2000 Dodge Ram heater/defroster air direction selector

Can you hear any clicking noise when changing the different air positions? It could be a bad mode door actuator let me know about the clicking noise and we will go from there.

I can hear no clicking.

Do have a manual ac or auto climate control?

it's manual. There's a knob you turn. Top knob is where the air goes (def, floor, to occupants, both, etc), middle knob is fan power, bottom knob is how hot or cold.

Looks like the positioning of the air outlet is ran by vacuum and has more then one vacuum actuator.Can you hear any hissing with the truck running if you put the air flow in different ways positions while listening under the dash?

Also the solid black vacuum line to the air flow positioning knob should have vacuum to it with the truck running.

I'll look/listen tomorrow. Is there a vacuum line going to the switch? Or where are they/it? Where do they come from under the hood. Maybe, if it's a lack of vacuum, I could follow the line/s and see if there's something worn, crimped, or broken.

And I'll look at this too, tomorrow.
Thanks,
Frank

You're welcome.

OK. I'm back. I listened and could hear nothing as far as air goes. I even took the dash apart and unscrewed the control box. Looking behind it everything appeared to be hooked up and like new. I switched from one position to another and noted that something changed slightly. It appeared to be the amount of air being forced through a channel - not vacuum but exhaust from the fan. As if it were being deflected in another direction. While less air appeared to come from the defroster vent, nothing came out of the front vents. Does this help with your diagnosis?

Can you tell me where the vacuum pump is on my diesel? If I know that I can check the hose to see if it has a break/leak/bend in it.

It sounds like the mode door is binding up that be in the center behind the dash see if that is moving smoothly.As far as a vacuum pump those are mainly used for power brake boosters.Do you have hydro boost for the power brakes or is it vacuum?

I have no idea.

where do you get to the door? from the inside, under the dash? Can I reach it without disassembling a lot?

You should be able to get to it under the dash inside there may be a plastic panel you may have to remove.I would try from the passenger side.Take a picture of your master cylinder and post it.

On the passenger side, under the dash, all is enclosed in a number of black plastic containers that don't have any indication on how to open them. I did see, however, one small flat, round item with wires coming from it that looked like it could be a controller of some kind. It appeared to be something that I could remove from its base.

I hope you get the pictures I have taken.

from another angle

first pic larger

Thats hydro boost meaning the power brakes a are powered by the power steering pump sending pressure to the power brake unit.No vacuum needed.

I have found another website while waiting for answers from you. In it it discusses a "blend door" problem that happens to Dodge trucks of my year. It also shows a fix. Would you tell me if this could be the problem and the solution. Please look at heatertreater.net and look at the 98-02 Dodge Ram. The video shows what I believe to be the piece under the dash on the heater component covers.

I have found another website while waiting for answers from you. In it it discusses a "blend door" problem that happens to Dodge trucks of my year. It also shows a fix. Would you tell me if this could be the problem and the solution. Please look at heatertreater.net and look at the 98-02 Dodge Ram. The video shows what I believe to be the piece under the dash on the heater component covers. (redid the reply so hopefully you can have a link).

It didn't redo. The link is heater treat.net

The blend door Controls the air temp from colder hotter etc are you having trouble with that also?Your mode door is vacuum controled from the knob not electronic.So do you have good vacuum to the control knob with the truck idling?Have you ever seen those vacuum hand pumps with a gauge you make a vacuum source to test vacuum actuators vacuum sources etc?

I'm not having trouble with the temp changing as I change the knob. I didn't understand that that was what the blend door did. When I unscrewed the controls (3 of them, the temp, the fan, the direction of air flow) I couldn't pull the controls far out. The wires won't allow much leeway. How do I check the vacuum? I have no tool to check it if I find it. Where is it? How do you unfasten it? Would I be able to determine if it's working correctly by just covering the hole and seeing if there is a vacuum?

posted a diagram of the vacuum plug on the mode/air flow postion knob connector.those are colored vacuum lines knob.the one that says resivour that would be the vacuum supply to the knob.if you just put your finger over it at idle that only tells you if you there s vacuum but not how strong it is,thats where that hand vacuum pump would come in plus you could use it to see if the vacuum actuators are holding vacuum.plus use it to move the mode door.I will get you a picture of the vacuum pump they may rent one at auto zone I know they sell them there.

Heres a picture of what it looks like some are made out of plastic.

I could barely see the diagram but I think I can find #3. I'll also see if I can find a vacuum tester. How do I unplug the line to test it? Does it just pull out? Do I have to take the entire unit off the switch and test it without disassembling the unit? I'm sorry if it appears I don't know much about what I'm doing, but I don't.

The vacuum connector should just pull off but make sure there isnt a little tab holding it on.Your probably going to have to unplug the electrical connectors To get the panel pulled out far enough to get to the vacuum plug.The electrical connectors have a tab that pushes aside sometimes there is a lock tab that needs to come out before the connector can be removed.

While waiting for a reply I looked up the vacuum diagram on line and found it in the truck. I noted that there was a one-way valve, with two rubber connectors attached on either end to tubes. The rubber had deteriorated and had breaks in it. I replaced them and, for a little, I had control of where the air came out in the truck. Then it stopped. I went to AutoZone and while they have that tool you talked about, it only produces suction. They didn't have anything to measure suction. I do have suction at the intake side of the one-way valve. I thought I should see if at the knob there is suction. I'll try to disconnect the unit with the 3 knobs so that I can isolate the suction line and determine if there's suction there. Does that sound correct?

That hand pump will measure and produce vacuum both the gauge on it will measure a vacuum source . sounds like your on the right track also make sure that one way check valve is good.

I'm sorry it took so long to reply. We had to go out of town. Today I went back to work. I used your information to proceed. I took the switch out of the dash, disconnected all the plug-ins, and then took the vacuum switch apart. Actually, I just separated the plugged in portion. I turned on the ignition and started the engine. There didn't appear to be any vacuum in any line, even the black one. Then I turned off the engine and followed all the black tubes and found one that went through the dash. I was going to unplug it, but then while seeing where to best take it apart at, I noted a break in the line. I taped it with electrician's tape, started the truck, and everything worked. So there was the problem. It's now solved. It took some time but it's done for no other cost than time and my donation to you. Thank you for all your help. You made a great difference in me solving this or not.
Frank

Your welcome glad to hear you found the problem those hoses rot out over time.we are hear to help tell all your friends thanks for using 2carpros.