So im driving down the road with no heat and windows up. Its cool out but nice, all the sudden Im feeling air, I check the ac vents and air is blowing through them. I rotate the knobs to try and stop it and its constant air flow. What happen? I bought a new vacuum line 3 weeks ago, the line from the pump to the passenger side of dash. Its all of the sudden outside air blowing through the dash vents. This is really going to mess up the ac on a hot day.

What was your ventilation setting before the air started coming out of the vents? 

 

If you lose your main vacuum supply, then all the air flow will default to the defrosters, so it sounds like you have something else going on.  Possibly a vacuum line came off of the mode door for directing air to the floor, dash, or defrosters.

 

- John

 

1 hour ago, jlwelding said:

This is really going to mess up the ac on a hot day.

 

It won't cool the cab as fast as the recirculation mode, but the AC system should easily keep your cab cool, even bringing in outside air.

 

 

Very true. It weird you got vacuum to open the fresh air flap or vacuum was dropped the door blew open. If vacuum was dropped then it should be stuck on DEF mode. There should be a few vacuum motors fresh air is over next to the kick panel. Just gotta do a dash pull.

Been a bit since I was in there last but I think its just a glove box pull to get to that actuator..

 

Also, the only thing that can stop fresh air coming in is the recirc door right? Otherwise there isn't any true "off" setting as far as I'm aware of..

 

When you put the selector into "off" does it actually shut everything off? 

There are eight positions on the ventilation switch.  @jlweldingneeds to give more information about the ventilation settings and where the airflow was going before the sudden change occurred, otherwise we are shooting in the dark trying to help him.

 

- John

Only 2 positions close outside air OFF and MAX A/C. The rest of the positions are open to outside air.

In the off position it comes through the ac vents in the dash. I pulled the glove box and Im finding things like the heater core is exposed at the top. Im pretty sure it should be  enclosed. The flap at the blower motor has a 1/2 inch gap at the bottom like it was broke off or something is missing. 

Are you meaning fins exposed? Otherwise the top of the heater core is exposed by design.

 

Half inch gap at the bottom of the recirc door is definitely something to look in to. Another thing to consider is whether your truck is running. The extra vacuum could pull the door where it needs to go..

Ok then the heater core is ok. I swore it was covered. I looked into it closer today and it looks like someone took a dremel to it and cut away at the bottom of the housing making a gap between the black plastic housing and the white door. Strange. I still dont think the gap under the door is letting air in, must be a motor out or something. Its no doubt fresh air blowing through the vents.
Thanks for the help.

Post pics? Might help narrow down the path you gotta take to fix it

Is there a how to post pics? I know years ago it was hard to post.

 

"Add files" below the text box. Then find your photos. Dont use your large size camera (64 megapixels and up) for photos, theres a size limit..

1 hour ago, Silverwolf2691 said:

Dont use your large size camera (64 megapixels and up) for photos,

Did you mean 64 KB and not MB.   

I edit mine down, on a laptop, to around 150 KB before posting. 

My cell phone (Galaxy s20+) has a 64 megapixel camera.. i know other phones are at 108 mega pixels (Galaxy s20 ultra and up i think). It (64 mega pixels) is a huge photo, roughly 6k pixels by 9k pixels, and around 10 MB in file size. 108 would be almost double that..

Yup. Same here I've got the 3:4 ratio 64 MP camera as well. I typically keep the full or 1:1 mode.

 

Samsung S21 Android.