A/C only coming out of defrost vents

[DLStryker]

I'm sure this has been been discussed before, but I could not find anything using the search. I am new to this forum as of today.

My A/C in my 2000 Grand Chereokee blows cold, but only out of the defrost vents..... no matter where I have the position selected. Does anyone have a suggestion of what the problem may be. Do you think the Blend Door Actuator needs replaced?

Thanks in advance for your help.

[SvenskaJeepGuy]

the defroster is the default to any failures in the system

[Scottina06]

blend door is the most common

[ducks unlimited]

blend door is the most common

x2 sounds about right :thumbsup:

[DLStryker]

blend door is the most common

As in you think the blend door is physically broken. Do you think the actuator is working, but blend door itself is physically broken?

[SvenskaJeepGuy]

in my old WJ the blend door broken and the air would only come out of the defroster. i traded in the jeep before ever fixing it. there is a replacement on ebay but i cant remember the name of it. it replaces the junk plastic parts that jeep used with metal parts. u have the remove the glove box and dash to install it i think.

[Frango100]

If the problem is that hot or cold air only comes out of the defrost vents, the problem is the mode door. The blend doors only take care for mixing hot and cold air. Which system your WJ has, the manual system or the automatic one. In the manual system the mode door actuators are vaccum controlled, but in the automatic system (with the dual zone control) the mode doors are electrically controlled. For the last system you can find here below how to get the fault code(s) out of it. Because the list of codes is quite long, i won't put it here, but just let me know what you find and i can tell it to you.




ENTERING THE AZC SELF-DIAGNOSTIC MODE
To enter the AZC self-diagnostic mode, perform the
following:
(1) Depress the a/c and recirc buttons at the same
time and hold. Rotate the left temperature control
knob clockwise (CW) one detent.
(2) If you continue to keep the a/c and recirc buttons
depressed, the AZC control module will perform
a Segment Test of the Vacuum Fluorescent (VF) display.
In the Segment Test you should see all of the
display segments illuminate as long as both buttons
are held. If a display segment fails to illuminate, the
vacuum fluorescent display is faulty and the a/c
heater control must be replaced.
(3) After viewing the Segment Test, release the
A/C and Recirc buttons and the display will clear
momentarily. If a 0 is displayed, then no faults
are set in the system. Should there be any faults,
either 9current9 or 9historical9, all fault codes will be
displayed in ascending numerical sequence (note no
effort is made to display fault codes in chronological
order). Each fault code is displayed for one second
before the next code is displayed. Once all fault codes
have been displayed, the system will then repeat the
fault code numbers. This will continue until the left
side set temperature control is moved at least one
detent position in the CW direction or the ignition is
turned 9OFF9.

[DLStryker]

Frango100, thanks for your response. I do not have the dual zone control system. So I am assuming I have the manual system. Your instructions on getting the fault codes are not applicable to my system. I do not have a recirc button. Recirc is actually one of the selctions on my round knob (the knob that selects recirc, dash vent, floor vent, defrost, etc.).

With this information, could you provides some additional advice?

It would be very much appreciated.

Thanks

[Joe in PA]

Check all your vacuum lines for a leak and pay real close attention to those on the drivers side of the engine compartment. ;)

[SvenskaJeepGuy]

Check all your vacuum lines for a leak and pay real close attention to those on the drivers side of the engine compartment. ;)
............now i remember the problem in my WJ i had a busted vacuum line. i replaced it and it worked good for over a year. then the actual doors broke and i left it broken until i traded it in to the dealer.

[Frango100]

I have no experience myself on the manual system, what i tell you i just red in the WJ service manual. But as the other guys already mentioned, the problem can be a broken or disconnected vacuum hose in the engine bay or at the cabin side. You could remove the heat/airco control panel and find all the vacuum hoses connected to the mode switch. Attached a schematic for which hose is for what. I would first check if vacuum is available at the switch by disconnecting the vacuum line for the vacuum supply. If this is ok, you have to go to the vacuum valve. Maybe someone else could guide you how to get to tis valve.

[SvenskaJeepGuy]

here is the improved part it you find it is the door...........

http://cgi.ebay.com/ebaymotors/Blen-Dor-Jeep-Grand-Cherokee-Blend-Door-Heater-Repair-_W0QQcmdZViewItemQQhashZitem3eef1e1cd6QQitemZ27029 9700438QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

if it is the door you might hear a slight rattle when the jeep is at idle

[Frango100]

Just looking at the schematic i had send to you before, and indeed when there is no vacuum available the defrost mode is the only available. So most probably the fault is somewhere with the vacuum supply line between the engine and the mode switch.

[Kruul]

I just fixed this on mine today. There was a very small rub spot in the small line just before it enters the firewall.

You can start where the vac line comes off the intake manifold and just trace it back. That line runs far beyond the spot where it T's off to the a/c. The fix cost around 4 dollars. Good Luck!

[SvenskaJeepGuy]

There was a very small rub spot in the small line just before it enters the firewall.

i think there is where my wj was damaged too. it was a super cheap fix the first time, but once the doors broke it was expensive so i just left it broken

[DLStryker]

Check all your vacuum lines for a leak and pay real close attention to those on the drivers side of the engine compartment. ;)

You were spot on Joe!! Vacuum hose on the drivers side that connected to the intake maniflold was disconnected.

Thanks to everyone for their help!

DLStryker

[SvenskaJeepGuy]

dont you just love a simple fix?

[Joe in PA]

Great to hear the leak was easy to spot and even easier to fix! :D

[DLStryker]

dont you just love a simple fix?

YES!!!! Luck was on my side this time. Easy to fix and no cost! I had stopped at a repair shop and they said the repair would be between $300 to $1,600.

[SolarWar]

would this work for a wk as well? ive got an 06 GC laredo, and the air come out of the defrost and the floor vents all the time. if i switch it to the dash vents, they will work, but then its all three locations that blow. if i switch to the defrost or floor vents the only thing that changes is the dash vents close.

Chris