[bakpakr]

Ok after owning and driving my Jeep for a few weeks now I have a couple questions.

1. My HVAC system when I turn the engine off I can hear what sounds like the doors moving. I have not really investigated but like I said it sounds like the doors are moving inside the enclosure. Is this normal or do I need to investigate further?

Also I ran the diagnostics on the HVAC system. At least I hope I did it correctly. I pressed both the ac and recirc buttons together then turned the left knob one click. I got an error code that if I remember right was for my blend doors. But I get both cold and heated air out of both sides. But while I turn the left knob I can get a bunch of numbers and they are sequential. 1,2,3,4... so on and so forth. I really really need to get a manual.

2. When I first start out and I turn the wheel sharply I get a rumble in the front end. but after I am driving for a while I get no rumble. It only happens when I am going slow and the vehicle is cold. Like I said after I have driven for a short period of time it does not do it. Any Ideas? I have yet to get the front end off the ground to check suspension components for wear. Also I see no evidence of tire rub. The tires are the stock size and the suspension is stock.

I am sure there will be many more questions.

Now for some background on me. So you can see you are not talking to a total bone head hehe. I have over 30 years experience as an automotive mechanic. I have worked on about every type of wheeled vehicle built. But my experience with Jeep products is VERY limited. I can count on my one hand the number of Jeeps other than military M151 Jeeps I have worked on.

I really really need a few days where I can jack my Jeep up and go over it with a fine tooth comb and also get me a good manual.

 

[Frango100]

Welcome to the garage.
Don't worry about the noise of the actuators in the HVAC housing, that is normal. More or less one minute after switching off the ignition the doors will move to a preset position.
I would also not worry about HVAC fault codes when the system is working fine. They can be history faults which where never reset. Just disconnect the battery to errase all. But even if the faults come back, i would not worry as long it heats and cools.
The sequential numbers are the so called pointer numbers. You can select an component when you have the list of numbers and then you can see on the other display the actual position and with the right temp knob you can manually move doors.
For the second item, is your jeep quadra drive? Could have to do with a too low limited slip additive percentage. Over time the additive looses its function and you get tire rub on the ground when making tight turns because the vari loc locks completely.

 

[bakpakr]

Frango excellent info thanks. Also thanks for the welcome.

As for the door movement that was the direction I was leaning toward, that type of scenario but was not sure. It just had me a bit worried with all the info I see with the blend doors being a weak point in the system.

Also to the diagnostics this just goes to reinforce my need for a manual. Looks like I have to run out and get myself a Chiltons.

Yes I do have the Quadra Drive system. Looks like I will be changing out the transfercase fluid asap.

Again thanks for the great info.

 

[Frango100]

Quadra drive has a vari lok in each differential. For that reason you need to add the limited slip additive to both differentials or buy the fluid with the additive already mixed in it. The diffs take 75W140 synthetic and when i'm not wrong 4 oz of additive each.
The T case (NV247) needs special Mopar fluid, which is Mobil 424, but no additives.
Regarding a manual, i use the original jeep service manual. You can find it online for free, just google it. Take care to get the manual for your build year, since there can be some small but significant differences between the years.

 

[p3vinny]

bakpakr

Welcome! Frank is right on with his advice. The blend door movement after shutdown is normal. If the codes you are getting refer to the blend doors they should be in the range of 45-57, and there are many posts about 52, 54, 56 which refer to recirc, left and right door travel too large. Those are usually indicative of blend door failure since the motor keeps travelling beyond the plastic tab "stop" of the door in question.

When you are in the diagnostic mode you can clear the historical faults by pressing either ac or recirc button and holding for 3 sec. If your codes are in the above range they are historical. If they are in the 20s then they are currently observed faults and cannot be cleared.

I also have an '04 Limited. I would check the front differential first. It needs 2.5 pts of 75W140 fully synthetic gear oil plus 2.5 oz of Limited Slip additive. I used Mobil 1 and K&W Positraction. The rear takes 4.75 pts and 4 oz. The Transfer Case requires use of special fluid, and I've only used the Mopar fluid from the dealer.

Finally, you can get a Factory Service Manual online from eBay for around $100, plus there is an electronic version around as well if you search. There are differences (sometimes significant) between model years so make sure to get the correct manual - I used to have a 2000 WJ and I still have the manual - it would be difficult to try and use it to work on the 2004.

I geek out for my cars and keep a pretty detailed spreadsheet - I attached some info for you of general specifications and service plan that I screen captured off my spreadsheet. If you would like I can email you a copy the spreadsheet, but I don't think Excel files can be uploaded to the forum.

Hope some of this helps!

Phil

 

[p3vinny]

bakpakr,

Frank pointed out 2 errors in the spec sheet I included earlier - The engine is 16 valve not 32 valve, and also the rear brakes are solid disc vice ventilated. Ironically, that is not what I meant to post - what I originally meant to include is a capacity / spec sheet that I compiled for a more 'handy' quick reference.

Don't know how to delete the original file, but it's not really too useful anyway. Hope this helps, and if not just file it in the appropriate place

Phil

 

[Frango100]

bakpakr,

Frank pointed out 2 errors in the spec sheet I included earlier - The engine is 16 valve not 32 valve, and also the rear brakes are solid disc vice ventilated. Ironically, that is not what I meant to post - what I originally meant to include is a capacity / spec sheet that I compiled for a more 'handy' quick reference.

Don't know how to delete the original file, but it's not really too useful anyway. Hope this helps, and if not just file it in the appropriate place

Phil

That is a handy list Phil. For you guys in the USA its probably no big deal to buy the "special" Mopar T-case fluid, but for me its very expensive from the stealer. Some research learned however that the special Mopar T-case fluid is made by Mobil under number 424. (its in fact a fluid made for tractor transmissions, at least its for something ofroad:lol
My jeep service manual (2004) shows the same amount of limited slip additive for the front diff as for the aft diff, which is strange since they have different volumes. Which manual do you use?

 

[p3vinny]

Frank,

I use the Factory Service Manual. As for the limited slip additive It looks like it is just a ratio... i.e. roughly 1 oz per pint. My manual says add 2.5 oz per axle. I think it is a typo though. The manual for my 2000 said to add 4.0 oz to the D44 and 2.5 oz to the D30. IIRC WJJeeps.com - Jeep Grand Cherokee WJ 1999-2004 also has the same info.

I have read that others have used aftermarket alternatives as you suggest for the transfer case fluid, but interesting enough they are more difficult in my area to come by, and also are not much cheaper.

Phil

 

[p3vinny]

I use the factory service manual - mine also says the same for both (i.e. 2.5 oz for both the D44 and D30). I think it is a typo, though. My 2000 FSM said 4oz and 2.5oz, which makes more sense. I think WJJeeps.com - Jeep Grand Cherokee WJ 1999-2004 also has the same info. Does your FSM say 4.0 oz each?

As for the transfer case fluid, the Mobil 1 fluid is hard to come by here - easier to just get from the dealer... it is ridiculously expensive though.

Phil

 

[bakpakr]

When I stopped in to the dealer to pick up some door panel clips I asked about diff service. I was quoted $255 for both front and rear diff's and the transfer case service.

I will more than likely do it myself but that does not sound all that bad price wise.

 

[p3vinny]

$255 Sounds very reasonable for both differentials and the transfer case. The fluids alone will cost you ~ $100.