DIY- Fan Control Ampifier & Blower Fan Replacement 90-93 Q45 G50

[goody90q45]

I'm in a procedure-writing mood after spending most of the past two weeks off-and-on writing a 15 pager at work. The 90Q got a replacement fan control amplifier and blower motor yesterday and I thought I'd share the details. If you have a 94-96 Q45 the steps will be very similar. It's a pretty simple job but if you've never done this before (a caveman could do it) it could take many hours figuring out what has to be removed and how. Hopefully this tutorial will help.

The problem I'd been having was intermittent blower operation. The blower worked fine on all speeds on the cool morning drive to work but in the heat of the day it would not turn on. When the problem first started it would take 10-30 seconds for the fan to start but as the days went on and got hotter the blower wouldn't turn on at all. In the evening when it cooled down the blower operation returned to normal.

I had a spare blower fan and amplifier (from part cars) that I'd cleaned up and bagged a couple of years ago waiting for this moment. Plan on spending 1.5-2.5 hours to complete the work and a little more if you're going to clean up the fan blades for reuse.

Only a few basic hand tools are needed for this job. Sockets are 8mm and 10mm with a 1/4" drive ratchet, combination wrenches are also 8mm and 10mm. I also used needle nose pliers to unclip a couple of connectors and a few different length screwdrivers also came in handy. Don't forget the FSM, note paper, shop vacuum and bottle brush. The dense 2" thick foam pad (that the tools are on in the picture) helps the knees but doesn't protect the ribs on the door jamb (ouch!).



The fan control amplifier and blower fan assembly are both behind the glovebox so it will need to be removed. The first step is to disconnect the plastic tabs attached to the strings that hold the glovebox upright. Give the strings about 1" of slack and push down on the plastic clip. No need to remove the string from the clip.



Here are the fastener and string removed from the side of the glovebox.



With the glovebox strings disconnected and the door hanging down out of the way there's one screw on each hinge (green circle) to complete the door removal. In the picture, the right hinge is an Ace Hardware replacement for the cracked (and unreplaceable) OEM hinge.

Once the door is off remove the 10 screws (circled in red) around the perimeter of the glove box frame and pull it out. Two (or four?) of the screws may have a plastic cover that needs to be pryed off to expose the screws. They're on my 94Q but not this one.



There are 3 connectors (circled in red) on the back side that need to be unplugged to complete the glovebox frame removal. The 2 white connectors are the same and can be swapped when reassembling. Take note of which is which so you don't have to take everything back apart when you're done (like I did today) to swap connectors.



With the glove box frame removed the two components I'm looking to replace are almost accessible. The fan control amplifier is the rectangular piece in the middle and the blower fan is on the right. The amplifier can be removed now but the support bar in front of the blower will need to come off to remove it.



The fan control amplifier is removed by unplugging the connector in the center and then removing only the two 8mm outer bolts (circled in red). It's tempting but leave the two bolts in the middle alone.



Not the greatest picture but with the fan control amplifier removed you can see the dirty condenser partially plugged with leaves, some animal hair and other unidentified deretrius (sp?). I cleaned the condenser face with a bottle brush and a shop vacuum and the AC ran noticeably stronger and cooler last evening.



To remove the support bar in front of the blower fan, start by removing the last 2 screws (circled in red) holding the trim piece below the glove box. The 94-96 lower trim has clips, no screws, and will pull off without removing the glovebox. It's much easier to get to the ECU on the later G50's.



Flip the trim piece over and unplug the connector. On the 94-96 there will be additional airbag connectors that are unclipped from the panel but not unplugged. For reference, the screwdriver is holding back the carpet flap exposing the 10mm nut securing the passenger side kick panel which covers the ECU.



Remove the one screw holding in the trim piece on the far right side of the support bar. This piece covers a couple of screws holding the support bar.



Remove the two 8mm bolts on the left end of the support bar.



Remove the two screws and 10mm nut (all circled in red) on the right end of the support bar. Pull out the support bar and set it aside.



This wire junction block will need to be loosened in order to make clearance for the blower fan to be removed. Three screws (circled in red) need to be loosened. The lower right screw is hidden in the pic but is easy to get to on the right side of the wire bundle.



With the support bar removed and the junction box loosened the blower fan has room to wiggle out. Unplug the main (white) connector in the center of the fan and pull off the black ribbed tube where it enters the airbox. The blue relay doesn't need to be unplugged but the 8mm bolt (circled) needs to be removed. Remove the 3 equally spaced bolts holding the blower to the airbox and out she comes. The upper right bolt is tough to get to but there are a couple of options.



To get to this last bolt I started out using a ratcheting 8mm combination wrench which was tedious but worked.



After drawing blood with the wrench, I finished off the bolt removal with a 12" screwdriver passed through the opening created by loosening the white wire junction block. Much easier than ratcheting.



Fan Control Amplifier and Blower Fan removed. Assembly is the reverse of installation and will go much quicker now that you know where everything is located.



The unit on the right is the blower fan that was removed. The blades are full of caked-on dirt that adds weight and puts stress (amperage draw) on the blower motor and eventually burns up the amplifier. Similar to what a dying fuel pump can do to a new FPCU. The unit on the left is my cleaned up replacement. The replacement fan control amplifier won't last long if the fan blades aren't cleaned up at the same time.



The amp on the right is the failed unit. The cooling ribs are full of corrosion and, heat transfer is compromised and the internal darlington resistor overheated and died. The unit on the left is my spare that was cleaned up with wire brushes and bottle brushes. It's not the prettiest used part but it works fine and is a lot cheaper than new. A recent thread talked about rebuilding the amp (replacing the resistor?) so that will be one of my next projects.


Modified by goody94q45 at 12:34 PM 7/26/2009

[maxnix]

A write up commensurate with Tangalora's standards!

An Article it is!