Air only blows out of the defrost vents ** yes, I tried the search function **

Ok... so I can only get air to blow out my defrost vents. The dash vents will not blow any air. I checked the vacuum line that runs into that ball behind the bumper. No leaks! There is a T in the line with a plus in it. when I pull the plug off the T, I can feel suction which confirms there are no leaks in this line.

Anyone else know what t could be? Someone suggested I check the blend door actuator under the dash. I am not sure what I am really looking for?

Any suggestions????

Didn't mention what year, But i'll assume its before the dashboard got all chryslerish.

At the passenger floor mat, youll see a little ball like cover. You can move it out of the way, or just unscrew it. Behind that you'll see the actuator with a single orange vacuum line going to it, unplug it and see if you have vacuum. If you do, then the actuator itself is bad (its replacement is straightforward) If not, look for a leak under the hood to the right of the coolant bottle on firewall. Where two lines enter through the firewall-mine was busted there.

it miet be a door not working

Loss of vacuum anywhere in the HVAC system will make the vents default to defrost. Look for leaks in the vac lines running along the passenger fender in the engine bay and under the battery to the vacuum reservoir.

Corrosion and failure/breakge of those small vac lines is comman and an easy fix.

Yup, you've got a vacuum leak. You smack the reservoir lately? It's mounted in the front bumper.

same problem, my break was by the battery, vacuum hose takes a tight turn right there and is prone to fatigue and cracking

is it suppose to be a little bit loose i have the same problem im about to go look at the reserivor but the line on the drivers side, coming out of the ac unit is a little loose could this be my problem what about the thing underneath the dash on the passengers does it have some kind of auctuator in it or something thanks guys

I had this problem after I installed my new CD Deck. The problem was when I put it in I messed up all the linkage that controls the AC/Heat and which air vents you want. Check that out.

xjboy said:

I had this problem after I installed my new CD Deck. The problem was when I put it in I messed up all the linkage that controls the AC/Heat and which air vents you want. Check that out.

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No I bet it is the actuator either is bad or is failing to get vacuum from a bad or loose line. Trace the vacuum lines and replace or repair them all to end up with a good running XJ.

I've read threads in the past where they find that the hoses have came off of the controls. If you don't find anything obvious under the hood, might be worth the time to pull the dash bezel and the AC controls to take a peek.

Mine does the same thing,but only when the jeep is off. So make sure it's running. If it still does it while running it has to be a vacuum I would think.

CrunchnMunch said:

Mine does the same thing,but only when the jeep is off. So make sure it's running. If it still does it while running it has to be a vacuum I would think.

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You've got a vacuum leak too.

thanks guys for all of the help this site is just the best ever ill try it today and by the way my 4wd light dont come on hope it works though ill find out today when i get out of school i got a creek behind my house can't wait!!!

Hmmm my A/C blows out of the vents, but when I put it in cruise control at 70 mph, I get light air from the vents, and heavy blowing air from the defrost vents.

If I hold the speed manually I get more air flow from the vents, and less from the defrost vents.

I'm going to check the hoses mentioned above, but if this rings a bell for anyone...

muckleroy said:

Hmmm my A/C blows out of the vents, but when I put it in cruise control at 70 mph, I get light air from the vents, and heavy blowing air from the defrost vents.

If I hold the speed manually I get more air flow from the vents, and less from the defrost vents.

I'm going to check the hoses mentioned above, but if this rings a bell for anyone...

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I had the same problem. It was a very slow vacuum leak in the AC vacuum lines. Mine was at the entrance near the firewall, passenger side near the expansion valve and heater hoses, and it was a brand new piece of vacuum hose I installed the week before that turned out to be defective on the ID bore of the hose of all things! Liked to never found that bloody leak. My doors would switch from Max AC to defrost, thought I had an electrical issue, but it was triggered by pushing the gas peddle. Guess what, you push the gas peddle and engine vacuum drops!

OK.... so IU pulled a bunch of stuff off the Jeep today to try and solve the problem. I didn't fix it, but here is what I found:

-The vacuum T by the battery has good suction coming from it. The leak isn't there.

- The vacuum T where the line goes into the firewall also has good suction. The leak isn't there.

-There is a 6 line vacuum plug behind the heater knobs. There is no vacuum at those lines.

- I found 4 actuators that control the different vents. I push them manually and they all change the direction of the air flow, so I think they are OK.

-There is a piece that mounts to the firewall under the hood. It has an electrical plug running to an A/C components. There are teo large vacuum lines running out of it. It was making a wierd clicking noise. I pulled the two lines off and there is no vacuum. Is this a proiblem.

-The one question I have: how many lines run from the engine compartment through the firewall that control the heater/ AC controls? from what I see there is only one and it has vacuum.

All of the vacuum lines under the dash are buried deep in there. If I need to view them any further, I will likely need to start unbolting the dash. I am stumped at the point. any ideas?

What year is it???

Sounds like you are missing one vacuum line at the firewall on the AC. There should be 2 small vacuum lines next to each other runing through the firewall (at least mine, 85-89 have 2 lines).

If any one of the diaphrams is busted inside the actuators, it is your leak point! Only way to test each diaphram may be with a hand vacum pump and hose. You should be able to pull and hold a vacuum on each actuator diaphram. I had one go bad on mine.

I'm guessing your year is later than Mike's. The one you have comes from the bottle and supplies vacuum to the AC/heat selector. You must have a line loose or cracked.

My 88 and Mike's have 2 since the other goes to the heater valve which is also vacuum operated.

My 85 and 87 do not have the vacuum operated heater valve. I think it was first used in 88. I have never quite figured out why there are two vacuum lines in the firewall on mine, maybe the second one is cruise control brake on my 87? All I know is I had to get vacuum on both lines on my 85 to finally get all my damper doors to work right. That 85 must have had 30 vacuum lines and vacuum valves on the 2.5 L gasser. Must have been a nightmare for vacuum leaks to diagnoise. Cruise does not work on my 87.

Saudade said:

I'm guessing your year is later than Mike's. The one you have comes from the bottle and supplies vacuum to the AC/heat selector. You must have a line loose or cracked.

My 88 and Mike's have 2 since the other goes to the heater valve which is also vacuum operated.

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Ecomike said:

My 85 and 87 do not have the vacuum operated heater valve. I think it was first used in 88. I have never quite figured out why there are two vacuum lines in the firewall on mine, maybe the second one is cruise control brake on my 87?

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Hmmm.. Not sure about what year the vac heater valve was first used. Those are the 2 lines coming from my '88. My cruise works intermittently. I think my prob is electrical. I'm still chasing it around.