If the air in your Jeep blows hot on one side and cold on the other side, you likely have a broken blend box door. The door has a hinge on it that has been known to break rather easily. This prevents the door from opening, which prevents hot air from blowing into the vehicle. The blend doors also have actuators that open and close them when you turn the heat on and off. When these actuators fail, as all electronic parts eventually do, the doors will fail to open and no hot air will come out of your vents. Keep reading and we'll guide you through the process of diagnosing a blend box door issue.
Materials Needed
Getting to the blend box door itself involves removing the dash, which is a giant pain in the neck. But getting to the actuator is quite easy, so you can save yourself a lot of time and heartache by checking this first. Before you start, however, make sure that your coolant and R134 are topped off, as low levels can also cause this issue. The passenger's side actuator is located up underneath the dash, and can be spotted by laying on the floor and looking up (see Figure 1). Remove the motor and open it up (it simply slides up). Check the gears to see if they are gummed up. If they are, you can clean them with contact cleaner and it should solve the problem. If it looks clean, you can order a new actuator for around $150.
Figure 1. The actuators are located underneath the dash.
Figure 2. This actuator had seized up because of buildup on gears.
Step 2 – Check blend box doors
If your actuators are functioning properly, you most likely have a broken blend box door. Excessive heat can cause the doors to warp, which can break the hinges. The hinges themselves are also known to break over time and extended use, so this is a common problem. To replace the blend box doors in a Wrangler JK, you must remove the dash assembly, which is a very tedious job. Having a dealership complete this for you can cost upwards of $1,000 or more, so if you have the patience and capability to do it yourself, it can save you a lot of money.
Figure 3. Replacing the blend box doors requires removing the entire dash assembly.
Materials Needed
- Ratchet and common socket sizes
- Flat head screwdriver
- Contact cleaner
- Q-tips
Getting to the blend box door itself involves removing the dash, which is a giant pain in the neck. But getting to the actuator is quite easy, so you can save yourself a lot of time and heartache by checking this first. Before you start, however, make sure that your coolant and R134 are topped off, as low levels can also cause this issue. The passenger's side actuator is located up underneath the dash, and can be spotted by laying on the floor and looking up (see Figure 1). Remove the motor and open it up (it simply slides up). Check the gears to see if they are gummed up. If they are, you can clean them with contact cleaner and it should solve the problem. If it looks clean, you can order a new actuator for around $150.
Figure 1. The actuators are located underneath the dash.
Figure 2. This actuator had seized up because of buildup on gears.
Step 2 – Check blend box doors
If your actuators are functioning properly, you most likely have a broken blend box door. Excessive heat can cause the doors to warp, which can break the hinges. The hinges themselves are also known to break over time and extended use, so this is a common problem. To replace the blend box doors in a Wrangler JK, you must remove the dash assembly, which is a very tedious job. Having a dealership complete this for you can cost upwards of $1,000 or more, so if you have the patience and capability to do it yourself, it can save you a lot of money.
Figure 3. Replacing the blend box doors requires removing the entire dash assembly.
