Vacuum diagram/schematic for 2002 Caravan climate control

First of all you haven't stated what you are looking for exactly. Are you hearing a hissing noise and want to locate it? Is there a problem with the opperation of the AC/Heater control? Is the engine running rough and you suspect a vacuum leak?

If the first is the case you can start by pinching off the vacuum line that feeds 1) the heater controls from the engine compartment and see if the hissing goes away and 2) by doing the same with the brake power booster vac line (this assumes it has a vacuum power booster as aposed to a hydroboost unit).

If that's not it then you probably do need a vacuum diagram. Most of the major auto repair manuals have something but they may not be accurate due to changes during the year and the dealer is going to have to be relied upon.

That hissing could be a snake under the dash also.

Thanks Bob,

My books are all way to old. My last couple of gigs were at dealerships and that ended in 93. If I need something now I go to the library or pick someone else's brain, like yours for instance.

You could be right about that snake though.

(Shhh. My book was from 89. And for full sized vans at that. That's why I suggested he compare colors first. But why would Chrysler change the function of a color code?)

The only information on the vacuum hoses for Chryslers I have is a few years older than yours. But it's the only help I can give you. The good news is that as a company, they should stick to the same plan.

• #1 on the dash control is green, and goes to the hot water shut off valve (in the heater hose), and the vacuum motor that allows fresh air, or recirculating air to enter the HVAC system.
• #2 on dash control is red, and goes to the vacuum motor that chooses between hot air, and cool air. It blends the air flow to achieve the correct temp.
• #3 is the hose that goes out to the engine to provide vacuum (as a power supply) to the controls and air motors.
• #4 is unused on my diagram.
• #5 is brown, and goes to the same vacuum motor as the red #2, but on the opposite side of the motor.
• #6 is yellow and goes to the vacuum motor that chooses weather the air comes out the heater duct, or the defroster ducts.
• #7 is light green, and goes to the opposite side of the vacuum motor that has the dark green #2 hose on it. It balances between outside air or recirculated air.

This is as close as I can get you right now. I hope it helps. Follow a few hoses to be sure they are still using the same color code. I doubt very much anyone ever rerouted these hoses. If the hose is attached to the location, it is almost always the correct location. If this is not correct for your car, let me know, and I will dig deeper. Good luck.

Thanks, Bob and Shadetree.

Shadetree, I'll give your suggestions a try. Very good idea.

Bob, if Shadetree's suggestions indicate that the vacuum leak is in the van's cabin, I'll most certainly rely on your breakdown.

Shadetree asked for more info so if it's useful, here goes. The climate control used to work great. Last night I worked out a timeline of activity on the van and realized that 2 things happened between the time the HVAC worked perfectly until now. 1) I had the tranny serviced, and 2) I replaced the spark plugs and cabin air filter.

This is specifically what's happening: when the climate control is turned on, there's an immediate hissing sound like a vacuum leak. When the control is turned to direct air through the various ducts, more vacuum leak is heard along with the sound of doors opening and closing. The vacuum leak is now almost constant whereas before it would occur, then pause, then recur.

The heat still continues to work but the AC doesn't put out cold air. A mechanic said the AC compressor is properly engaging and he suspects a vacuum leak of some kind also.

Does this help in any way?

Thanks again for your suggestions.

If no position on the dash control causes the vacuum noise to stop, it should be one of three things. 1) the hose leading to the dash is leaking. 2) the dash control itself is leaking. 3) one of the dual vacuum motors is leaking across the motor and you here the vacuum escaping from the control. You are going to have to get your head into that dash to isolate now. Good luck.

Curiosity got the better of me so I went out to test the controls.

When the air is directed toward the passengers' feet or when it comes out of the dash, there doesn't appear to be any vacuum leak sound. When the air is directed to defrost or when the AC is on, the vacuum leak sounds.

Would that make sense??

What does sense have to do with anything? Let me get to my diagram again and i will post again in an hour. Till then try to avoid the snake.

Try disconnecting the light green hose. ???????????????

A vacuum hose will slip off its barb because it has lost elasticity due to age, heat, and ozone. If you have enough slack, cutting a half-inch or so off the end of the hose will sometimes allow you to restore function, at least temporarily.

The stethoscope is an excellent suggestion. Discovering the exact origin of any sound is tricky, as anyone who has ever tried to locate a chirping cricket can attest.

I am in complete sympathy with your problem. Many years ago I rebuilt the climate control of a 1973 Chrysler New Yorker using switches and solenoid valves after the vacuum-actuated one self-destructed.

I am old enough to remember vacuum motors on windshield wipers. They didn't work very well, either.

Good luck!

They didn't work very well, either.

Yea, they sucked.

I will bet on #2. Assuming that you have a V-6 engine, you have to take off a whole lot of garbage to get to the back bank of spark plugs. If a vacuum hose got misconnected (or improperly reconnected) in reassembly, this might be the culprit.

I looked in Chiltons '96 - '02 repair manual, to no avail. The damn thing is worthless.

We happen to have a '96 Caravan.

Bill

The 2002 Caravan ventilation doors are controlled by 12 volt dc motors. These actuators replace the old vacuum servos.

There is a bulletin concerning a hiss noise from the evaporator case though. The fix involves installing a "evaporator inlet flow straightener", which is basically a plastic insert in the inlet side of the freon line. If that doesn't fix the noise, there is a rubber insert that goes inbetween the inlet and outlet pipe.

The time allowance for the entire procedure if all steps are needed is 4.5 hours. If you want to tackle it, I can send you a copy of the entire bulletin.

My hunch is that snake won't eat much!

"When the air is directed to defrost or when the AC is on, the vacuum leak sounds."

This previous information, combined with your knowledge of the service bulletin, gives some clear pictures to us. You surely deserve a GA for this new info.

As a test, He could simply set the scenario till he gets the hissing. Then cut the power to the compressor clutch. If the noise stops BINGO.

Did the factory offer to pay for the repair? But most importantly How accurate was my color code? ( The only color code I could find for Chrysler was from a 1980 full sized van service manual.)

The bulletin came out in 2003, so it would have been covered, ah, then.

Your colour codes were highly accurate. Except they didn't change the colours, they changed the function from hose to wire. All your colours are on the wires! Good job!!!

I waited for a while, and no one was having any luck finding a code for 2002. I knew I had an old factory manual. The only question was if Chrysler had changed it in 22 years.

The change to electric motors does not surprise me. We first saw the trend with Chrysler, when they went to the gear reduction starter. Since then, we have seen smaller and smaller electric motors used for lots of things. Power door locks used to be solenoids, now they are motors. Starters are all smaller high speed designs with gear reducers to bring the torque up to the needed amount. Now HVAC doors. Small electric motors must be very cheap to make indeed.

Thanks for the excellent post, Autotechnocracy!

I would greatly appreciate a full copy of the bulletin if you could forward it.

Thanks again!

I will gladly do so if you email me an address as I can't seem to get it to copy here. autotechnocracy@sbcglobal.net

Diagrams and brainstorming don't get the ruptured hose fixed. Let's put a little K.I.S.S. principle into it. Three feet of vacuum hose with one end taped to a stick/screw driver, your choice. Poke around under the dash or where ever you suspect the leak while holding the other end of the hose to your ear. When you locate the leak, fix it. Job done.

When you locate the leak, fix it. Job done.

Or when the snake bites the stick, drag it out of the car.

Hello.

I am the owner of a 2000 Dodge Caravan. I had a similar hissing noise that began after a tune up. The A/C compressor failed shortly after and I had it changed. The hissing went a way and then came back. I couldn't find out why. Later we discovered the evaporator coil had a leak. Although I didn't have the opportunity to inspect it myself, I suspect that it was a small crack in the evaporator feed tube. It sounds like you've ruled out the AC as a source of problem. However, I thought you might find this information useful in the event that you can't find a vacuum leak, that it you might be worth checking the refrigerant pressures; as I discovered the hard way.

Here's another laugh: in repairing the evaporator, somehow the mechanic at the dealership managed to do something to the speakers. I'm almost afraid to bring it back!

Best wishes.

Greg

Thanks for your post. Very interesting.

I definitely haven't ruled out the AC as a problem though. On the weekend I tried to track down some vacuum lines that entered the climate control box (behind the glove compartment in front of the passenger seat) but couldn't find any. I found the small motors that have been mentioned in other posts and lots of wiring connections so I started to wonder where the heck a vacuum sound could be coming from.

I did narrow the noise down to a specific area but couldn't get to it easily because of some very-difficult-to-get-to screws. At the end of the day I took a step back and reconsidered the fact that I still don't have AC, which was the original problem.

I wonder if the trouble you had is really what I'm experiencing also.

Questions for you: did you hear the hissing sound when you selected the defrost setting? How much did it cost to get the evaporator feed tube fixed?

Thanks again for the post!

Try Chilton manuals for your Caravan. You can find them at any Auto parts store or on Amazon.

http://chilton.cengage.com/

Here are a couple more on-line car manual sites:

http://www.repairmanual.com/

http://www.eautorepair.net/

Just wanted to say thanks again for all the advise and suggestions.

Autotechnocracy provided the complete service bulletin but after reading it I realized I'm nowhere close to having the tools necessary for the repair (but it would be cool to have them!).

I resorted to going to my local dealership who immediately diagnosed the problem as a low refrigerant level. They topped it up, added some dye to the R134a and sent me on my way with a request to come back in a few weeks so they could use an ultra violet light to see if there are any leaks (revealed by the dye being sprayed onto a surface close to an AC part).

Interestingly, I asked why the hissing sound would be heard if the AC was off but the defrost setting was chosen. They said the defrost actually uses the AC system to help dry the air.

Thanks again everyone!

Hello.

Sorrry for the delay in responding. I have been involved in activities that have kept me away from the computer. It did hiss when I put on the defroster. It cost about $600 to have the evaporator replaced. I'd also suggest that you take the temperature differential of the system ASAP after it is corrected. By watching this temp, you can have a quick and easy double check. As the refrigerant leaks you should initally see the temp differential get larger until you get to the frost point.

Best wishes.