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Unread 01-12-2014, 07:59 PM   #1
colton_xj
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Heater Vent Problem, But Cruise Works

I apologize if this has been covered, but my searches turned up dry.

I have a 1999 Jeep XJ Sport, automatic, mostly stock. My heater isn't working, and I've ruled out the heater core, blend door, and blower motor, which, from what I've read, suggests a vacuum problem. Trouble is that the cruise works fine, and the vent selector hasn't defaulted to defrost. The air seems to vaguely come out of all the vents at one time, but there's not much flow, almost like there's something blocking the ductwork and only allowing a little bit of air to come out.

Any suggestions or links to places where this has been addressed would be very helpful. Thanks!


Last edited by colton_xj; 01-12-2014 at 08:31 PM..
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Unread 01-12-2014, 10:02 PM   #2
FarrellX
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does it sound like its really blowing but just isn't coming out? issue im having with mine...it gets super loud like it should be kicking ***...but its weeaakkkk
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Unread 01-13-2014, 06:31 AM   #3
colton_xj
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Quote:
Originally Posted by FarrellX View Post
does it sound like its really blowing but just isn't coming out? issue im having with mine...it gets super loud like it should be kicking ***...but its weeaakkkk
Exactly. The blower is going to town, but only a trickle of air comes of the vents. It eventually gets the cabin warm, but it takes forever and is lukewarm at best.
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Unread 01-13-2014, 07:36 AM   #4
AZ Jeff
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The heater box is set up so that, regardless of whether the "mode" doors are functioning correctly, when the blower is on "HIGH" setting, air WILL come out of the box SOMEWHERE. It may be the defrost (the default), or the floor, or the dash vents, but it will come out.

Are you saying when the blower is "going to town" that virtually NO air is coming out of ANY of those possible output points?
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Unread 01-13-2014, 09:00 AM   #5
colton_xj
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Quote:
Originally Posted by AZ Jeff View Post
Are you saying when the blower is "going to town" that virtually NO air is coming out of ANY of those possible output points?
Correct. With the blower on high, the airflow is even less than I would expect it to be on low, and it comes out of all points at more or less the same crappy speed.
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Unread 01-13-2014, 01:31 PM   #6
FarrellX
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i have the same issue with my 99. and the blower is SCREAMING hahahaha
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Unread 01-13-2014, 01:59 PM   #7
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I'm just throwing stuff out from the 1999 XJ Service Manual. Maybe something will help; maybe it won't. (I'm not a tech.)

Possible causes of an inoperative blower motor include:
Faulty fuse
Faulty blower motor circuit wiring or wire harness connectors
Faulty blower motor resistor
Faulty blower motor relay
Faulty blower motor switch
Faulty heater-A/C mode control switch
Faulty blower motor.
Possible causes of the blower motor not operating in all speeds include:
Faulty fuse
Faulty blower motor switch
Faulty blower motor resistor
Faulty blower motor circuit wiring or wire harness connectors.
**
VACUUM CHECK VALVE
A vacuum check valve is installed in the accessory vacuum supply line in the engine compartment, near the vacuum tap on the engine intake manifold. The vacuum check valve is designed to allow vacuum to flow in only one direction through the accessory vacuum supply circuits.

The use of a vacuum check valve helps to maintain the system vacuum needed to retain the selected heater-A/C mode settings. The check valve will prevent the engine from bleeding down system vacuum through the intake manifold during extended heavy engine load (low engine vacuum) operation.

The vacuum check valve cannot be repaired and, if faulty or damaged, it must be replaced.
**
VACUUM RESERVOIR
The vacuum reservoir is mounted to the front bumper bar behind the passenger side bumper end cap. The bumper end cap must be removed from the vehicle to access the vacuum reservoir for service.

Engine vacuum is stored in the vacuum reservoir. The stored vacuum is used to operate the vacuum-controlled vehicle accessories during periods of low engine vacuum such as when the vehicle is climbing a steep grade, or under other high engine load operating conditions.

The vacuum reservoir cannot be repaired and, if faulty or damaged, it must be replaced.
*
MODE DOOR VACUUM ACTUATOR
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, Refer to PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

DEFROST DOOR ACTUATOR
Disconnect and isolate the battery negative cable.
Remove the instrument panel assembly from the vehicle. Refer to Instrument Panel Assembly in Instrument Panel Systems for the procedures.
Unplug the two vacuum harness connectors from the defrost door actuator Defrost, Floor, and Panel/Demist Door Vacuum Actuators
Insert a trim stick or another suitable wide flat-bladed tool into the latch hole on the heater-A/C housing actuator mount Vacuum Actuator Remove/Install - Typical Gently pry the actuator latch while pulling firmly outwards on the actuator to remove the actuator from the mount
Rotate and tilt the vacuum actuator as required to disengage the hole on the end of the actuator link from the hooked pin on the end of the defrost door lever.
Remove the defrost door vacuum actuator from the vehicle.
Reverse the removal procedures to install.
FLOOR DOOR ACTUATOR
Disconnect and isolate the battery negative cable.
Remove the instrument panel assembly from the vehicle. Refer to Instrument Panel Assembly in Instrument Panel Systems for the procedures.
Unplug the vacuum harness connector from the floor door actuator Defrost, Floor, and Panel/Demist Door Vacuum Actuators
Insert a trim stick or another suitable wide flat-bladed tool into the latch hole on the heater-A/C housing actuator mount Vacuum Actuator Remove/Install - Typical Gently pry the actuator latch while pulling firmly outwards on the actuator to remove the actuator from the mount.
Rotate and tilt the vacuum actuator as required to disengage the hole on the end of the actuator link from the hooked pin on the end of the floor door lever.
Remove the floor door vacuum actuator from the vehicle.
Reverse the removal procedures to install.
PANEL/DEMIST DOOR ACTUATOR
Remove the defrost door actuator from the heater-A/C housing. See Defrost Door Actuator in this group for the procedures.
Unplug the vacuum harness connector from the panel/demist door actuator Defrost, Floor, and Panel/Demist Door Vacuum Actuators
Insert a trim stick or another suitable wide flat-bladed tool into the latch hole on the heater-A/C housing actuator mount Vacuum Actuator Remove/Install - Typical Gently pry the actuator latch while pulling firmly outwards on the actuator to remove the actuator from the mount.
Rotate and tilt the vacuum actuator as required to disengage the hole on the end of the actuator link from the hooked pin on the end of the panel/demist door lever.
Remove the panel/demist door vacuum actuator from the vehicle.
Reverse the removal procedures to install.
RECIRCULATION AIR DOOR ACTUATOR
A recirculation air door and vacuum actuator are used only on models with the optional air conditioning system.

Disconnect and isolate the battery negative cable.
Remove the kick cover from the heater-A/C housing. See Kick Cover in this group for the procedures.
Unplug the vacuum harness connector from the recirculation air door actuator Recirculation Air Door Vacuum Actuator Remove/Install
Insert a trim stick or another suitable wide flat-bladed tool into the latch hole on the heater-A/C housing actuator mount Vacuum Actuator Remove/Install - Typical Gently pry the actuator latch while pulling firmly outwards on the actuator to remove the actuator from the mount.
Rotate and tilt the vacuum actuator as required to disengage the hole on the end of the actuator link from the hooked pin on the end of the recirculation air door lever.
Remove the recirculation air door vacuum actuator from the vehicle.
Reverse the removal procedures to install.
*
HEATER PERFORMANCE
Before performing the following tests, Refer to Cooling System for the procedures to check the radiator coolant level, serpentine drive belt tension, radiator air flow and the radiator fan operation. Also be certain that the accessory vacuum supply line is connected at the engine intake manifold.

MAXIMUM HEATER OUTPUT
Engine coolant is delivered to the heater core through two heater hoses. With the engine idling at normal operating temperature, set the temperature control knob in the full hot position, the mode control switch knob in the floor heat position, and the blower motor switch knob in the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the heater-A/C housing floor outlets. Compare the test thermometer reading to the Temperature Reference chart.

Temperature Reference
Ambient Air Temperature 15.5° C(60° F) 21.1° C(70° F) 26.6° C(80° F) 32.2° C(90° F)
Minimum Air Temperature at Floor Outlet 62.2° C(144° F) 63.8° C(147° F) 65.5° C(150° F) 67.2° C(153° F)


If the floor outlet air temperature is too low, Refer to Cooling System to check the engine coolant temperature specifications. Both of the heater hoses should be hot to the touch. The coolant return heater hose should be slightly cooler than the coolant supply heater hose. If the return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the cooling system. Refer to Cooling System for the procedures.

OBSTRUCTED COOLANT FLOW
Possible locations or causes of obstructed coolant flow:

Pinched or kinked heater hoses.
Improper heater hose routing.
Plugged heater hoses or supply and return ports at the cooling system connections.
A plugged heater core.
If proper coolant flow through the cooling system is verified, and heater outlet air temperature is still low, a mechanical problem may exist.

MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat:

An obstructed cowl air intake.
Obstructed heater system outlets.
A blend-air door not functioning properly.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be adjusted with the temperature control knob on the heater-A/C control panel, the following could require service:

The heater-A/C control.
The temperature control motor.
The blend-air door.
Improper engine coolant temperature.
*
VACUUM SYSTEM
Vacuum control is used to operate the mode doors in the heater-only and heater-A/C housings. Testing of the heater-only and heater-A/C mode control switch operation will determine if the vacuum, electrical, and mechanical controls are functioning. However, it is possible that a vacuum control system that operates perfectly at engine idle (high engine vacuum) may not function properly at high engine speeds or loads (low engine vacuum) This can be caused by leaks in the vacuum system, or a faulty vacuum check valve.

A vacuum system test will help to identify the source of poor vacuum system performance or vacuum system leaks. Before starting this test, stop the engine and make certain that the problem is not a disconnected vacuum supply tube at the engine intake manifold vacuum tap or at the vacuum reservoir.

Use an adjustable vacuum test set (Special Tool C-3707-B) and a suitable vacuum pump to test the heater-A/C vacuum control system. With a finger placed over the end of the vacuum test hose probe Adjust Vacuum Test Bleed Valve , adjust the bleed valve on the test set gauge to obtain a vacuum of exactly 27 kPa (8 in. Hg.) Release and block the end of the probe several times to verify that the vacuum reading returns to the exact 27 kPa (8 in. Hg.) setting. Otherwise, a false reading will be obtained during testing

VACUUM CHECK VALVE
Remove the vacuum check valve. The valve is located in the vacuum supply tube (black) at the heater-A/C system vacuum tee.
Connect the test set vacuum supply hose to the heater-A/C control side of the valve. When connected to this side of the check valve, no vacuum should pass and the test set gauge should return to the 27 kPa (8 in. Hg.) setting. If OK, go to Step 3. If not OK, replace the faulty valve.
Connect the test set vacuum supply hose to the engine vacuum side of the valve. When connected to this side of the check valve, vacuum should flow through the valve without restriction. If not OK, replace the faulty valve.
HEATER-A/C CONTROLS
Connect the test set vacuum probe to the heater-A/C vacuum supply (black) tube at the tee in the engine compartment. Position the test set gauge so that it can be viewed from the passenger compartment.
Place the heater-A/C mode control switch knob in each mode position, one position at a time, and pause after each selection. The test set gauge should return to the 27 kPa (8 in. Hg.) setting shortly after each selection is made. If not OK, a component or vacuum line in the vacuum circuit of the selected mode has a leak. See the procedure in Locating Vacuum Leaks
CAUTION: Do not use lubricant on the switch ports or in the holes in the plug, as lubricant will ruin the vacuum valve in the switch. A drop of clean water in the connector plug holes will help the connector slide onto the switch ports.

LOCATING VACUUM LEAKS
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, Refer to PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

Disconnect the vacuum harness connector behind the glove box and inboard of the glove box opening on the heater-A/C housing.
Connect the test set vacuum hose probe to each port in the heater-A/C housing half of the vacuum harness connector, one port at a time, and pause after each connection Vacuum Circuit Test The test set gauge should return to the 27 kPa (8 in. Hg.) setting shortly after each connection is made. If OK, replace the faulty heater-A/C control. If not OK, go to Step 3
Determine the vacuum line color of the vacuum circuit that is leaking. To determine the vacuum line colors, refer to the Vacuum Circuits chart Vacuum Circuits - Heater Only or Vacuum Circuits - Heater-A/C
Disconnect and plug the vacuum line from the component (fitting, actuator, valve, switch, or reservoir) on the other end of the leaking circuit. Instrument panel disassembly or removal may be necessary to gain access to some components. See the service procedures in this group.
Connect the test set hose or probe to the open end of the leaking circuit. The test set gauge should return to the 27 kPa (8 in. Hg.) setting shortly after each connection is made. If OK, replace the faulty disconnected component. If not OK, go to Step 6.
To locate a leak in a vacuum line, leave one end of the line plugged and connect the test set hose or probe to the other end of the line. Run your fingers slowly along the line while watching the test set gauge. The vacuum reading will fluctuate when your fingers contact the source of the leak. To repair the vacuum line, cut out the leaking section of the line. Then, insert the loose ends of the line into a suitable length of 3 millimeter (0.125 inch) inside diameter rubber hose.
*
BLOWER MOTOR RESISTOR
For circuit descriptions and diagrams, refer to 8W-42 - Air Conditioning/Heater in Wiring Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, Refer to PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

Disconnect and isolate the battery negative cable.
Remove the kick cover from the heater-A/C housing and unplug the wire harness connector from the blower motor resistor.
Check for continuity between each of the blower motor switch input terminals of the resistor and the resistor output terminal. In each case there should be continuity. If OK, repair the wire harness circuits between the blower motor switch and the blower motor resistor or blower motor relay as required. If not OK, replace the faulty blower motor resistor.
* BLOWER MOTOR SWITCH
For circuit descriptions and diagrams, refer to 8W-42 - Air Conditioning/Heater in Wiring Diagrams.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, Refer to PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

Check for battery voltage at the fuse in the Power Distribution Center (PDC) If OK, go to Step 2. If not OK, repair the shorted circuit or component as required and replace the faulty fuse.
Turn the ignition switch to the Off position. Disconnect and isolate the battery negative cable. Remove the heater-A/C control from the instrument panel. Check for continuity between the ground circuit cavity of the heater-A/C control wire harness connector and a good ground. There should be continuity. If OK, go to Step 3. If not OK, repair the open circuit to ground as required.
With the heater-A/C control wire harness connector unplugged, place the heater-A/C mode control switch knob in any position except the Off position. Check for continuity between the ground circuit terminal and each of the blower motor driver circuit terminals of the heater-A/C control as you move the blower motor switch knob to each of the four speed positions. There should be continuity at each driver circuit terminal in only one blower motor switch speed position. If OK, test and repair the blower driver circuits between the heater-A/C control connector and the blower motor resistor as required. If not OK, replace the faulty heater-A/C control unit.
*
BLOWER MOTOR RELAY
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, Refer to PASSIVE RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

RELAY TEST
The blower motor relay Blower Motor Relay is located in a wire harness connector that is secured to the heater-A/C housing behind the glove box on the passenger side of the vehicle, next to the heater-A/C wire harness connector in the passenger compartment. Remove the relay from its connector to perform the following tests:

A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 2. If not OK, replace the faulty relay.
Resistance between terminals 85 and 86 (electromagnet) should be 75 ± 5 ohms. If OK, go to Step 3. If not OK, replace the faulty relay.
Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, see the Relay Circuit Test procedure in this group. If not OK, replace the faulty relay
RELAY CIRCUIT TEST
For circuit descriptions and diagrams, refer to 8W-42 - Air Conditioning/Heater in Wiring Diagrams.

The relay common feed terminal cavity (30) is connected to fused battery feed directly from a fuse in the Power Distribution Center (PDC), and should be hot at all times. Check for battery voltage at the connector cavity for relay terminal 30. If OK, go to Step 2. If not OK, repair the open circuit to the PDC fuse as required.
The relay normally closed terminal cavity (87A) is not used for this application. Go to Step 3.
The relay normally open terminal cavity (87) is connected to the blower motor. When the relay is energized, terminal 87 is connected to terminal 30 and provides full battery current to the blower motor feed circuit. There should be continuity between the connector cavity for terminal 87 and the blower motor relay output circuit cavity of the blower motor wire harness connector at all times. If OK, go to Step 4. If not OK, repair the open circuit to the blower motor as required.
The coil battery terminal cavity (86) is connected to the ignition switch. When the ignition switch is placed in the On position, fused ignition switch output is directed from a fuse in the junction block to the relay electromagnetic coil to energize the relay. There should be battery voltage at the connector cavity for relay terminal 86 with the ignition switch in the On position. If OK, go to Step 5. If not OK, repair the open circuit to the junction block fuse as required.
The coil ground terminal cavity (85) is connected to ground. This terminal supplies the ground for the relay electromagnet coil. There should be continuity between the connector cavity for relay terminal 85 and a good ground at all times. If not OK, repair the open circuit as required.
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Unread 01-13-2014, 02:41 PM   #8
CCKen
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Quote:
Originally Posted by colton_xj View Post
Correct. With the blower on high, the airflow is even less than I would expect it to be on low, and it comes out of all points at more or less the same crappy speed.
I think you may have some foam or other material inside the HVAC blocking the airpath directly downstream of the blower air chamber.

A preliminry check is to roll down the glove box (release the rubber stops and let the glove box hang on its hinge) and look in the recirculation air inlet and see if there's any crap near the blower fan. The Recirc door must be in the 'Recirc" position. See pic.



Q: Do you see any black or gray foam bits coming out of the air outlets?
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Unread 01-13-2014, 08:21 PM   #9
colton_xj
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Thanks for the suggestions, guys.

Quote:
Originally Posted by CCKen View Post
A preliminry check is to roll down the glove box (release the rubber stops and let the glove box hang on its hinge) and look in the recirculation air inlet and see if there's any crap near the blower fan.
It's pretty clean in there.

Quote:
Originally Posted by CCKen View Post
Q: Do you see any black or gray foam bits coming out of the air outlets?
No, nothing seems to be blowing out.

--------------------------------------------

I went ahead and removed the dash so I could see what was going on, and it appears that the vent actuators aren't moving smoothly. After cycling them a few times by hand, the floor and face vents seem to be working pretty well, if a bit slowly, but the defrost and recirc vents are either shot or not getting enough suction to operate. Either way, they don't cycle unless I force them by hand, which kind of fits the Jeep's symptoms, since four partially open vents would create enough turbulence to waste most of the air pressure.

I also found a piece between the vacuum hose and throttle body that looks like a tiny inline fuel filter, which doesn't allow much flow, so I removed it, but it didn't seem to make any difference. Not sure if that's a factory part or something that was added in the fifteen years before this Jeep came to me.

I guess that means I have a vacuum leak somewhere downstream from the engine bay. I'll try to run it down and report back. In the meantime, I'd welcome any other advice or suggestions.
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Unread 01-14-2014, 08:34 AM   #10
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Quote:
Originally Posted by colton_xj View Post
Thanks for the suggestions, guys.


It's pretty clean in there.


No, nothing seems to be blowing out.

--------------------------------------------

I went ahead and removed the dash so I could see what was going on, and it appears that the vent actuators aren't moving smoothly. After cycling them a few times by hand, the floor and face vents seem to be working pretty well, if a bit slowly, but the defrost and recirc vents are either shot or not getting enough suction to operate. Either way, they don't cycle unless I force them by hand, which kind of fits the Jeep's symptoms, since four partially open vents would create enough turbulence to waste most of the air pressure.

I also found a piece between the vacuum hose and throttle body that looks like a tiny inline fuel filter, which doesn't allow much flow, so I removed it, but it didn't seem to make any difference. Not sure if that's a factory part or something that was added in the fifteen years before this Jeep came to me.

I guess that means I have a vacuum leak somewhere downstream from the engine bay. I'll try to run it down and report back. In the meantime, I'd welcome any other advice or suggestions.
If your cruise control works fine even under various loads, like going up and down hills, it would seem the vacuum problem is in the HVAC system, but that remains to be seen

That 'tiny inline inline fuel filter' is the HVAC check valve (see pic below) and is need in the system.

JeepCares' posting, showing how to check this check valve, under "VACUUM CHECK VALVE" should be accomplished. If the valve fails a new one can be obtined from the dealer. Above this is a paragraph entitled "VACUUM CHECK VALVE" as well. This addresses the check valve at the intake manifold. It should be tested as well. See pic below.

I used a Harbor Freight vacuum hand pump brake bleeder to check my vacuum system (see pic) and it worked good.

If your HVAC doors are sluggish it would indicate a lower than 8 in/hg vacuum available at the actuators (FSM test spec). If you are going to test the system with the hand pump see how they work with only 8 in/hg. With the engine running at idle you should have approxmately 17-22 in/hg vacuum in the system, which should be ample enough to move the doors. Pump the vacuum down to 17-22 in/hg and see if the doors operate properly. If not, there could be an actuator vacuum hook up leak.

Vacuum system:



Vacuum circuits:



Vacuum source at intake:



HVAC check valve:



Vacuum test - with engine removed for clarity LOL



Vacuum plumbing at cruise control servo:



Vacuum reservoir:

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Unread 01-14-2014, 12:54 PM   #11
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Great post Ken!
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Unread 01-14-2014, 01:16 PM   #12
colton_xj
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Yes, indeed! Thanks for the in-depth post, Ken, and thanks for the FSM procedures Lee.

Question: Are the doors supposed to be spring-loaded so they default to a particular position, or is that movement also powered somehow? Mine seem to be sluggish in every direction, not just the direction powered by suction.

I had to reassemble the dash (except the trim) last night so I could drive it to work this morning, and I won't have a chance to work on it again until this weekend, but I'll try your suggestions and report back.
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Unread 01-20-2014, 02:41 PM   #13
colton_xj
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Well, I had time to dig back into it, but I'm not making any progress.

I've verified that I have vacuum into the cab. Nothing in the engine bay seem to be leaking, though the check valve is shot. I used my bleeder at the HVAC vacuum port and things move about the same as when the engine is running, which is to say sluggishly. I took apart the HVAC vacuum harness, found that the recirculator line was totally plugged, and fixed that. The recirc door operates now, but never totally closes. I also found that there's a gap between the HVAC box and the defrost vent, which may explain why I'm not getting much flow through the center defrost, while the side defrost vents are okay.

Bottom line, everything is cycling, but it's sluggish and nothing opens or closes the whole way. There's always a bit of air coming out of the face vents, and the air is always cold or tepid at best.

I'm trying to go back to square one in case I missed something, so I pulled the hoses and ran water through the core, which came out clean. I also checked the blend door: The motor is working, and I'm able to turn the door by hand.

Honestly, I'm at my wits end with this thing, but I don't want to pay a shop to retrace all my steps. I may just start looking for a salvage HVAC box.

In the mean time, any suggestions are welcome. I really appreciate the help.

Last edited by colton_xj; 01-20-2014 at 03:41 PM..
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Unread 01-20-2014, 05:23 PM   #14
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dry harness

I got a 98 GCL 5.9..had a similar problem with heater drawing me to the blend door.after taking down glovebox and seeing the careful detail to the wrap of every factory connector. I decided to flex every joint I could reach.Works normal again.Good Luck.
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Unread 01-20-2014, 05:32 PM   #15
chris87xj
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Might as well throw this in the mix as well.
Quote:
Originally Posted by chris87xj View Post
The 4897610AA blend door on later gen XJs is known to have problems with THIS causing need for THAT.
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Better to hoard Jeep technical info than old newspapers and the neighbor's mail, I guess.......
ENTER your jeep in the September Cherokee Of The Month contest here!!
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