Richard (4.229.207.63) - Wed Aug 20 10:02:21 2008

My '04 fan position switch won't work (go from floor to dash to windshield, etc.), and the cruise control won't engage. I'm told both are due to a vacuum line problem, but I can't find a disconnected vacuum line anywhere. any suggestions?

Reply #1 Patrick (215.1.0.38) - Tue Sep 9 11:52:18 2008

I have the same problem (and internet searches suggest it is fairly common). Does anyone have a vacuum diagram? I don't know where to check for these leaks.

Reply #2 Jerry (24.180.238.26) - Wed Sep 10 07:11:24 2008

Hope this helps, I had the exact same problem with my 2001 Grand Cherokee, ((fan position switch won't work (go from floor to dash to windshield, etc.)), and the cruise control won't engage. I'm told both are due to a vacuum line problem, ). I fixed mine by replacing 1/4" hose located directly under battery mounting pan. Takes a little work but might be worth it.

First remove battery. Then remove pan, you'll need a deep socket 10mm with extentions to get at one mounting nut. Remove two nuts holding cable to fuse/relay box attached to pan. Move pan out of way. The hose that's causing all the problems is about 6" long going to servo. Replaced hose ($.77) and it took care of both problems. Total job took about 1 hour. From what I have been reading this is the hose that's causing everyone problems.

Reply #3 Tim (68.63.212.165) - Sat Oct 4 12:05:23 2008

I followed your insturctions and fixed both the cruise control and now air is blowing out of all the vents. Thanks for your help. It took me about and hour and only cost $1.00

Reply #4 Mark McClure (68.55.168.189) - Sun Oct 5 18:46:33 2008

I am having the problem with my cruise control not engaging. It turns on (the cruise light shows up at the dash) but it wont engage a speed. The jeep is a 2001 GC Limited.

Before I go this work I guess I am looking for a little more explanation on whats going on.

Thanks,

Mark

Reply #5 Gennie (70.243.60.129) - Mon Nov 3 14:20:40 2008

For what it's worth, I'm having the same air flow, cruise control problem on my '01 Jeep. I knew it was the vacuum but I thought it was a hose inside the dash and would have to take it in to get fixed. I will try the suggestion made by Jerry. Hopefully that is all it is. Thanks.

Gennie

Reply #6 Dave (99.190.91.231) - Sat Nov 22 13:10:28 2008

I have the same problem but with a 1987 Jeep Grand Wagoneer.

Reply #7 Pete M (72.219.152.117) - Sun Nov 30 13:16:50 2008

Guys,

2001 Grand Cherokee, 4.7 V-8

Same Cruise Control problem except the air/heat controls work normally. Dash light comes on but the Cruise Control will not engage.

(that may not be good, if the heater/air control stuff works it may not be the simple vacuum line under the battery someone described )

Dash light comes on but the Cruise Control will not engage.

Coincidentally, a month ago I removed the throttle body for cleaning which requires unclipping the two flex cables. Did not realize the Cruise Control was in-op for a month as I wasn't on the freeway to set it.

RELATED PROBLEM? Had the fuel pump/filter replaced last week discovered the Overdrive will not stay engaged...slight load ing and it disengages.

Wondering if the Cruise Control systems and O/D systems are related.

Thanks

Pete

Reply #8 Tim (67.175.90.140) - Thu Dec 4 23:58:21 2008

Have a 1999 Jeep Grand Cherokee Limited with Dash Control issues.

I will check the cruise control to see if the vacuum line is an issue. Thought the Dash control needed replacing. Expensive if that. $400 for the part alone. Thanks for the line idea.

Tim

Reply #9 craig (98.245.91.34) - Wed Dec 10 17:34:16 2008

I tried the solution of replacing the vacuum line under the battery pan. I had odd results that I'm hoping someone can offer a next step solution.

After replacing the line, I did a temp hookup of the battery and fuse box to see if it did the trick. The vents worked great!

I reinstalled everything more permanently, and when I restarted the Jeep the vents were back to only blowing out of the defroster!

I took it for a quick check of the Cruise Control, and that was fixed and working! Without removing the battery pan, I can see the line connected correctly on both ends.

Any thoughts?

Reply #10 Pete M (72.219.152.117) - Thu Dec 11 19:30:25 2008

see reply #7 by me, 2001 Grand Cherokee

Same CC problem everyone is relating...indicator light goes on but won't engage. Replace the virtually inacessible vacuum line about 5/6 inches long, 1/4" hose

Glad to have help to hold wiring stuff out of the way to get the battery tray up. Did not expect to have to unbolt the buss-bar from the fuse box, took us about 2 hours moving slowly.

Chrysler used very cheap all rubber hose...it does not have any layers of fabric to keep it from cracking...poor choice of material. Used fuel line for the replacement.

Did not have the heater door problem someone else has mentioned so I can not offer any help there.

Thanks for the help.

Reply #11 Clark Neal (68.154.185.77) - Wed Dec 24 17:05:12 2008

I have a 93 GC limited and the fan blower will not engage on any speed. Also if you put the switch on auto, still nothing. any suggestions on parts to start with?

Reply #12 tony (72.74.102.96) - Thu Jan 15 11:30:24 2009

I HAVE A 2001 JEEP GRANDCHEROKEE LIMITED 4.7L V8 WITH A HEATER

CONTROL PROBLEM THE BLOWER MOTOR WORKS AND THE SELECTING VENT

FLOOR AND DEFROST ALL WORK BUT NO HEAT TEMP BOTH LINES TO MY

HEATER CORE AND HOT WOULD THE SWITCH BE BAD??

Reply #13 bill (71.57.34.157) - Sun Jan 25 12:26:10 2009

I have a 86 grand wagoneer. Heater motor is running fine but nothing is blowing out of any of the vents...it seems to be blocked ..the cruise isnt working either. Thoughts?

Reply #14 michael (80.254.146.36) - Tue Feb 3 01:37:16 2009

I have a 3.7l cherokee jeep 2002 and my fan only works on no 4. It did work on 2.3 and 4 but now over the last couple of months its down to just working on setting no 4 the high speed blower? Anyone had this as worried that my fan will stop working all together?

Reply #15 John (199.159.177.7) - Mon Feb 9 15:55:45 2009

Take off the passenger headlight. Behind it is a small vacuum hose about 4 inches long. Mine was torn at both ends. Replaced it and everything works great.

Reply #16 Peter Clark (222.152.102.188) - Sat Feb 21 23:19:26 2009

The vacuum line was the problem on my 2001 G.C. Heater fan worked all speeds. Turning the control knob from face to feet to defrost had no responce.

The vacuum hose had come off a manifold near the firewall on left side of vehicle. A hose about 1cm goes into a very small hose before going through firewall. Check that join also.

Reply #17 Rick Martinez (67.61.43.144) - Fri Feb 27 00:24:56 2009

Mine is a 1997, I had the heater control, and the CC prob. Checked all vac. found a valve on the side of the intake, its was cheap @ autozone, replaced it fixed the heater problem but still no cc. checked the hos under battery box, good no leaks. it's connected to a box on mine when I pulled it off I heard a short hiss, it was ok. guess I'll B looking at the module or ... Micheal, with the fan problem, check the switch.

Reply #18 Rick Martinez (67.61.43.144) - Fri Feb 27 11:53:37 2009

Replaced the brake switch, (brakelights were still working) and now I have cruise control. There is a circuit for the cruise that wasn't connecting, the switch is selfadjusting, and the pedal wasn't engaging it when returning. Anyway the cruise is working. It's only a $12. part at auto zone, worth a try.

Reply #19 Flynn Davis (66.232.244.45) - Sun Mar 15 14:01:08 2009

I'm having a similar issue with my 2005 Jeep Wrangler 'X'. My fan only blows out the defrost ducts, no matter what position the switch is in. All the different speeds work, it's just the positions. Was wondering if anyone had any advice or possible links to diagrams that would help?

Reply #20 sparky (24.45.129.38) - Wed Mar 18 20:58:42 2009

anytime the 'defrost vents' is the only air that comes out, it's a vacuum leak, so it's time to start examining hoses and pulling vacuum on segments of them when they run to more than one location, and see what gives. the hose under the battery box is not the only culprit for this, the real brittle and or ty plastic tubing that Jeep likes to use between the valve cover and the intake manifold, as well as the cheap rubber transition pieces from both the front and rear valve cover ports, are also very suspect at this point. bad news is that Jeep wants a lot of money for this cheap garbage and they should be drawn and quartered for making such crap and putting it in their Jeep product line. anyway, be prepared to buy 'real' hoses from either a boat dealer like West Marine or somewhere that will sell you something that will last more than a season or two and won't cost a fortune to replace. also, be prepared to use your mouth as the 'vacuum' test source if you don't own a small, hand held vacuum pump with vacuum gauge on it, you can accomplish the same kinds of checks for hose integrity without such expense.

Reply #21 Jerry R. (173.105.95.18) - Thu Mar 19 17:47:33 2009

Had the same problem with a little different twist on my 03 GC Larado. Had a check engine lite and also no cruise control and stuck on defrost. Many thanks to the above contributors, I found a bad rubber connection on the drivers side and replaced it, cured the check engine malfunction. Followed the instructions and replaced the 6 inch hose under the battery case and was thrilled to find I now can control the air and also have cruise control. Unfortunately, my check engine lite has returned. Any ideas?

Reply #22 Julie (70.172.223.239) - Sun Mar 22 13:30:35 2009

Hey guys I have a 2004 grand cherokee jeep all the options... anyway lately my vents are not working well all except the defroster under the windshield! and the cruise control doesnt work any thoughts???

Reply #23 Brady (24.167.181.182) - Sat Mar 28 09:51:09 2009

just wanted to let you know that this forum helped me a lot when my 2004 GC had the same problem with the CC and heater controls. found that a vacume near the rear of the intake had fallen off. its about 4 inches long so you guys can look there too if you have a problem. my GC has the 4.0

Reply #24 curly (76.4.170.248) - Sun Mar 29 17:26:11 2009

help, 03 grand cherokee check engine light on, have reset several times along with replacing three hoses, have look all over the engine for any others, wondering about the hose under the battery?

Reply #25 Brett C (12.173.196.210) - Tue Apr 21 14:34:35 2009

I had the same problem with both my C.C. and defroster switch. I located the black hose underneath the battery. It actually cracked off to what ever it connect's to behind the passenger headlamp. I was able to plug the hose end to get my defroster to work, but the way it broke off im unable to connect it back to the part it hooks too. Does anyone know what this part is called? I still have no cruise control. Thanks

Reply #26 Chuck (67.96.104.4) - Mon Apr 27 06:24:24 2009

Had the same problem with fan position switch and cruise. I started by taking out the battery box as Jerry suggested. All the hoses looked fine. I tracked the hose back to the engine - left side under the throttle body - and found it was disconnected. I reconnected the tube and it all works.

Reply #27 Greg (131.191.48.186) - Mon May 18 01:15:53 2009

Fine advice fellas...

I'll give it a go!

Reply #28 Tim (64.9.31.142) - Mon Jun 8 08:29:59 2009

I have a 97 Jeep GC with the CC and heater switch problem. Can someone help me on the location of where the hose connects to under the battery? When I pulled the battery the end of the hose was not connected to anything and I can't seem to find where it goes. I also found a line coming from the front differential on drivers side that isn't connected to anything. Thanks.

Reply #29 Bernie (65.29.79.87) - Thu Jun 11 09:57:09 2009

I had the same problem with my '04 GC... Fan mode and CC not functioning properly. Found brittle and broken vacuum line leak under battery pan. My advise is to follow reply #15 from John and remove passenger-side headlamp assembly to inspect vacuum line under battery pan before taking the battery and pan out of the vehicle. The 4" line on my vehicle was easily replaced through the space behind the headlamp. 10 minute repair v. 1 hour repair. Thanks John!

Reply #30 Lou (24.190.133.242) - Mon Jun 15 08:15:50 2009

I have a 2004 Grand Cherokee Limilted with dual temp. controls. Fan stopped working, no matter what position I set it at. I've had this problem twice before, the Chrysler dealer told me the climate control unit had to be replaced at a cost of $950.00. This will be the third one to be replaced.

Has anyone got an idea why this is happening, is this a common problem?

Thanks,

Lou

Reply #31 Larry Anderson (74.194.117.88) - Thu Jun 25 12:56:42 2009

This forum very helpful. Self inflicted CC problem. I tow my Grand Cherokee and was installing a brake lite monitor for my motorhome. Needed to splice into brake output wire at brake switch. Had to remove break switch to identify wire. When brake switch re-installed, no CC. After reading forum, removed brake switch again found short in CC output wire at brake switch. Re-installed brake switch; all working fine. If CC quits again, may need to replace switch to be sure CC output wire is perfectly secure. As long as it works, won't worry about it.

Reply #32 tom stark (67.48.237.139) - Sat Jun 27 15:22:18 2009

Thanks to Jerry in reply #2. It solved my problems with the vents stuck on defrost and cruise not working on my 2002 Grand Cherokee.

Reply #33 Tina (69.137.231.152) - Mon Jun 29 20:11:31 2009

We had the same problems with our A/C and the cruise control. We performed the recommendation of Jerry to remove the battery and battery tray to find the dry rotted hose. We now have full working A/C and cruise control! Thank you so much!

Reply #34 Larry Anderson (74.194.117.88) - Mon Jun 29 20:52:27 2009

Reference reply #31 - Spoke too soon. Replaced brake switch and CC operated great for a day. Now the dash light only comes on momentarily, then goes out. The momentary lighting generally occurs right after having started the car. After that, can get nothing from on/off switch on steering wheel. Don't think it's a fuse (can't find one)or I wouldn't get the intermittent light. Anyone think it is vacuum? Visible lines seem to be connected and A/C controls all work properly. Need some ideas.

Reply #35 Scott Salisbury (173.119.179.144) - Mon Jun 29 21:54:05 2009

Reference #23, Same problem, stuck on defrost, cruise control would not set, , , , Vacuum hose disconnected at Manifold, Thanks for the posts.

Reply #36 Dave (208.58.46.77) - Fri Jul 3 01:12:04 2009

04 Grand Cherokee- Cruise not working along with the fan selector issue. It was a vacuum line that had come loose from right underneath the throttle body. THANKS ALL

Reply #37 Tony L (99.141.142.212) - Sat Jul 4 13:07:16 2009

The removing of the battery and pan on my 04 Grand Cherokee was my problem. For the others, check the vacuum line on the throttle body. Sometimes a small clamp will do the trick.

Reply #38 NRK (163.234.185.201) - Mon Jul 6 12:51:14 2009

Lou,

I hope you have fixed your problem. I had the same problem with my 99 Jeep Grand Cherokee Ltd. The fan blower stopped working and AC and heater wouldn't work either. On top of that Texas summer 105 F outside.

I suspected the problem with blower motor, Climate Control unit(CCU) and Blower motor resister(BMR - this is right under the glove box). It turned out to be BMR(cost anywhere from $50 to $120 depending on where you buy). On top of that, the ground wire on connector to the BMR got burnt.

My solution. I got the new BMR, insulated the connector wire properly. You can also solder the 3 wires directly into the BMR male extentions.

Remember the CCU would not work if the BMR is bad. You will not get power to CCU either. Total cost to fix was about $130.

If you are still experiencing problems it could be your blower motor($40-$80) or the CCU($150- $200 on eBay). CCU is very easy to replace.

Hope all this information helps.

Reply #39 Tom (98.192.198.243) - Mon Jul 6 16:20:35 2009

Hope someone can help with this issue. 2006 G. Cherokee, turn the CC on, hit set for the speed I want, engine kicks in like I floored it and keeps going. I have to turn it off to stop it or I would be up to 100 in no time. Can't set the speed, can't hit the DECEL button, wont do anything really, cuts the engine for one second then back to floored mode again. Fans and defrost are working fine.

Thanks in advance.

Reply #40 Tom (98.192.198.243) - Mon Jul 6 16:51:16 2009

For the above post 2006 CG, CC issue, V6 3.7 if that makes a difference. Thanks.

Reply #41 John Osborne (98.215.198.233) - Thu Jul 9 13:25:56 2009

The blower fan on my 02 GC Limited keeps kicking on and off, this happens when I change the settings ( either the vent selection or the fan speed ). To get it right again I have to shut the HAVC off and back on repeatedly until it stays working. I was thinking it might be the Blower Motor Resistor or the Blower Motor itself. Any suggestions? Thanks

Reply #42 Barry Malone (75.118.212.196) - Thu Jul 9 15:42:52 2009

I have a 97 GC that also is not blowing at all or blows sometimes and shuts off. I replaced the motor assembly and it worked perfect until i came back out the next day and nothing came on, i can feel the vents getting cold but no fan whatsoever. Is the 97 blower setup similar to the newer year models? Where is the resistor located? any other info would be a great help. Thanks

Reply #43 John Osborne (98.215.198.233) - Sat Jul 11 10:39:22 2009

Post #42 the resistor on the 02 model is located just to the left of the blower motor. If you follow the lead from the motor it should lead you right to the resistor. If yours has manual climate control it might be shomewhere else...Hope this helps.

Reply #44 Dave (68.63.109.131) - Sat Jul 11 17:06:42 2009

Thanks Jerry! The cracked 6 inch vacuum tube was under the battery tray like you said, it right behind the headlight on the passenger side. It was really dry rotted and cracked for being a 2002 Jeep Grand Cherokee Laredo.

We replaced it with a fuel line since none of the auto part stores had vacuum lines, it should last a while, there not enough pressure for it to collapse.

I was so surprised that one vacuum line controls both the cruise control and air vents. Our cruise control would light up but not activate, and only the defrost vents worked, with very little air coming out on the floor.

Anyone who has this issue, check under the battery tray first, before pays tons of money on a mechanic.

- Dave

Reply #45 ray rodriguez (67.8.116.137) - Tue Jul 14 19:33:23 2009

where is the relay switch for the fan motor located on 2002 jeep lerado

Reply #46 Mitch (208.107.83.165) - Sat Jul 18 13:20:24 2009

All of my fan positions are working correctly but the CC doesn't work. The CC light comes on but wont engage. Any ideas before I spend a couple hours removing battery pan and hose???

-Mitch

Reply #47 iceman55 (24.209.191.146) - Wed Jul 22 21:29:44 2009

I have a 97 grand and need wiring schematics. The vacuum line from the intake to the cruise has a t the has snapped off, no idea where it goes

Reply #48 mattfo (24.56.224.164) - Tue Jul 28 09:53:45 2009

97 gc hose under battery tray is good but not conneced to anything. small line going thru fire wall is broken. how do you get at it from inside? can I find a new one?

Reply #49 Jester (12.238.61.2) - Fri Jul 31 21:17:08 2009

I had the same problem with my Grand Cherokee 2006 as posted on post 39 by Tom (Cherokee, turn the CC on, hit set for the speed I want, engine kicks in like I floored it and keeps going. I have to turn it off to stop it or I would be up to 100 in no time. Can't set the speed, can't hit the DECEL button, wont do anything really, cuts the engine for one second then back to floored mode again. Fans and defrost are working fine.).

I took to a mechanic in my town and they diagnose that the problem is with the PCM but they don`t work with that and told me to take the car to a Jeep dealer. Anyone else had this problem?

Thank you in advance

Reply #50 michael (66.160.217.98) - Sun Aug 23 16:44:23 2009

1999 4.0 grand fan quit working where is the relay at???? is there a temp switch i kmow there is a sensor but what switches the fan to come on???

Reply #51 Maj (24.166.71.12) - Fri Aug 28 19:14:31 2009

Reply #2 fixed the issue. The hose is less than 6 inches andhas a curve to it. Mine was dry rotted and cracked at the curve point. It took me longer to get the battery and plate out than it did to replace the hose. I used a fuel line of the same diameter and NAPA just gave it to me for free since it was such a small peice.

Reply #52 Gerry (71.68.66.49) - Mon Sep 7 20:27:19 2009

Hi Pete#7

My 2002 Grand Cherokee has the same problem with the O/D.

The overdrive cuts off sometimes with no load and on a shalow climb at speeds over 50mph.

What I've noticed is that stopping the car, and re starting it, seems to reset something and the O/D engages again.

I've been told vaccum could be the problem...

If anyone can help, I'll appreciate it.

Great forum.

Reply #53 Cal (98.206.220.185) - Fri Sep 11 15:42:19 2009

I had the same problem as Jerry #2 above. I followed his directions and they were perfect. Cost me 60 cents for 6 inches of vacuum tubing at autozone. Took a few hours but then I am a novice. Now cruise control and all of the vent/feet settings work fine again.

Reply #54 Bob (70.245.73.29) - Sat Sep 12 16:14:59 2009

I have a 2004 Grand Cherokee cruise control light comes on, but it will not engage. All my vents work just fine. I replaced hose under battery tray, it was very slightly cracked at the neck but that was not the problem Still no cruise control. Any thoghts?

Reply #55 Scott (68.82.95.71) - Thu Oct 8 09:09:31 2009

Reply 23, help me. Had only defrost, no bottom or middle vents worked on wifes 2003 GC with 4.0. Checked on drivers side a 4" hose was off. Glad I kept ready posts. I was going to remove battery etc.

Reply #56 Peter (12.16.111.132) - Fri Oct 16 13:22:30 2009

I had the same lack of adjustment on my JGCL. Mine was caused when I replaced the fan relay. I cut into a compartment below(where the hose plugs in)doing the shortcut to fix the realy. When I found this forum I then saw what I did after seeing it wasn't the hose. I patched it with some epoxy and it works fine now.

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