A detailed step-by-step explanation on how to replace the heater blower motor in a BMW 2002.
Degree of difficulty: Advanced
Required Tools & Parts To Replace Heater Blower Motor
- 10-mm socket with extension bar and ratchet
- BMW tool kit (with Phillips head screwdriver bit)
- 7-mm open or box end wrench
- Long-handled regular screwdriver
- Needle nose pliers
- Pop rivets and pop rivet tool (assorted sizes)
- Electrical drill with drills
- 4 small corks for plugging heater hoses and heater core tubes
- Newspaper and paper towels
- (2) alligator clip test/temporary connection wires
- (1), 2 quart container into which to drain coolant
- Ohmmeter (optional)
- PATIENCE and 3-8 hours (your mileage may vary).
- Remove the gearshift knob and shift the car into fourth gear.
- Take out radio, tape deck, CB, etc., if necessary to get at the screw in the base of the console just ahead of the gearshift lever. Remove screw from base. Find and remove the screw on the upper right (outboard) side of the console which holds the console to the dash. Unplug hazard warning light and other connections inside.
- Unscrew the four recessed screws (2 on each side) holding together the rear portion of the console. Lift up the section and remove. Pull up on hand-brake, move seats fully to the rear, and then lift, pull rearward, and remove the console.
- Remove all under-dash panels except for the extreme right and left ones.
- Remove the glove-box by unscrewing the three cap screws on the hinge at the rear of the box (actually the forward side in the car). Slide the box forward in the car and down to remove. (The two retaining arms on the sides make the maneuver a bit difficult.)
- Tie wiring up and out of the way. Turn heater blower switch to OFF. Remove the four wires from the terminal block at the upper left rear side of the black plastic heater box. Note the arrangement of the colored wires to the connection lugs on a piece of paper since it will be a while before you get back to this point.
- Release the pressure cap on the radiator, turn heater temperature control to cold. Under the cowl area under the hood remove the two heater hoses (one on each side). Plug the hoses and heater core tubes to prevent the coolant from dripping out. You will lose some coolant anyway, but this will prevent spilling a lot inside the car when you remove the heater box. Wipe up any spillage or other water in the area before continuing.
- Before moving to the removal of the heater box, study it's construction. The box is a two piece affair, consisting of a top front piece with the blower motor and temperature control valve (on the right) and a lower rear section containing the heater radiator core and most of the air distribution flaps. It is fastened together at the top with three rivets and at the bottom with three spring clips. The entire box is fastened to a rectangular hole in the upper firewall by two 10-mm nuts on two studs (one on either side). The box is removed by lowering and pulling to the left while turning the bottom up toward the rear of the car. There is very little room between the dash and other parts to do this. It takes a lot of patience the first several times. Remember the entire box is plastic!
If you are discouraged at this point or have run out of time, you can reconnect the heater hoses (Step 7) to be able to drive the car (only the directional signals will be inoperative). If you get further along you can pull the hose out of the firewall and connect them to each other with "flushing" tee or piece of pipe.
- In 1972 and later models the two heater and vent control lever assemblies can be removed from the dash. The cables can then be removed with the heater box. Pry out the cover plates (after pulling off the black knobs) from each control lever area. Unfasten the Phillips head screws which hold the units to the dash and remove the lever assemblies from behind the dash.
- Remove the 1O-mm retaining nuts, brown ground wires and other wiring harnesses attached to the box. Patiently and carefully lower the box, moving the left side down first and the most. Move the box slightly to the rear and rotate it so that the bottom is turned toward the rear of the car. The maneuver is limited severely by space. Take care not to crack the blower motor housing or bend the control cables sharply. With some maneuvering you should be able to get the box out.
- Drill out the three rivets at the top rear flange of the box, taking care not to mutilate the foam seal. Use a larger drill than you might at first think is necessary (about 3/16"). Remove the three spring clips on the bottom of the box and unfasten the clip on the lower left corner, if necessary, to take the box apart.
- Disconnect the heater control valve control cable with the 7mm wrench. Taking care that the valve is closed (lever rearward), uncork the valve, place the 1, 2-quart container under the end, and open the valve, draining as much coolant as possible out of the heater. Lift the left end to facilitate this job. Drain the left end next and replace the left end cork. Unfasten the heater temperature control valve from the plastic support bracket (very easy to break) and the heater core tube. Upon re-assembly this is the time to replace this valve if it needs it since there will never be an easier time.
- Pry the heater box apart about 3/4'', reach inside the upper-right side and, using a screwdriver, pry the other heater control cable off the inside air distribution flap. Repeat the procedure for the lower vent cables as required. Pull the two wires off the inside of the four lug terminal plate at the upper left side of the box. Now the box can be completely taken apart, carefully pulling the top off the heater core tubes.
- Remove the two wires from the blower motor, noting their locations and the four spring clips holding the motor in the housing. Remove the motor, noting it's position in the housing.
- Place the new motor in the housing and check for free spinning. If there is obstruction, the fan blades may be bent upward. Bend blades if necessary, checking the old motor for correct alignment and pitch.
- Now do all the steps in reverse, using a pop rivet gun to refasten the box together. Lacking a pop rivet gun, 4-mm bolts and nuts. After the box is back together, but before riveting, check for proper functioning of the motor using the temporary leads. The ohmmeter can be useful to trace connection problems. The green/brown lead and the white wire inside the heater box are positive. Certain steps, like refastening the control cables and the lower, heater box clips, are very difficult. When done, replace the coolant in the radiator and check the fuse. Some cars have a 25 amp fuse when only a 16 is required.
Author: Richard Hubbell