2nd Gen Non-Engine/Transmission HVAC Vent Trouble

[Sasquatch]

My Ram stopped blowing air out the "in your face" vents, and defaulted to the defrost and/or floor positions during last week's trip up 75 to Tennessee. It was about 15 degrees in the mountains, and the three day trip made me appreciate any heat I could salvage out the defroster. I've read that the defrost setting runs the A/C, too, which may explain why the truck didn't heat as well.



I checked for vacuum at the fittings behind the driver's side firewall in the engine compartment, and both seemed to be attached properly, and getting plenty of vacuum.



I can move the blower switch positions freely, and direct air to the floor or dash, but noplace else.



I also noticed, for the first time in its 100,000 mile history, that the truck's cruise control was "balky," and didn't want to stay where I set it. I tried performing the "retraining" (computer related) steps, and it seemed to do a little better, but the tendancy of the cruise, all of a sudden, is to want to drift upward in speed, then drift back down, and finally "hunt" its way to the setting I first selected. It's never done this before.



Curiously, once it finds the proper setting, I can hit the brakes, then hit "resume," and the truck will find and stay exactly at the correct speed without the drifting up/down problem.



I understand that cruise control "sketchiness" is often related to problems (vacuum-related) that also affect the heater vent controls, inside the cab. When I select the forward-blowing vent positions (as opposed to the defroster), I think I can hear the heat/defrost door actuator working, there's a change in defrost air pressure and sound, but no air comes out the vents. I don't think that the actuator pump which moves the heat/defrost door is the problem, but could be wrong.



I've checked all the vacuum lines that are visible along the engine compartment side of the firewall, and can't see anyting disconnected. I've also removed the three lines that I can see from their hard, plastic connectors and felt them to see if they are producing suction; the seem to be getting suction.



The one connection that was a little suspect was the line that enters the firewall behind the passenger side glovebox. This vacuum line has a plastic "L" shaped fitting, and the hose side that lead into the cabin seems very small and flimsy. I pulled it off, checked it, and was surprised to see how small the inside diameter of the hose was -- not much bigger than a "swizzle stick" you'd stir a drink with. The opening in the hose seemed to have moisture in it, but that could've been my imagination (and/or crappy eyesight).



I have not traced every vaccum hose back to its point of origin, and don't (for instance) know where the cruise control "servo" is located. Any thoughts anyone has would be much appreciated.



Thanks a lot.

 

[gitchesum]

Sounds like the acuator under the dash is bad. Mine is doing the same thing. It's under the dash, you can get to it from the drivers side.

Mine will hold in the dash vent position if I pull it down manually but it will not pull it down by itself.

 

[Sasquatch]

gitchesum:



Thanks for the reply, man.



Do you know what's involved in replacing the actuator? My mechanical experience has been limited to oil and fuel filter changes, and some other pretty basic stuff like installing Geno's gauges, mirrors, etc. I've pulled the dash bezel to install stuff and "T" tapped the cigarette lighter into new gauges, etc. , but would be worried about the prospect of very involved surgery that required a lot of equipment R&R.



What are your thoughts about the difficulty of this job, and did your cruise control begin acting up, too, at the same time your vent selection went south?

 

[illflem]

Most times problems like yours are caused by a vacuum leak. By far the most common location for the leak is the cruise actuator under the drivers side battery. Battery acid takes it's toll, sometimes rotting just the hose other times taking out the actuator.

 

[Cooker]

Replacing the actuator under the dash by the pedal is a very easy job. It might take you 1/2 hour if you stop for a couple coffee breaks

 

[Sasquatch]

Illflem/Cooker:



Thanks, guys.



I'll check the cruise actuator under battery, but don't think any damage would be "acid" related, 'cause I've had "red-tops" installed since '99, and keep the battery cases and terminals super clean.



I've got an exhaust brake, in addition to the regular air hose "plumbing," so there are plenty of hoses and fittings that could be suspect.



As relates to a possible problem with a door actuator, I'm confused about a couple of things.



First, the service manual refers to two actuators that control blower air direction doors. There is a "Recirculating Air Door," which controls whether the system gets air from outside the truck, or recirculates cab air. This actuator went out a couple of years ago, during a very hot Atlanta summer. I noticed its failure, immediately, because the force and coolness of the AC dropped, when I could no longer switch the door position to "recirculate. "



The dealer at first said it would be a fairly involved job, but the mechanic—who'd done this job many times before—managed to get to and replace the actuator without pulling the heater-A/C housing, which involves draining/recapturing the refrigerant, and other messy procedures. The dealer, Marietta Dodge, (a great one, by the way), charged me $125. 00 labor and materials. It was worth it to have the boosted cooling back on-line.



The mechanic gave me the defective actuator, and showed me where he'd removed it from under the glovebox area.



At least according to the service manual, the second actuator ("Panel-Defrost Door Actuator") is located in the same neck of the woods. Removal instructions also call for taking out the friggin' heater-A/C housing, which is, again, located under the passenger side (glove box).



I'm not sure which actuator is being referred to when y'all talk about an easily accessible and removable part which is located on the driver's side, near the accelerator pedal. . ?



I don't mean to be dense about this, but it'd be great if fixing the problem is as easy as you suggest it might be, but a few more specifics would be helpful, including (if possible) the part name, location (near pedal?!?), R&R tips, etc.



Thanks

 

[gitchesum]

You gotta love guys with a digital camera and time on thier hands.

I shot a few pictures of what went out on my truck. The actuator in the picture controls the dash vents. It's held on with 2 phillips head screws and it attaches to the vent door. It was kind of a pain to get it of the vent door when I removed it.

Everything vacuum related works on my truck. It would control from defrost vents to floor vents, it just wouldn't come out of the vents.

I have no idea what the proper name for the part is, nor do I have any part numbers because mine is still broken.



Hope the pics help a little.



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[Sasquatch]

gitchesum:



Excellent pictures, bro'.



I got down on the floor of the driver's side, craned my neck, and saw that puppy. Also turned on the engine, fired up the HVAC, and pulled down on the white, plastic lever. Sure enough, air came out the vents.



My question, though, is whether this vent "actuator," is really faulty, or whether the vacuum which causes it's circuit to be energized is at fault. See what I mean?



I think it's strange that the cruise control went south at exactly the same time my vents stopped blowing properly. The actuator in your pictures appears to be operated by an electircal circuit; there are no vacuum lines going to it. According to the '97 manual, the "Heater & A/C Control Panel (the panel with the Temperature, Fan-speed and Vent-Contol knobs) is entirely vacuum controlled. If you look at the back of that panel, there's a cluster of small hoses that make up behind the vent-selector knob in the "vacuum harness. " There's a different hose for each vent selector function; it's all vacuum controlled.



My question, then, is whether there is a vacuum-controlled solenoid which responds to the knob position on the control panel, and that, in turn, sends electrical current to the actuator depicted in your excellent photographs. If there's a problem with the vacuum system, then the vent-control-actuator's circuit is never energized, the arm doesn't retract, and the vents won't open.



I went out and looked around and under (to the extent I could) the driver's side battery to see if I could locate the cruise control servo (what the manual calls "speed control") but couldn't see much, so I'll haul the battery and tray out tomorrow, and take a closer look.



I really appreciate the trouble you went to in taking those pictures, buddy; it did help get me oriented. Thanks.

 

[gitchesum]

The actuator is completely vacuum controlled. The yellow tube going into the bottom of the acuator is a vacuum line.

I took the vacuum line off, started the truck and messed with the controls.

With the vents set at defrost, there is no vacuum coming from the tube, with the vent selector set at MAX A/C you can hear the air being sucked in to the tube, with the selector set at normal A/C, the vacuum increases.



You might see if you are pulling a vacuum at the tube. If not, it' might be in the controls or a vacuum problem.

 

[Sasquatch]

gitchesum:



Thanks for your patient help, friend.



I'm going to get the part from the dealer, tomorrow, and put her in, after checking for vacuum at the actuator.



I also discovered that there's nothing wrong with my cruise control. I have to "retrain" it, because I did too many "set" commands with my foot off the gas. That's according to the manual, a Homer-like thing to do.



DOH!

 

[Sasquatch]

gitchesum:



I swung by the dealership today, and bought the part. I think he said it was called a "Panel/Defrost door Actuator".



Anyway, it listed for $43. 26, and the dealer let me have it for $34. 61, 'cause I tried to look hungry.



Old part # - CH4720279

New part # - 4720279-AB ACTUATOR HE 24029001



Anyway, I printed out your picture, and showing it to him sped things up, considerably.



It took me a half hour to put it in, just as Cooker said it would, though it was awkward for this 52-year-old fat man to reach. Had to do it mostly by feel, and managed to chip off part of the little, plastic nipple that the metal actuator arm snaps over. I hope it stays put.



Anyway, problem solved, thanks to y'all, and this great resource.

 

[KEnhoffer]

I also broke part of the plastic nipple when I replaced the actuator. Eventually the actuator lever did come off the plastic arm. I solved the problem by holding it in place with a small chain quick link. I screwed the link between the actuator lever and the plastic arm. I has held fine.

 

[Sasquatch]

KEnhoffer:



"... I solved the problem by holding it in place with a small chain quick link. I screwed the link between the actuator lever and the plastic arm. I has held fine... . "



Hey, man,



Wish I could've sent you an email, rather than keeping this thread alive. I'm interested in the particulars of how you managed this repair. What's a "small chain link," and how'd you affix it. . ?



I tried to imagine a fix, too, but couldn't reach the attachment point where the nipple had broken with any kind of conventional drill. I wanted to leave the metal actuator arm in place, then drill the nipple with a small bit, and carefully follow up with a small diameter screw.



As you know, that area is very tough to get to, though, so I just figured I'd keep my fingers crossed and see what happened. Maybe a "Dremel" tool would work -- a drill bit mounted in a flexible, snake-like deal such as dentists use?



Thanks for your response.

 

[KEnhoffer]

Sasquatch,



A quick link, to my understanding, is made to join two pieces of chain together. I purchased mine from a hardware store. I got the smallest available, about less than 2 inches in length. It is a loop with one open side with a barrel that screws down to close the opening. I screwed down the barrel so as to pinch the actuator arm and nipple together. The open end of the barrel fit nicely over the remaining part of the nipple. The dealer had a replacement plastic arm, but I couldn't' determine how to replace it without breaking something else. This was much simpler. I too thought about the drill method, but like you dismissed the idea - not as flexible as I used to be.

 

[Sasquatch]

Ken:



Great description, buddy. I'll get one tomorrow; it sounds a little bit like a "C-Clamp. "



Thanks