Follow up HVAC issue

C

Commbubba19

New Member
Joined
Aug 7, 2018
Messages
17
Location
Omaha, NE
So my 02 TJ continues to trump me on HVAC problems.

After resolving the resistor issue and getting the fan to work, i still found that the directional controls failed to function. I checked the vacuum lines and all seems good and I cannot hear any leaks nor when spraying with soapy water do i see any bubbling or air movement being pulled in. I don't have an actual tester.

So i ordered and replaced the module that the vacuum lines connect to. In the process, the battery died. So after replacing the battery i was finally able to test to see if the control module fixed my issue. it did not. I also found that the actual knob itself is broken which would explain part of the problem (i've since ordered a replacement knob).

So in testing, some functionality does work.

Off = Off
Max A/C = Max A/C
Vent A/C = Vent A/C
Floor / Vent A/C = Floor / Vent A/C
Vent = Vent
Floor = Floor and Vent - This is where the problems start
Floor / Defrost = Floor / Defrost / Vent - Again air out the vent when it shouldn't
Defrost = Defrost / Vent - more Vent

So in all modes besides off, i always get air out the dash vents. Any thoughts on this?
 
Seems like the vent is stuck maybe? Is the linkage to shift the vent portion broken or disconnected?

Sent from my SM-G930V using Tapatalk
 
It's got to be either a vacuum line you aren't finding, or a stuck blend door. It really has to be, since that's how the air flow is controlled. I suppose the selector switch itself could be bad as well, but usually when that happens, none of the settings work.
 
? I have 97 ..if I stick my head under dash look up towards controls I can see the cylinders and actuators. I can then move controls and watch them move. Right now my center vent one the linkage is broken so it wont shift. Haven't had time to fix it

Sent from my SM-G930V using Tapatalk
 
Does this rig have AC and/or cruise control? If so mine did the same thing, there is a vacuum reservoir basically under the battery tray that has a line that goes into it. The line can be traced along the firewall and then down to the vacuum reservoir. Check that connection but note that the connection nipple on the tank is flush and difficult to feel/ find.


Sent from my iPhone using Tapatalk
 
MX952 said:
Does this rig have AC and/or cruise control? If so mine did the same thing, there is a vacuum reservoir basically under the battery tray that has a line that goes into it. The line can be traced along the firewall and then down to the vacuum reservoir. Check that connection but note that the connection nipple on the tank is flush and difficult to feel/ find.


Sent from my iPhone using Tapatalk
Click to expand...

X2 to this!
 
MX952 said:
Does this rig have AC and/or cruise control? If so mine did the same thing, there is a vacuum reservoir basically under the battery tray that has a line that goes into it. The line can be traced along the firewall and then down to the vacuum reservoir. Check that connection but note that the connection nipple on the tank is flush and difficult to feel/ find.


Sent from my iPhone using Tapatalk
Click to expand...

yes, i checked the line that goes to the 'box' under the tray and all 'looked' fine. it went up along the firewall and into a t fitting and to other various directions from there.
 
Have you inspected all the rubber fittings and tubes that connect to the intake manifold. Regardless of whether they go to the HVAC or not they are all part of maintaining proper vacuum. The rubber fittings at the manifold may look good but you have to run you hands on all the connections as the rubber will harden over time and fail.
 
TJ4Jim said:
Have you inspected all the rubber fittings and tubes that connect to the intake manifold. Regardless of whether they go to the HVAC or not they are all part of maintaining proper vacuum. The rubber fittings at the manifold may look good but you have to run you hands on all the connections as the rubber will harden over time and fail.
Click to expand...

well the t at the firewall goes to the manifold. so codes or other issues and it does change some hvac functions so it must be pulling some vacuum.

the only one i can't see is where it t's off and goes behind the glove box to the multicolored lines that go to the control module hvac knob.
 
Have you inspected all the rubber fittings and tubes that connect to the intake manifold. Regardless of wether they go to the HVAC or not they are all part of maintaining proper vacuum. The rubber fittings at the manifold may look good but you have to run you hands on all the connections as the rubber will harden over time and fail.
Commbubba19 said:
well the t at the firewall goes to the manifold. so codes or other issues and it does change some hvac functions so it must be pulling some vacuum.

the only one i can't see is where it t's off and goes behind the glove box to the multicolored lines that go to the control module hvac knob.
Click to expand...

You need to inspect all the hoses at the manifold. such as the hose to the brake booster.
 
Commbubba19 said:
yes, i checked the line that goes to the 'box' under the tray and all 'looked' fine. it went up along the firewall and into a t fitting and to other various directions from there.
Click to expand...

Did you physically unplug and inspect the vacuum box connection? Mine was also attached but the rubber was split just enough to not hold vacuum. I also recommend hooking into the box and with using a vacuum pump and gauge to see if it has pressure drop or just sucking in a hose to see if it holds. Cracked vacuum reservoir would not be uncommon.


Sent from my iPhone using Tapatalk
 
Top Bottom
Back