Jeep only blows air through defroster vents....

Detained · 10-26-2009, 05:53 PM

1997 Jeep Grand Cherokee TSi
5.8L 318
I apparently have a vacuum problem concerning the air vent gate as air only blows threw the defrost vents. Tried different switch with same results then separated the vacuum connector at the switch and see that there is no vacuum at the lines, I'm in PA. and my repair manual is in GA., 900 miles away. I pulled ALL the lower dash trim off and still am unable to completely see everywhere the vacuum lines go. Anybody know where the vacuum supply comes in at on these Jeeps so I can try and trace problem? Oh, also I found a tiny what appears to be a vacuum cap on the passenger side floorboard. ANY help here would be appreciated..... A vacuum chart for this vehicle would be real helpful if ya know where I can download one. Of course none of the problems I'm having started until I put a 4 Sale sign on her.....

TIA

Detained

skiebuster · 10-27-2009, 09:41 AM

check under the hood first for vac leaks. thats where I found mine and just had to push the hose back on to work correctly.

hope this kinda helps...

chrisdm4 · 10-27-2009, 09:30 PM

Sadly i cannot help you but I am having the same problem. So if you do find out what went wrong please let me know!

itsanxjthing · 10-27-2009, 09:44 PM

Quote:

Originally Posted by chrisdm4

Sadly i cannot help you but I am having the same problem. So if you do find out what went wrong please let me know!

x2

gully369 · 10-27-2009, 11:20 PM

I may be mistaken but I believe air only blowing out of the defrost is a default setting when there is an issue with the heating/cooling system...I remember reading about it previously but don't remember the details...

ET JEEP · 10-28-2009, 07:41 AM

Looking at a picture in my manual it looks like the line enters the cab on the passenger side next to the AC lines. There is a check valve on the line in that general location. The manual shows a few test you can do to check the ac/heater control valve. It operates with vacuum so a leak somewhere is the problem. Defrost is the default setting.

Detained · 10-28-2009, 08:47 AM

Quote:

Originally Posted by ET JEEP

Looking at a picture in my manual it looks like the line enters the cab on the passenger side next to the AC lines. There is a check valve on the line in that general location. The manual shows a few test you can do to check the ac/heater control valve. It operates with vacuum so a leak somewhere is the problem. Defrost is the default setting.

Is it possible you could scan the Vacuum diagram and the test instructions and send them to me?

Rick

Detained · 10-29-2009, 02:44 PM

Quote:

Originally Posted by Detained

1997 Jeep Grand Cherokee TSi
5.8L 318
I apparently have a vacuum problem concerning the air vent gate as air only blows threw the defrost vents. Tried different switch with same results then separated the vacuum connector at the switch and see that there is no vacuum at the lines, I'm in PA. and my repair manual is in GA., 900 miles away. I pulled ALL the lower dash trim off and still am unable to completely see everywhere the vacuum lines go. Anybody know where the vacuum supply comes in at on these Jeeps so I can try and trace problem? Oh, also I found a tiny what appears to be a vacuum cap on the passenger side floorboard. ANY help here would be appreciated..... A vacuum chart for this vehicle would be real helpful if ya know where I can download one. Of course none of the problems I'm having started until I put a 4 Sale sign on her.....

TIA

Detained

FIXED!!..........Apparently the vacuum line going in through the firewall was already broke and I didn't know it because I thought I did it while looking for the problem.......DUH!!

Thanks go out to those that tried to help!!!

Detained

10-27-2009, 09:41 AM	#2
skiebuster Member Garage is empty, add now Join Date: Jul 2008 Location: Argos indiana Posts: 204 My Photos 98 Cherokee Engine: 4.0 Transmission: aisin auto Transfer Case: not sure Front Axle: not sure Rear Axle: not sure Tires: need bigger Lift Specifications: stock, not for long	check under the hood first for vac leaks. thats where I found mine and just had to push the hose back on to work correctly. hope this kinda helps... __________________ 98 GrandCherokee LIMITED 4x4 4.0 auto 124,000 miles and counting. 99 Grand Cherokee Laredo 4x4 4.0 auto, leather, sunroof. 191,000 miles and new motor !

10-27-2009, 09:30 PM	#3
chrisdm4 Senior Member Garage is empty, add now Join Date: Mar 2009 Location: Telford PA Posts: 671 My Photos 1997 Grand Cherokee Engine: 4.0L I6 Transmission: 42RE Transfer Case: NP231 Front Axle: dana 30 Rear Axle: dana 35 Tires: BF AT 31 Lift Specifications: 4" RC short arm Misc Accessories: cragar wheels, dynomax exhaust, K&N Intake, JKS discos, Skyjacker stabilizer, Riddler Mfg Diff cover	Sadly i cannot help you but I am having the same problem. So if you do find out what went wrong please let me know! __________________ 01 WJ......97 ZJ......75 CJ5 Route 63 motorsports #248 Never run when you can walk, never walk when you can stand, never stand when you can sit, never sit when you can lay down, never lay down when you can sleep, and NEVER pass a supply of clean water.

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10-27-2009, 11:20 PM	#5
gully369 Member Garage is empty, add now Join Date: Jul 2009 Location: Fort Collins, CO Posts: 102 My Photos 98 Grand Cherokee Engine: 4.0 Transfer Case: 242 Front Axle: d30 Rear Axle: d35 Tires: 265/75/17 BFG MT's Lift Specifications: 4" OME Misc Accessories: Jet performance chip, Firepower ignition, FIPK2, 62mm TB, Hesco TBS, Cat Back, Stillen Rotors Rear	I may be mistaken but I believe air only blowing out of the defrost is a default setting when there is an issue with the heating/cooling system...I remember reading about it previously but don't remember the details...

10-28-2009, 07:41 AM	#6
ET JEEP Seasoned Member Garage is empty, add now Join Date: Sep 2009 Location: East Texas Posts: 455 My Photos 1997 Grand Cherokee Engine: 4.0 Transmission: 42RE	Looking at a picture in my manual it looks like the line enters the cab on the passenger side next to the AC lines. There is a check valve on the line in that general location. The manual shows a few test you can do to check the ac/heater control valve. It operates with vacuum so a leak somewhere is the problem. Defrost is the default setting.

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10-29-2009, 02:44 PM