1996 Dodge Grand Caravan LE AC/Heater Blower, Relay and Resistor Block Problems 101

[zachr101]

Originally Posted by bolognaman

I was just curious if anyone had more info for a 97 caravan. My issue is that the blower will work fine when it is cooler weather, but after it sits in the sun for awhile the blower won't come on at all. The fuse is still good, I couldn't see anything wrong with the relay (located in the power distribution center under the hood) but how can you tell with a 1 x 1 black box, and I couldn't find anything wrong with wiring behind the glove box. I'm open to suggestions, just trying to avoid multiple trips to the parts store. The material in this post has been helpful.

You can slide off the black plastic cover off the relay and see inside contacts to verify wheather or not they are burned. If stripped relay is plugged in the socket, you may push manualy the contacts together. The simplest way to verify the relay is to shuffle these relays and exchange it for some of the others (they are identical) and to see, if it will work in different location.

[HeadlessHorseman]

Originally Posted by zachr101

You can slide off the black plastic cover off the relay and see inside contacts to verify wheather or not they are burned. If stripped relay is plugged in the socket, you may push manualy the contacts together. The simplest way to verify the relay is to shuffle these relays and exchange it for some of the others (they are identical) and to see, if it will work in different location.

If this is the first time you have had a problem with your '97, chances are excellent that a relay replacement is necessary. It's a cheap and easy test to buy a new relay and install it, but remember that a good relay can make a marginal motor seem fine in the short term. I have found that relays and motors are best replaced in pairs. A marginal motor can draw more power than usual and cause contacts of a new relay to burn and pit at a far faster rate than normal.

[Stevo2]

Just trying to help if I can. If the 40 amp fuse is a Maxi-fuse than it is available from these places also.
NAPA-BK 7821079
Kragen, Checker, Shucks, Rockauto-MAX40
Mopar-6101641

[HeadlessHorseman]

Thanks for the pic of the fuse and source info, Stevo2... I'll work it into the original post. This is great... it just keeps getting better and better... thanks for contributing!

[91cabernetcaravan]

Ahhhhhhh!

Am I glad I found this forum and this thread. I too have a AC/heater system problem, but I have seen no one mention this one before. Or if they have I completely missed it I am no mechanic, and am not even really much of a weekend mechanic, but some things I can do myself. Example: I switched out the entire speaker system on my Caravan in one afternoon. Also, I replace my own burned out headlamps and marker lamps. That stuff... piece of cake.
But this one frosts my cookies.....
Dear HeadlessHorseman:
I own a 1991 Dodge Caravan (cabernet in color, I love the old beast).
As I drive merrily up the highway, the fan, which runs fine at all speeds blows fine, but the damn air doesn't come out. I accelerate, I hear a flapper inside the dash start vibrating and slam shut shutting off the air flow into the car. I let off on the gas (or top a hill and drop into cruise mode) I hear the flapper open again. Now, I know for a fact it didn't act this way before.
Everything else regarding the AC/heater system seems to work fine, for a car that is at the advanced age of 206K miles. Now, I read through this forum but I have seen no comment regarding my second generation Caravan (model year 1991). I'm fairly certain I can do the dash access myself, but what's causing this flapper to vibrate closed when I speed up and then pop back opened when I let off? This is a damned nuisance when it's hot or cold, and I need air blowing in a regular fashion.
Any thoughts?
Neil in Tujunga

[HeadlessHorseman]

Originally Posted by 91cabernetcaravan

Ahhhhhhh! ...Dear HeadlessHorseman:
I own a 1991 Dodge Caravan (cabernet in color, I love the old beast).
As I drive merrily up the highway, the fan, which runs fine at all speeds blows fine, but the damn air doesn't come out. I accelerate, I hear a flapper inside the dash start vibrating and slam shut shutting off the air flow into the car. I let off on the gas (or top a hill and drop into cruise mode) I hear the flapper open again. Now, I know for a fact it didn't act this way before.
Everything else regarding the AC/heater system seems to work fine, for a car that is at the advanced age of 206K miles. Now, I read through this forum but I have seen no comment regarding my second generation Caravan (model year 1991). I'm fairly certain I can do the dash access myself, but what's causing this flapper to vibrate closed when I speed up and then pop back opened when I let off? This is a damned nuisance when it's hot or cold, and I need air blowing in a regular fashion. Any thoughts? Neil in Tujunga

I think RIP is right... it sounds like a vacuum issue. My experience with leaking vacuum lines has been that they fail mostly at connection points... usually the leaks happen where lines are connected, like rubber connectors... in some cases, the lines themselves leak, but only after they have been rubbing against something for a while and worn thin, pinched or heated and melted when they touch something hot.

Whatever it is, you need to get a schematic of your entire heating system which includes lines, acuator(s), manual and thermal switches, electrical circuits... everything. You'll also have to take a look at your blend doors and make sure linkages are connected and hinges are OK. You may have to take your dashboard apart to do this right. I don't know what you might find in a Haynes or Chilton's manual, but it might be a good idea to get both of these manuals if you plan to keep your '91 for any length of time.

I would plan to spend an entire weekend running down this problem... maybe a 3-day weekend... and don't plan on using this vehicle during that time because it will be in pieces. Best of luck!

[91cabernetcaravan]

Thank you for the quick responses on this.
Okay, well... I have a terrific mechanic that has been servicing my car and knows it inside and out. It sounds like a job for his skills, but the info is valuable.
I do have the service manual, which has helped me tremendously in doing the more simplistic stuff, but this seems like it may be a few hairs out of my league.
I'll be reading up on that tonight and see if I can learn anything else. If time and finances permit, I'll look into getting a Haynes or Chilton book.
I'll report back if I learn anything new. May be a few weeks, but I'll have this thread bookmarked to add to the information base.
Again, thanks for the insight.
Neil

[91cabernetcaravan]

Hm. Okay. I have my Chrysler service manual in front of me for this evening's reading entertainment. Section (or chapter) 24, the fun stuff begins at page 31. I did notice something curious while playing with the termperature slider and popping the directional air buttons. One time it popped the funky flapper opened with a corresponding "pop" on the car stereo.
Well, at 206K miles, I guess another strange sound isn't all that unusual. I'm going to wade through this material for an evening and see if I can glean anything else.
Neil in Tujunga

[Stevo2]

Originally Posted by 91cabernetcaravan

Thank you for the quick responses on this.
Okay, well... I have a terrific mechanic that has been servicing my car and knows it inside and out. It sounds like a job for his skills, but the info is valuable.
I do have the service manual, which has helped me tremendously in doing the more simplistic stuff, but this seems like it may be a few hairs out of my league.
I'll be reading up on that tonight and see if I can learn anything else. If time and finances permit, I'll look into getting a Haynes or Chilton book.
I'll report back if I learn anything new. May be a few weeks, but I'll have this thread bookmarked to add to the information base.
Again, thanks for the insight.
Neil

Neil, when you hear this door shut and the air stops coming from the vents, is it going up to the defrosters instead?
Check the vacuum supply line where it attaches to the engine for a possible bad rubber connector, also there is probably a check valve in that line also that allows vacuum to flow to the interior but is supposed to stop it from going back to the engine during deceleration or high engine load. Could be the pushbutton asm is leaking or the vacuum hose harness that connects to it. The best thing for checking these vacuum circuits is a MityVac, you can see vacuum readings, operate the doors and check lines for leaks.
www.mityvac.com

[91cabernetcaravan]

Thanks, SteveO for the followup.
Well, I read the service manual, but my own personal tool and skill set isn't qualified to do this kind of work. Conclusion, I will defer to my machanic, who will probably sub it out to another shop, I expect. Not sure he does that kind of stuff on site.

"Neil, when you hear this door shut and the air stops coming from the vents, is it going up to the defrosters instead?"

Not sure. There is a obvious audible sound change when that happens, and yes, it does sound like that, but I do not know it in fact. If that's the case, what is the probable situation?

"Check the vacuum supply line where it attaches to the engine for a possible bad rubber connector, also there is probably a check valve in that line also that allows vacuum to flow to the interior but is supposed to stop it from going back to the engine during deceleration or high engine load. Could be the pushbutton asm is leaking or the vacuum hose harness that connects to it."

I can check it, perhaps make minor adjustments with the tools I have at hand. Beyond that, I have to defer to an expert..

"The best thing for checking these vacuum circuits is a MityVac, you can see vacuum readings, operate the doors and check lines for leaks.
www.mityvac.com"

Well, given the current weather situation (our mild southern California climate is thankfully holding true for the time being) this is hardly a major issue on my car. Other mechanical things that need addressing have higher priority currently: ie. I'm buring a quart of oil a month these days; my automatic transmission is a rebuild and at low speeds I have to downshift into 2nd gear due to excessive vibration; almost all of my dashboard illumination is burned out making it very hard to see my instrument cluster at night (fun, fun); add to that a handfull of annoying minor issues, like one license plate light fused -- as I said, old car...
Anyway, thanks all of you for the help and information. At the very least I can sound somewhat literate when I discuss this with my mechanic.
I'll have this problem addressed on one of my rare days off in the near future. I'll report back then.
Thanks, guys!
Neil in Tujunga

[91cabernetcaravan]

IN RESPONSE TO STEVEO2:

"Neil, when you hear this door shut and the air stops coming from the vents, is it going up to the defrosters instead?'"

The answer is YES! I drove to work yesterday afternoon with the fan on just to listen to the noise it made. I also ran my hand over the different outlets, and you hit it on the button. The "flapper" slams closed upon acellerating and the air flow shifts to the defront outlets, even though the button is set on "FLOOR".
Oddly, shifting the button positions didn't change it; the flapper actuated on increasing motor strain, and reopened -- sometimes -- when it dropped back to an even cruise speed.
The night's trip home -- it was fairly cool -- it took a long time before enough heat poured out of the defrost outlets to warm my feet -- which was my intention at the time, again, the button was on "FLOOR".
I'm getting a niggle here that maybe one -- or both -- actuators need replacing?
I say 'maybe' because, when defrosting (rare here but sometimes it's needed) if one of those acutators is for defrosting, I'd say it works fine.
Anyway, just one brief update. I'll keep an eye -- and hand -- on it and let everyone know if I learn anything else.
(Again) Neil in Tujunga

[Stevo2]

Originally Posted by 91cabernetcaravan

IN RESPONSE TO STEVEO2:

"Neil, when you hear this door shut and the air stops coming from the vents, is it going up to the defrosters instead?'"

The answer is YES! I drove to work yesterday afternoon with the fan on just to listen to the noise it made. I also ran my hand over the different outlets, and you hit it on the button. The "flapper" slams closed upon acellerating and the air flow shifts to the defront outlets, even though the button is set on "FLOOR".
Oddly, shifting the button positions didn't change it; the flapper actuated on increasing motor strain, and reopened -- sometimes -- when it dropped back to an even cruise speed.
The night's trip home -- it was fairly cool -- it took a long time before enough heat poured out of the defrost outlets to warm my feet -- which was my intention at the time, again, the button was on "FLOOR".
I'm getting a niggle here that maybe one -- or both -- actuators need replacing?
I say 'maybe' because, when defrosting (rare here but sometimes it's needed) if one of those acutators is for defrosting, I'd say it works fine.
Anyway, just one brief update. I'll keep an eye -- and hand -- on it and let everyone know if I learn anything else.
(Again) Neil in Tujunga

Neil, you have a vacuum issue. I doubt that it is the actuator itself as they very rarely go bad. The deal with the "Defrost" is a safety feature, if the Heat-A/C has a vacuum leak the door acuator is designed to "default" to defrost so that you can see where the heck you are going.
Your problem could be in a number of areas in the system such as bad parts or hoses,etc. You might feel more comfortable having your mechanic look at it? You could try getting a used dash control asm and replace that and see what happens. I'm sure you will make the decision that suits you best. For a used part you can try here www.car-part.com and search under "Heater/AC Control".

[91cabernetcaravan]

WHoa! Great. Thanks, Stevo2!
Very interesting. This safety feature is nowhere mentioned in the manuals I have. Okay, I have enough to move forward now.
As I mentioned before, I'm not much of a weekend mechanic compared to you guys, but I will make an attempt to trace down issue as best I can in my garage. If I find out anything of interest, I'll drop in here again.

You know, this is fun. A good practical learning experience, if nothing else.
Thanks for being here, guys, and thanks for the feedback. I will follow up.

Neil in Tujunga

[Boother]

Thanks for the great info in this post. I just replaced my blower motor on my 97 with your help.

One thing I would like to note, there is no need to go through the big ordeal of hacksawing and using a puller on the cage. I simply took the clip off, sprayed some liquid wrench in the shaft and had a helper hold a screw driver on my bench and pushed the cage off. The screw driver was used to push in the shaft/motor while I applied force to the cage.

[HeadlessHorseman]

Thanks for posting the results of your efforts Boother. Good to hear it worked out well for you. I just assumed because getting the fan cage off my old motor was a biotch, it would be a biotch for everyone else. Thanks for letting us know that there may be an easier way to get the fan cage off for some folks. Cheers! P.S... I added your note to the original post.