No air out of dash only defrost

[CrzyEX00]

My air conditioning only blows out of the defrost. the switch is on max a/c and no air comes out of the dash. ive checked for vacum leaks and couldnt find any. i was told there is a box behind the glove box that a cable goes into and the cable sometimes breaks but i couldnt find a cable that would open and close the air duct. i live in florida and its killing me! help please
thanks

 

[scucci]

Sounds like a vacuum motor is not receiving vacuum. There are a couple of them mounted on the plenum box. One is the Defrost/Panel motor and that is the one that would cause your symptom. Try manually moving the levers from them, one at a time to see if the panel vents now work. That will let you know which motor it is. Then check for vacuum to the motor. No vacuum means a broken line or bad vacuum switch or leaking/disconnected vacuum reservoir. Sorry I am unable to tell you exactly where the motors are, but they are under the dash on the side of the heater/ac plenum box. If the motor has vacuum going to it then it is a bad motor.

 

[BrooklynBay]

Check for cracked plastic vacuum tubing near the servo pistons.

 

[celly]

Check out this thread. I just solved the same problem by replacing the vacuum reservoir ($25 part, pictured below, the "globe" thing). Many others have solved their problems by plugging in a disconnected vacuum line or patching a pinched/melted line.

 

[CrzyEX00]

i still cannot find and holes leaks or cracks in any of the vacum lines. if the resivoir ball was bad would the a/c still blow cold?

 

[Turdle]

i still cannot find and holes leaks or cracks in any of the vacum lines. if the resivoir ball was bad would the a/c still blow cold?

Yes
Vacuum powers only the vent function. You have a vacuum leak--blockage somewhere.

Do you have good vacuum at the firewall connector?

 

[CrzyEX00]

i checked for vacum on the inside of the firewall behind the glove box and i felt no vacum

 

[Turdle]

i checked for vacum on the inside of the firewall behind the glove box and i felt no vacum

There ya go--now trace those lines back under the hood-
they run along the inner fender well to the globe, then across to engine bay for the source vacumm. Somewhere it is broken, or, disconnected. You might have a leaking reservoir globe also. It is easy enough to get one at a junk yard.

 

[CrzyEX00]

ok thanks ill keep u posted on how it goes. and thanks again

 

[coondog491]

the same thing happened to me,

except it was a plastic bag that got sucked up there hahaha

 

[CrzyEX00]

i finally got my a/c working. the vac line running to the firewall was melted and closed the line. hooked a new line up and now the dash a/c works. thanks everyone for your help

 

[BrooklynBay]

Thanks for the update! It sounded like it was a vacuum related issue.

 

[thegarman]

A/C only out of the dashboard defroster vents!

I've read countless threads on this forum to solve a couple HVAC problems with my 1999 Explorer Sport. I found a vacuum leak that kept the air from coming through my side and floor vents. (Apparently, if there's a vacuum problem with your HVAC system, the default is for all A/C to flow thru the defroster vents.) I followed the lines coming out of the vacuum reservoir (located behind the passenger side headlight and accessible from underneath - there are two 8mm and two 10mm bolts to remove and access this black, round reservoir.) All I really needed to do was trace the two little black vacuum lines from the reservoir, because I found one connection had pulled off. Once I plugged it back on, the A/C came through ALL my various vents!

As a "newbie", I can't seem to be able to post a picture of the loose connection, but the black vacuum line turned into a red line and the connection that pulled off was off the passenger side of the valve cover near the "Add Engine Oil" cap.

 

[BrooklynBay]

Click the go advanced icon on the lower right hand of the quick reply box, then click the manage attachments icon to upload a few pictures.

 

[chicomab]

No air coming out of vents

Had this same problem. My leak was at the vacuum hose rite in front of the motor drivers side. Plastic hose broke off.