1993 Toyota Previa has heater problem. replaced resistor, relay, and a new blower motor. my rear heat doesn't work and neither does my air conditioner.

SOURCE: Blower motor has only low speed

You may need to get the correct resistor, as they are designed to only allow so much amperage to go through them. If it is getting very hot it is runnig to many amps through it. It will eventually blow and you will need to replace it anyway.

SOURCE: I can't find the fuel pump relay in a 1993 Toyota

The fuel pump relay is always one of these two places, either under the steering colum to the left of the break pedal in the fuse/relay box or it would be under the hood of the car on the driver side also in a fuse/relay box.

SOURCE: Replacing heater fan motor in a Toyota Previa

Removal & Installation It may be necessary to remove the upper radiator shroud to perform this procedure.

1. Open and support the hood.
   
2. Disconnect the negative battery cable and wait at least 90 seconds to proceed working on the vehicle.
   
3. Disconnect the power steering and coolant reservoirs.
   

Disconnect the coolant reservoir

4. Disconnect the coolant reservoir and power steering brackets from the side of the heating unit box.


Remove the coolant reservoir bracket from the side of the heater unit


Separate the power steering reservoir bracket from the side of the unit also

5. Remove the two bolts that attach the upper and lower portion of the heater box. 6. Disconnect the control cable on the side of the heater unit box.

Disconnect the control cable on the drivers side of the unit

7. Remove the eight nuts retaining the unit.


Remove the nuts (8) from around the heater unit


There are 4 nuts on each side of the unit

8. Disconnect the heater control valve bracket from the heater box.

9. Separate the top of the control box from the bottom.


Separate the upper case from the lower

SOURCE: PREVIA 1992 NO HEAT

If your Previa's low/medium speeds on the blower (ac/heat fan) have stopped working, but the high speed works, you most likely have a problem with your blower motor resistor. Here's how to access the resistor. These directions may be slightly incorrect since I finished this procedure about an hour ago and I'm typing this from memory. But they should get the job done. It took me about 30-40 minutes to do this from start to finish:

Remove cabin air intake duct (two philips screws)
Remove one bolt holding antifreeze reservoir in place, move reservoir aside.
Remove two bolts holding brake fluid reservoir in place, move reservoir aside.
Unsnap recirculate/fresh selector cable from blower housing (on vehicle-left side of housing)
Remove angled metal arm from vehicle-right side of blower housing (attaches to firewall with nut and to housing with bolt).
Remove two bolts (at vehicle-front of housing) that hold the upper and lower blower housings together.
Remove nuts on firewall holding upper blower housing in place, and begin to work upper housing out of vehicle, disconnecting the 4 electrical connectors as needed (2 connectors are on top and 2 are down beneath the blower housing).
Remove nuts on firewall holding lower blower housing in place, and remove lower blower housing from vehicle

Look on the lower blower housing, on the side which was facing the firewall, and you'll see a white ceramic block (approx 2-3 inches long). This is the blower motor resistor. There are 2 contacts on the resistor that should be joined by a springy curved band. If the band isn't bridging the two contacts, it's likely that the soldier has melted/broken, and this is what's causing the low/med speeds to not work. Solder the band back in place and this should correct the problem (it did for me).

SOURCE: have a 1993 toyota pickup 4 cyl heater blower

Hi!
To find out if your problem is the blower motor or the blower resistor or switch perform the following tests.
BLOWER RESISTOR

• Remove resistor from vehicle or disconnect resistor wiring.
• Using an ohmmeter, ensure continuity exists between blower resistor terminals No. 1 and 4. See Fig.
• If continuity is not as specified, replace resistor.

BLOWER SPEED CONTROL SWITCH

Switch Position (1) Continuity Between Terminal No.

1. OFF (1)
2. LO 5 & 6
3. (D) (2) 1, 5 & 6
4. (D) (3) 2, 5 & 6
5. HI 5, 6 & 8

(1) With switch in any position, continuity should exist between terminals No. 3 and 4 for heater control illumination. With switch in OFF position, continuity should not exist between any other terminals. (2) Circle (D) closest to LO position. (3) Circle (D) closest to HI position.


HEATER RELAY

• Remove heater relay.
• Using an ohmmeter, ensure continuity exists between heater relay terminals No. 1 and 3, and between terminals No. 2 and 4.
• Ensure continuity does not exist between terminals No. 4 and 5. If continuity is not as specified, replace relay.
• Ground terminal No. 3, and apply battery voltage to terminal No. 1. Ensure continuity exists between terminals No. 4 and 5.
• If continuity is not as specified, replace relay.

BLOWER MOTOR

• Disconnect blower motor wiring harness connector.
• Apply battery voltage to motor side of connector. Motor should operate smoothly.
• If motor operation is not smooth, replace motor.

BLOWER MOTOR REMOVAL & INSTALLATION

1. Disconnect negative battery cable.
2. Remove glove box, if necessary.
3. Disconnect blower motor and resistor connectors.
4. Remove 3 screws and blower motor.
5. To install, reverse removal procedure. See Fig.

HEATER BLOWER WIRING DIAGRAM

Heater Relay is located on the Relay Block, Front Right Side Of Engine Compartment
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