No air through vent? Vent Problems?

It sounds like you are having an issue with the mode blend door actuator. It's a small electric motor that opens/closes to move air flow throughout the proper air ducts. Here is a tutorial to show what's involved for replacement:

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

I've attached step-by-step pictures below including its location for your specific Chevrolet truck.You will need a GM scanner to calibrate the actuator after replacement.Hope this helps and thanks for using 2CarPros.

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

When I first get in the truck the air blows fine out of all the vents. After maybe 10min it will start to blow less and less until there is hardly any air coming out. I can hear the blower motor running. When it does this I turn it on high and it sounds like something rattling in the vents by the motor but after a minute or so on high it will start blowing out fine and I can put in on a lower fan speed and it'll work fine for a few minutes and then it'll stop blowing out vents again. Blower motor has been replaced but still have same problem. Air stays cold.

I never figured out what it was. But I did realize that when the air would stop blowing through the vents the lines and accumulator would be frozen up. I read that after a while you can get moisture in the frion which will cause it to freeze and block the air blowing in. I dont have the problem any more it just went away on its own but I did go ahead a pull a vacuum and recharge the system. So I’m not really sure what it was.

Yep that is exactly what happens, when the system is low on charge the evaporator ices up and blocks the airflow. Recharge the system and the problem goes way.

Here is a guide to help you.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

and

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

I'm gonna do this and I will let you know how it works out. Nobody else has even had a possible explanation so this is welcomed information! Thanks!

Please let us know what happens so it will help others.

Cheers, Ken

OK, I showed this link to my mechanic and he agreed that this could be a possibility, so pulled a vacuum and recharged the system. Worked fine in the shop, then a couple of miles down the road it did the same thing, so this solution did not work. I now notice that I am having the same problem with the heater, or when the AC is off and it is on outside air. The vents slowly get closed while driving. Doesn't seem to happen if the truck is just idling sitting still. The fan is running strong, but it is like all the vents are closed. Sounds like it is blocked somewhere in the dash on the passenger side.

Okay it sounds like you have a mode blend door actuator that is going out. Here is a guide that should show you what you are in for when doing the job.

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

Here is what it will be like in your car (below)

The diagrams are Mode, Right then Left air blend door actuators. After replacing the actuator the system may need to relearn which can be done by removing the HVAC fuse for 15 minutes.


Please let us know what you find.

Cheers, Ken

OK, thanks. I will give this a shot!

my control panel will not switch from air to heat only blows out air vents no defrost or heat on floor?

try puling the heater fuse and see if the control will reset. if not you'll have to see if your actuators are getting power to operate. i'll send a generic pic along to show where they are....

The air doesn't blog out the dash vents. I replaced the actuator under the dash and it still doesn't blog out dash vents. Is there another actuator behind the dash or another switch or component that I am missing?

I'm not sure what blog means but if you can't feel air coming out of vents first thing that I would check is cabin air filter, if clogged with years of dirt and derby it will restrict air flow. Another thing that could be check is the blower motor.

check blower motor relay under hood as well as fuse first. pull fuse on havac inside to reset actuators.there is also a tsb on this 10240 that the harness burns up from control to resistor so the harness has to be replacedas well as resistor part can be got from gm parts direct.com costs about $175 for both so check to see if harness is damaged and you don't have a cabin filter in your truck

I have been having low air flow from the dash vents. I replaced the cabin air filter a while ago, but not much difference. The fan runs fine. I suspect a problem with one of the vent doors.

Yes, it sounds like you have a problem with the mode blend door actuator. Here is a guide which has a video that shows how to replace the mode actuator to fix the problem:

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

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken

blower is running fine but no air is coming out of any of the vents.

You have a mode blend air actuator that is out and not working. Here is a guide to help you get the problem fixed.

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

Please let us know what happens.

Cheers, Ken

The air flow from the vents is very weak, the fan motor sounds louder than normal as if air flow is blocked somewhere. I have changed out the filters which were very full of debris, with evidence of squirrels or mice. Fan output is stronger from the fan itself with filters removed and filter compartment left open.

There is an blend door actuator for the air direction mode that sounds like it has gone out. Here is a guide that will help you get the problem fixed:

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

Please let us know what happens.

Cheers, Ken

Squirrels/mice are not a good thing to have in there. Is it possible that there is other material blocking the airflow around the cores if they were inside? I would probably pull the system apart and clean it all out as both rodents can carry things I would rather not breath.

With the fan on can yo switch from floor-dash-defrost? How about hot-cold? If those work but you have low flow blockage is very likely the issue.

OK, I have located the suspect OEM actuator. Will have to buy a 7/32" or 5.5mm socket to remove.
But first let me clarify. The function switch (dash/floor/defrost) seems to be working but the air flow is considerably reduced, especially the floor vents. I believe it has improved a little since I cleaned all the outside vent intakes and the filters(which are new but did have a little bit of debris collected). The blower motor sounds very loud if I step up the speed past first position, the higher the speed the louder it gets. Kind of a roar! To me this indicates a blockage but my question is WHERE? How do I locate it and what are the likely suspects? Oh one more thing, whit the filters removed the fan seems to be blowing quite a bit of air but it is still much louder than normal.

As the mode doors seem to be working I suspect the blockage is down in the blower area itself, around the squirrel cage. Item 20/21 in the image. I would drop the blower motor out the bottom and see what you find. It is real simple, remove the sound deaden-er cover screws, disconnect the wiring, drop the cover off, release the tab and turn the motor counter-clockwise to disengage it from the housing. Maybe put a plastic bag under it, just in case it has debris in it. With the blower out you can use a light and a vacuum hose to clean out the housing of whatever you find.

Can you suggest a good way to remove the blower cover screw that is behind the casing. I can't see it but I can feel it. So far none of my socket/extension combinations will allow me to get in there, the clearance is very small.

I use a thumb ratchet on locations like that. Never had a real problem, but I also have a tool box the size of your truck.... Makes finding the right combo a bit easier.

I was thinking of trying a flex shaft extention.

Might work. Without it right in front of me, my mind draws a blank.

I look at a fastener and my mind says "get this, this and this" to get that out/off. Being in the rust belt means this process usually includes either a hammer or torch somewhere along the line !

Plus I have a drawer full of "custom" tools. Stuff that has been cut, welded, bent or all the above, to fit into spots that nothing else fits.

One item I've found real helpful is a mirror or small digital camera or a borescope. I can set up a light and the camera and "see" what I'm doing in places you just can't see with your eyes. Makes some jobs easier.

Thanks for the ideas! I will try the mirror, a small flashlight and a flex extension. I'll let you know what happens!

Well my flex shaft attachment for my ratchet finally got here (there was no room for any other approach to the screw behind the housing) and I took the bottom plate off under the fan motor (I was expecting to be able then to drop the motor but it only exposed the very bottom of it. Please explain again how to get the fan out. Is there a video or some photos available perhaps?

There is a tab you press in and rotate the motor counter clockwise and the blower drops out. Sort of a child proof blower....

there is no air coming out of the vents, fan works okay. no matter where you put the control vent, floor, or defrost no air comes out vents.

try pulling heater/A/C fuse inside truck It may reset actuators. if not it may be the mode actuator that is bad. it is above gas pedal. See picture.

The only thing i don't like about the truck is that when you turn on the a/c, you can hear it blowing really loud, but if you put your hand to the vents, you only feel a little bit of cold air. My dad said it may be dirty a/c coils. I'm open to any suggestions please! Texas weather is brutal without an ac!

The truck may have a passanger compartment filter. It is on the rightside under the dash.If it is pluged the air will be affected. Remove the lower kick panel and you should see a cover.Remove the cover and then slide the filter down. You would be better off installing a new one verses leaving it out or trying to clean it....I attatched a pic to show you where it is

#1 is the cover #2 is the filter Cly

Thanks! I took out the filter and it is blowing hard again! This truck used to be used by my dad's logging business and had the air filter completely clogged with large chunks of dirt! I'm going tomorrow to pick up a new filter thanks a million!