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Dakker
Dodge Dakota
JOIN HERE
2/28/2002
17:04:45
|
 Subject: A/C and Heating Problems
IP: Logged
Message:
I really really really need help here.
My A/C and Heater work fine.. meaning the A/C is cold, the heater is hot. The fan works fine. My problem comes when i try to get the air to blow out the panel and bi-level. The defrost and floor settings work fine, but panel,bilevel won't work.
Here is what i know: The system works off a vacuum system in the 87 Dakota. After removing all other vacuum accessories, It switches immediately to all settings.
On the vacuum hose feeding the heating/cooling, there is a splitter. one 1/2 goes to the braking system... i obviously don't want to mess with that. the other half goes to heating cooling thing along with about 4 or 5 other vacuum powered accessories. ON each of the split lines there is what i believe to be a filter...
Since everything used to work, i'm guessing that the filter is stopped up just enough to keep the system from working. would anything be hurt if i just took off the filter.. I really don't think the filter can be replaced... But it might can be...
Or maybe just get a used filter? Help!
What do i do?
-Thanks!
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CW
GenIII
2/28/2002
19:38:45
|  RE: A/C and Heating Problems
IP: Logged
Message:
It is probably a check valve but it could be plugged.
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm throttle body, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat. Electric fan Convertion, HO cams installed.
Working on adjustable fuel pressure with return.
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Dakker
Dodge Dakota
JOIN HERE
2/28/2002
19:51:58
| RE: A/C and Heating Problems
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Message:
What is a check valve?
thanks!
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Dave Mitchell
Dodge Dakota
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2/28/2002
20:23:44
|  RE: A/C and Heating Problems
IP: Logged
Message:
A check valve will allow the air to be pulled out by the vacuum line, but if the vacuum goes away, dowes not allow it to bleed back into the line, thereby maintaining the vacuum.
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Dakker
Dodge Dakota
JOIN HERE
2/28/2002
20:56:41
|  RE: A/C and Heating Problems
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Message:
where is a check valve located? What does it look like? Can i change the part myself?
So a bad one can cause less vacuum pressure? it has some vacuum pressure... but just not enough!
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James
Dodge Dakota
JOIN HERE
2/28/2002
21:18:45
| RE: A/C and Heating Problems
IP: Logged
Message:
Another small possibility is something rolled around on your dash and fell down the derfroster vent, and is blocking the flaps that control air flow. Silly as that sounds, it happened to a 79 k-30 I owned. The defroster and the floor vents worked, but wouldn't let air out the dash vents. I took the unit apart when the heater core let go and found a couple rifle cartirdges from the previous owner.
It's another thing to check if the check valves are ok.
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Dakker
Dodge Dakota
JOIN HERE
3/01/2002
12:20:40
|  RE: A/C and Heating Problems
IP: Logged
Message:
I checked my owners manual and it said this:
Vacuum Operated Components
The following vacuum components should be changed:
Delay valves
Cacuum controlled orifice tank vapor valve
heated air temp sensor
Air cleaner vacuum motors <--- Vacuum motors???
Vacuum actuated electric switch
Hi-level purge check valve...
Ok call me stupid but i don't know about any of that... lol
I did find a check valve in an online parts store and it said this:
Air Compressor Intake Check Valve -- 1/2' Compression,1/2''
Is that what needs to be replaced? is it on the air compressor.. as in Air Conditioner compressor?
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CW
GenIII
3/01/2002
14:27:36
| RE: A/C and Heating Problems
IP: Logged
Message:
The thing you think is a filter is probably a check valve. Blow through it both ways and if it blocks one way it is a check valve. You could try a different source of vac on the manifold see if that works.
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm throttle body, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat. Electric fan Convertion, HO cams installed.
Working on adjustable fuel pressure with return.
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Dakker
Dodge Dakota
JOIN HERE
3/01/2002
15:25:41
| RE: A/C and Heating Problems
IP: Logged
Message:
Thanks CW! Assuming that is what's bad... do i have to have one of those? can i just take it out and splice the tube back together without it?
No parts store seems to have them. Maybe i can try a dealer?
Thanks.
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Sean
Dodge Dakota
JOIN HERE
3/01/2002
17:32:42
| RE: A/C and Heating Problems
IP: Logged
Message:
The little filter thing you see is called a vacuum switch. It allows vacuum to flow in one direction only. You can bypass it to test the HVAC system, but you'll want to put it back in the system when you are done testing. Under conditions of low manifold vacuum, the HVAC will behave erratically without it in there. The dealer will have one.
BTW: I've replaced one on my 2000 Dakota because, when towing on the highway, sometimes the air would stop blowing out the panel vents. It didn't change the problem, which I still have.
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Dakker
Dodge Dakota
JOIN HERE
3/02/2002
14:25:16
| RE: A/C and Heating Problems
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Message:
sean,
How much did it cost?
Thanks
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Dakker
Dodge Dakota
JOIN HERE
3/03/2002
12:51:05
| RE: A/C and Heating Problems
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Message:
I know the EGR valve works off a vacuum... could a faulty EGR cause a vacuum problem? My EGR needs replaced...
Thanks
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Dakker
Dodge Dakota
JOIN HERE
3/07/2002
23:48:05
| RE: A/C and Heating Problems
IP: Logged
Message:
you all were right.. it was a check valve!!!!
That little thing above totally disabled my heating and cooling system... Now it works like its new!!! It was nearly totally stopped up.. very little vacuum getting through...
Thank you all so much!
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Gus
Dodge Dakota
JOIN HERE
7/22/2002
11:06:09
| RE: A/C and Heating Problems
IP: Logged
Message:
I have the same problem on my '90 Dakota. Where is the check valve located?
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Dakker
Dodge Dakota
JOIN HERE
7/23/2002
11:57:52
| RE: A/C and Heating Problems
IP: Logged
Message:
On my old 87, it was under the hood... on the driver side firewall.... On mine, there are a few vacuum hoses running around... there are actually two of the valves.. one on the vacuum conctrolled stuff such as the heater/ac, and one on the brake line...
Hope this helps..
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Gus
Dodge Dakota
JOIN HERE
7/23/2002
12:07:10
| RE: A/C and Heating Problems
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Message:
Thanks Dakker, I found it and the problem has been fixed. The valve was OK but the the vacuum hose was broken.
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jbohio
Dodge Dakota
JOIN HERE
2/02/2003
21:17:23
| RE: A/C and Heating Problems
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Message:
I (97 dakota) have the problem as above.
defrost works fine, floor works fine, I've got heat and blower. But, I don't have any air coming out of the dash.
I've checked the check-valves under the hood (2 of them) and they are ok. I've removed the instrument panel cover, and the selector switch. I have vacuum at the input to the switch (nipple #3 - black hose). The vac actuator on the driver side moves when I change the selector switch. The vac actuator on the pass side does NOT seem to work. I've pulled vac lines to the pass side actuator, and sense no vac at any position of the selector switch.
What's the most likely to be wrong?
bad selector switch?
blocked / pinched vac hose? Although it is all the hoses on the pass actuator that don't have vac. I've only found 2 hoses to the pass actuator, but there must be 3, since there is 3 on the drivers side actuator and a total of 7 hoses at the selector switch.
Any help would be most appreciated... thanks
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jbohio
Dodge Dakota
JOIN HERE
5/13/2003
18:06:08
| RE: A/C and Heating Problems
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Message:
I continue to hunt for solution to problem described above. I have located 3 vac actuators. Each actuator has 2 hose connections. I've also located a vac-logic diagram for the control position. (i.e., when vac is applied to each actuator) What I need is a diagram of the heater/ac housing that ducts the air to the floor/panel/defrost, so that I can determine the proper position of flapper-doors for each of the control positions. Thanks for any help that anyone mitght provide.
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maxwedge1
Dodge Dakota
JOIN HERE
5/13/2003
20:39:06
| RE: A/C and Heating Problems
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Message:
I also have the same problem, no bi-level A/C or Heat - I have checked everything I can think of, my diagonosis is very similar to jbohio, have vacuum on driver's side but not on passenger's side, at least that effects operation of anything.
I have run into another guy the has the same problem - there must be someone on this site or passing through that has had this same problem and figured it out??????
We could really use your assist - any other ideas would be helpful - sweating my butt off here in Florida.
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jbohio
Dodge Dakota
JOIN HERE
5/18/2003
21:17:02
| RE: A/C and Heating Problems
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Message:
I have determined that the vac actuator on the pass side controls the recirculation duct. i.e., allows outside air normally to mix, but switches when max AC for inside recirulation. Knowing that much, I've determined that the vac actuator closest to the drivers door side is the actuator that controls the air to the panel ducts. (and ofcourse that is the hardest one to get to) I suspect that the flapper door has become detatached from the actuator or the the lever to the duct is broken. I have confirmed that the acutator is responding to the control switch, but now I'm stumped as to the best way to determine if the actuator arm is detached or the duct door - lever is broke, or whatever. Do I have to dismantle the entire dashboard? Yikes!
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David
Dodge Dakota
JOIN HERE
8/12/2003
10:47:53
| RE: A/C and Heating Problems
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Message:
I'm trying to find the vacuum check valves on a 92 Dak 3.9L that is having the problem - it blows cold but does not come through the front/bi-level vents, only the defroster. Can you help me find these things?
So far I've found a vacuum device of some kind that is on the EGR, and a device that looks like a vacuum distribution point with a lot of hoses going in and out, on the drivers side of the engine, next to the throttle body.
No check valves that I can find so far. Please help!
thanks
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