Procedure: Repair ventilation fan speeds.

Originator: John Dziak, Electron-Meister, Owner of Silver '88 Supra NA July 10, ' 96

Problem: Fan ventilation switches would only work on med and hi speeds, (Or Similar)

Tools Needed:

- Medium sized Philips screw driver

- Fine sized needle nosed pliers

- Soldering iron and 60/40 rosin core solder

- Continuity Checker or Volt-Ohm Multimeter (VOM)

- Dremel Tool with Torpedo shaped Grinding Bit

- Clear quick drying lacquer

- Flashlight

Procedure:

1.  Under the glove box locate 3 screws holding a protective plastic panel. Screws are located just below glove box hinge area.

2.  Remove screws and take out protective panel.

3.  Look for a connector with 6 wires going to it.  It is located just about in the center of the glove box area about 8-9 inches (20 cm) above the floor board. This connect is fastened to one of the air plenum ducts under the dash.

4.  Locate a single screw to the left of the connector.  Remove it.

5.  Gently pull out the whole assemble from the air plenum.

6.  Disconnect the cable connector from the assembly.

7.  You will now be holding a small plastic block with male spade type connectors on one side and 5 wire coils on the side of the block inside of the air duct.

8.  The coil of wire which is the smallest, nearest the hole used for the fastening screw, is the "resistor" which controls the low fan setting. Check carefully, somewhere this coil is broken from thermal stress. Also notice that each coil has a dab of some hard white compound.  This is potting compound used to keep the coils from "vibrating" around and shorting out against each other.  Try not to break this stuff off if you can help it.

9.  Now you need to make a decision....

    - Use the fine pair of needle nose pliers to probe at the broken coil. If a large chunk of it breaks off repair may not be possible and you can buy a new resistor assembly from Toyota

or
    - Try to solder (connect) the two ends back together.

10. To repair the two ends:

    - Use Dremel tool and grinding bit to clean off ends of broken coil wire.  The wires I fixed were either insulated or had a black type of "oxidation" deposit on them. Don't be afraid to stretch out about 1 coil length of wire (about .5 inches/1 cm) and grasp it with the needle nose pliers while cleaning it up with the Dremel tool.  This wire is pretty flexible and can take the handling!

11.  Now for the slightly tricky part.  Line up both ends of the cleaned ends so that they are along side each other (in parallel).  Use the needled nosed pliers to twist the ends together with a 1 to 1.5 turn twist.  The cleaned-up, bare ends of each wire need to be touching.

     - I tried to do this by butting both ends together, but this arrangement was nearly impossible to solder.

12.  Heat up your soldering iron and place it under the twisted bare ends. Feed some rosin core solder into the twist until a large enough blob of wet solder is between the two twists, move the soldering iron away and let the joint cool.  Note, this wire doesn't seem to take solder real well, so you might need to try a couple of times!

13.  If you have either a continuity checker or a Volt-Ohm Multimeter (VOM) now is a good time to test the two connections that the resistor coil makes contact with.  On the VOM, set the Ohms range switch to its lowest setting (x1) and read the meter.   You
should getting a resistance reading of 1.5 - 2 ohms.  If you can't get a reading, check your connections and/or run a test probe over to the solder joint to see if everything is alright at that point. With the continuity checker, all you will be able to verify is if the connection is complete.


14.  If all connections are OK, I'd recommend that you use a clear enamel lacquer to seal/insulate the solder joint and any other "bare" spots on the resistance coil that the Dremel tool might have nicked.  This will make sure that nothing shorts out after the resistor assembly is placed back in the car.

15.  After the lacquer dries, use the needle nose pliers to reform the repaired ends into the shape of the original coil.  The whole thing needs to fit back into the air duct plenum!

16.  Repeat steps 1-6 in Reverse to put everything back together.

17.  FIGHT ANY URGES TO TRY OUT THE FIX BEFORE YOU HAVE THE COIL ASSEMBLY BACK IN THE AIR DUCT PLENUM. AIR BLOWING OVER THE COILS FROM THE FAN MOTOR ACTUALLY KEEPS THEM FROM OVERHEATING AND POSSIBLY BURNING UP.

Believe it or not, this repair job takes about 30-40 minutes tops!  I've had my repair working about 15 days and all seems to be fine.