Jeep WJ Grand Cherokee HVAC Sub Assembly Replacement Common Mistakes
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Replacing blend door and recirculation door components
Symptoms: Cold air only / No heat (passenger and/or drivers side)
A very common problem in 1999-2004 model Grand Cherokees has been weak blend and recirculation doors in the HVAC systems. The doors are turned by a motor attached to the bottom of the door at the end of a hinge shaft. The motor stops turning when there is enough physical resistance from the door stopping against its housing. This puts stress on the shaft/door junction and over time strips the shaft so that it spins almost independently of the door. The motor then experiences little resistance and keeps turning, which sends the “travel too large” code.In January of 2004 Jeep issued an informational TSB (#24-001-04) which introduced newly designed sub assemblies. The newly revised assemblies have stop tabs that stop the motor from turning, instead of relying on the weak shaft/door contact. It is recommended that the respective sub-assembly be installed if a blend air door(s), a recirculation door, a door link, or a sub-assembly housing requires replacement. The table below provides the part numbers for the new HVAC sub-assemblies.
Most common failures – The most common failures will require the replacement of the HVAC sub assemblies. This requires removal of the entire instrument panel assembly, a very involved process.
Least common failures – The least common failures are the door actuator motors. These should be checked first as they are the easist to replace (with one exception). The single motor for the Manual A/C system can be accessed and replaced by simply removing the glove box. The Auto AZC system uses 2 actuators. Only the drivers side actuator can be accessed from behind the glove box. If you are getting cold air/no heat on the drivers side only, there is a chance that drivers side actuator could be defective. If you have cold air/no heat on the passenger side, the actuator that controls this side requires removal of the entire dash and HVAC assembly.
HVAC sub assemblies (most common failures)
Cold air only / No heat on passenger and/or drivers side / Door travel too small / large
TSB #24-001-04NEW HVAC SUB-ASSEMBLY REPLACES BLEND OR RECIRC DOOR COMPONENTS