Troubleshooting Guide For Mercedes Sprinter Van Blower Not Working
When the blower in a Mercedes Sprinter van stops working, the cause is almost always one of four things: a blown fuse, a damaged blower resistor, a bad ground connection on the motor, or a failed speed control module (or the motor itself). Check them in that order with a test light or multimeter, starting at the fuse box.
The blower in the heating and air conditioning system sets how fast warm or cold air is pushed into the cabin, and you need it to clear a fogged windscreen. A failed blower motor gives weak or no airflow from the vents. The blower motor usually sits under the glove box on the passenger side, so it is easy for a mechanic to reach and replace.
TL;DR
- Common causes: blown fuse, damaged resistor, bad motor ground, failed speed control module or motor.
- Step 1: check the blower fuse and replace it if blown.
- Step 2: with the blower switched on, the motor plug should show 9 to 11 volts.
- Power at the plug but no fan: test the motor on jumper leads; replace the connector or the motor.
- No power at the plug: test the switch (0.01 to 0.03 ohms when on), then the wiring harness.
- Blower motor screws are tightened to 2 Nm (17 in. lbs.).
- If this is not your case, read why the Sprinter radio is not working.
Table Of Content
- Why is my Sprinter van blower not working?
- How do I find which blower part has failed?
- Is a Sprinter blower motor hard to replace?
Why Is My Sprinter Van Blower Not Working?
The Mercedes Sprinter van blower motor is located underneath the passenger side dashboard. These are the most common faults:
- A blown fuse
- A damaged resistor
- A faulty ground connection on the motor
- A malfunctioning speed control module
If the blower runs but the airflow is weak, also check the cabin filter: see the Sprinter cabin air filter replacement guide.
How Do I Find Which Blower Part Has Failed?
Isolate the motor and do some basic electrical tests to find the reason the blower fan has failed. You need a good understanding of electrics and experience with electrical test equipment.
It also helps to have the wiring diagram for your vehicle; the fuse allocation for your van is in the Mercedes-Benz owner's manual. Follow all the usual safety precautions when working with electricity.
| Test | Expected result | If the result is wrong |
|---|---|---|
| Blower fuse | Fuse intact | Replace the fuse |
| Power at the blower motor plug, blower on | 9 V to 11 V, or the test light glows | Go to the switch test (Step 4) |
| Motor on jumper leads | Motor turns | Motor turns: replace the connector. Motor still dead: replace the motor |
| Switch resistance, switch on | 0.01 to 0.03 ohms | No reading on any setting: replace the switch |
| Power at the switch connector | Test light glows or correct voltage | Trace the harness to the battery for a break |
| Blower motor retaining screws | Tightened to 2 Nm (17 in. lbs.) | Retighten |
STEP 1: First, Check The Fuses
A blown fuse often causes a component to fail. If the fuse has blown, replace it; if not, move on to step 2.
STEP 2: Examine The Motor For Power
Unplug the blower motor and use a test light or a multimeter set to volts. Connect the black lead to a good ground, such as a bolt on the engine block, switch the blower on, and probe the plug that normally connects to the blower motor with the red lead.
The test light will glow if the meter reads between 9 and 11 volts. If the voltage is correct or the test light glows, go to Step 3. If not, skip to Step 4.
STEP 3: Check The Blower Motor's Connection
You need two jumper leads, one black and one red. Connect the black lead to ground first, then to the blower motor assembly. Connect the red lead to a power source, then to the terminals on the motor side of the unplugged connector.
If the motor turns, the connector is bad: replace the connector. If the motor still won't turn, replace the motor with a new one.
The Blower Motor Is Not Working: Replacement
A blower motor that does not work is one of the first signs of a bad blower motor relay. The relay is the switch that sends current to the blower motor, so if it fails internally, the circuit loses power, the motor stops and the vents stop blowing air.
The blower system has three parts: the blower motor, the blower resistor and the control panel. On the high-speed setting the resistor is bypassed, so testing on high helps rule it out.
A faulty blower motor is the most common problem. It sits on the passenger side.
Turn the key on, set the control to high, and tap the blower motor firmly in several places. A sticking motor can often be freed this way.
With the key on and the blower on high, check the red/blue wire at the blower for power with a meter or test light. If there is no power, suspect the control panel; if there is power, suspect the blower motor. Tapping on it might free it up.
Removal Of The Blower Motor
- Disconnect and isolate the negative battery cable.
- Remove the air cleaner housing cover from the engine.
- Move the ventilation housing insulation blanket out of the way of the blower motor assembly.
Assembly For Blower Motor
- Disconnect the blower motor's wire harness connector.
- Remove the three retaining screws on the blower motor.
- Remove the blower motor assembly from the ventilation housing.
Installation Of The Blower Motor
- Place the blower motor assembly in the ventilation housing.
- Install the three retaining screws and tighten them to 2 N.m (17 in. lbs.).
- Connect the wire harness connector to the blower motor.
- Refit the ventilation housing insulation blanket.
- Refit the air cleaner housing cover on the engine.
- Reconnect the negative battery cable.
STEP 4: Perform A Test On The Switch
Reconnect the connector to the blower motor, then follow the wire harness back to the connector nearest the blower motor switch, which is normally under the dash. Unplug that connector and set the multimeter to ohms.
Put one lead on one of the connector's prongs and the other lead on the power-in prong, making sure they don't touch. With the switch on, the reading should be between 0.01 and 0.03 ohms.
Switch resistance varies, so a slightly higher reading is fine. If you get no reading on any switch setting, the switch is faulty and should be replaced.
STEP 5: Check To Determine If The Battery Is Providing Power To The Switch
Leave the switch unplugged and set the multimeter to volts, or use a test light. Ground the black lead as before and probe the connector with the red lead. The hot (power) wire is usually green or red.
If the wire colour is unclear, check the wiring diagram for your van. If the meter shows the right voltage or the test light glows, the switch is getting power: skip to Step 7. If not, go to Step 6.
STEP 6: Examine The Electrical Harness For A Break
If the test light does not glow or the meter reads zero, there is a break in the harness between the switch and the battery. Follow the harness, checking the hot wire for power at each junction, until you find the break. Repair it.
STEP 7: Examine The Wire Between The Switch And The Fan For A Break
If the switch and motor both test good and the meter shows voltage (or the light glows), follow the harness between the two as closely as you can, looking for burned patches or broken wires. Repair or replace the harness once you find the break.
Is A Sprinter Blower Motor Hard To Replace?
Following the steps above should tell you why the Sprinter blower has failed.
Replacing the blower motor isn't difficult, because it is usually easy to reach. A mechanic will usually remove the passenger side glove box and the side panels in the passenger footwell.
The bolts come out of the motor, the power wires are unplugged, and a new motor goes in. The job is simple, but the parts can be expensive. If the problem is with remote climate control rather than the blower itself, read Mercedes pre-climate control not working.
Mercedes Sprinter Problems-