The plastic blend door inside the HVAC box snaps from age, stuck on hot or cold. DIY repair via small panel cut without dash removal is the common workaround.
The blend door inside the XJ HVAC box mixes hot and cold air to set temperature. Made of brittle plastic, it cracks at the pivot or its actuator shaft and gets stuck - usually in the full-hot position, so summer driving becomes intolerable. Two paths: 1) full dash-out repair with new OE Dorman blend door 902-202 ($30), proper but 8+ hours; 2) the famous 'Mr. Smiley' style HVAC box cut - score and cut a small access panel in the HVAC box from inside the passenger footwell, fit and glue a replacement door, then tape the panel closed. Several detailed writeups on NAXJA describe the cut location. Total time for the cut method: 1-2 hours. The blend door actuator motor (Dorman 604-002) often fails with the door; replace both while you have access. Symptoms of actuator failure (vs door): clicking noise behind the dash when changing temp setting, no temperature change despite slider movement.
| Part | Vendor | Est. price |
|---|---|---|
| Blend door | Dorman | ~$30 |
| Blend door actuator | Dorman | ~$30 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.