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E23 7series Heater A/C Fan Removal & Reinstallation
First you must remove the leaf grills just in front of the windshield, there are 2 screws in the center, and several spring clips that hold it in place. The drivers side comes out first, then the passenger side. Gently lift against the spring clips and they snap right out. As you raise these up, take care that they release from the windshield washer nozzles which remain attached to the cowling cover.
The engine compartment seal needs to be pulled up out of the way the width of the firewall, just gently lift on the rubber and work it up and out of the way clear to both sides.
There are ~15 screws holding the cowling cover in place, 2 horizontal ones on each side, 4 vertical ones across the back, and 5 or 6 across the front of the firewall. Remove them all, taking care not to lose any of the wire hangers they may hold into place. There are 4 screws, 2 on each side holding the vent intake grills in place that DO NOT need to be removed.
Gently lift the cowl cover up, easiest if you lift the front first, then move it forward until you clear the wipers. There are 2 vacuum hoses on the drivers side, and one on the passenger side that you can unplug from the smog vent servos. The hose to the windshield washers fits in a series of retaining clips under the very front of the cowl cover, I found it best to unclip the hose from 3 clips on both sides, as this allows enough slack to set the cowl cover out of the way in the engine compartment without actually removing all the hoses.
Now you can see the blower in the center. There is an air deflector mounted just a few inches outboard on both sides, it is simply a bent piece of sheet metal, held in place by a couple of clips. If you simply pull straight up on them, they will release and you can just lay them in the bottom of the tray, or if you want, remove them entirely, but it is not necessary.
The black plastic shrouds around the blower squirrel cages are an intricate piece of work, designed I believe by the same genius that gave us the rubix cube, but don't be afraid, it can be done. The plastic shrouds are held in place by a metal band with a snap release on each side. After you release each snap, you may find it helpful to use some wire ties or rubber bands attached to the wiper blades to hold the rear bands out of way, but don't cinch them too tight, you need to flex them some to remove the shroud pieces. Each squirrel cage cover consists of 4 removable plastic pieces, which fit together very precisely and for the most part are not interchangeable, so keep them separate as you remove them or you will be even more perplexed when it's time to reassemble. First lift up on the top half of one of the black plastic "arches" to release it from the bottom half. There is now a round grill piece about 5" in diameter on each outboard side, which must be removed by pulling downward if it came off with the upper arch, or if it happened to stay on the lower half by lifting upwards. These simply friction fit to the arch shape piece and should release with minimal pressure. On the inboard side of each shroud is a similar but smaller piece, shaped kind of like a semi-circle which releases by pulling downward. These must be removed before you can remove the upper shroud cover! There is also a lower "semi-circular piece inboard on each side, but with any luck they will stay in place and you won’t have to mess with them. Be aware that most of these pieces fit together so precisely that at first glance you would swear that they are one piece!
Before trying to remove the upper arch pieces, there are 2 8mm bolts which hold the thermostat and the blower motor retaining strap, and by removing them you can now rock the motor/cages assembly slightly from side to side by lifting on the opposing side, which gains you some critical wiggle room as you move the upper halves to the outside edge. I always remove the passenger side arch completely, and just move the drivers side to a point where it is out of the way, and clears the outer edge of the squirrel cages. Be very careful moving each arch piece, this is one of the most challenging parts of this whole ordeal, much care must be used not to damage the plastic squirrel cages, it takes some time and patience, and the retainer bands need to be flexed to get the arches off to each side, but it can be done, honest!
Once you have the 3 plastic pieces from one side out, spend a few minutes fitting them together so that you are familiar with how they go back together, this will help you immensely when you are trying to get them back together on the car. The circular grill and semi-circular pieces, slide into the concave edges of the upper halves of the squirrel cage covers, and friction fit precisely into them. They fit almost flush with the sides of the covers, but if you look carefully at the edges of the small pieces, you will notice alternating tabs that create a channel to receive the plastic edge of the cover.
Remove the thermostat, which was held in place by the same 2 bolts that hold the motor down, by lifting it gently up and forward, paying careful attention to the sensor lead which is threaded down into the heater core itself, be careful not to kink the stiff wire. You can unplug the wires on this, just remember that the red one goes toward the rear of the car, notice how the sensor wire comes out of the core, you will need to replace it in the same manner. There is a small channel mounted on the top surface of the heater core which guides the sensor wire back in.
Now unplug the fan power harness, lift the fan motor retaining strap out of the way, and gently move the fan motor and cages towards one side or the other of the car, I think it will come out on either side, but I have always done it towards the passenger side, once you have moved the fan about 5 inches it will lift right out. Notice that on the fan motor itself, one end is nearly squared off, and the other end protrudes out somewhat, the end with the protrusion should face the passenger side of the car. There is also a small index bump towards the passenger side, that you will need to line up with a hole in the retraining strap, now is a good time to identify it. As you put the new fan in, be certain to move the retaining strap out of the way so it doesn't damage those delicate squirrel cages, and as you move the assembly back towards the center of the car, beware of the metal straps that hold the cage covers on, they must be flexed a little to keep them out of the way of the fan assembly. Once you have the new fan in position, make sure that the large vent hole is on the bottom, and that the small index hump lines up with the hole on the retaining strap, the index bump is so shallow that it is easy to miss. Proper alignment at this point is critical, as you could break the motor saddle if it is not positioned correctly. Test fit the motor BEFORE installing the bolts, the mating surfaces strap should meet with very little pressure. Before you bolt the fan in place, get the upper halves of the covers back into position above each cage using the rocking action outlined above. Replace the thermostat, making sure the stiff sensor wire gets threaded down into it's hole in the heater core, replace the retaining strap, then bolt the thermostat and strap back down. Don't forget those wires to the thermostat, red on the lug towards the rear of the car, and plug in the power harness to the fan motor itself. .
Take a break now, because the next few steps will make you wonder why you started this project, and you may seriously doubt that this stuff all fit together once! Take one of the inboard semi-circular pieces and position it where it belongs on the lower half of the squirrel cage cover, this requires holding the upper half up slightly, and there are some tiny indexing notches that help keep them in place, once they are in place, gently slide the upper half down, making sure that the tabs friction fit onto it. Once it is in position you can lift the upper half and the semi-circular piece will usually remain with the upper part, while you get the outer circular grill into position. You will notice that each circular grill has a flat side, and that side must sit against the bottom of the firewall tray, carefully position it, and slide it down onto the lower arch piece, remember that the little channel friction fits on that half as well, and once positioned slide the upper arch down so that it fits into the grooves and friction fits. Use a flashlight to check all the mating surfaces to be certain that they are in the proper position before you snap the metal retaining band back down. Replace the second cover in the same way, then hop in the car and test the motor, wow, it should be quiet and powerful, assuming everything up to this point went smoothly.
Replace the metal deflector plates on each side, replace all the vacuum lines, snap the washer hose back up into the clips under the front of the cowl cover, then reinstall the cowl cover carefully. This usually goes pretty smoothly, but sometimes a small screwdriver may help to get thing started, just to pry the firewall out enough to allow it to fit, it is tight. Check to make sure the screws line up with the holes in the cowl cover, I also recommend that you check the smog setting on the car, to be certain that the flaps on each side of the cowl close when it is pressed (vacuum must be present). Tighten all the screws, put the leaf guards back, passenger side first, taking care to insure that the covers fit properly over the washer jets. Replace the 2 center screws into the leaf guards, slide the engine compartment gasket back into place, and you are done!
The first time I did this, it took me 3+ hours, but once you have done it, it should only take about an hour.
Many thanks to Karl Preisach for his help in writing and remembering this procedure!!!
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