Avensis 98 Heater Blower Not Working.

[gavjbrown]

Hi heater blower has stopped working on all speeds on our 98 Avensis.

Has anyone a wiring diagram or know of any common faults.

On testing the 2 wires that go to the motor - one becomes a constant +12v when the switched from the off posistion and stays the same throughout the speeds.

the other wire is dead.

Thanks Gav

[Q.S.]

Hi heater blower has stopped working on all speeds on our 98 Avensis.

Has anyone a wiring diagram or know of any common faults.

On testing the 2 wires that go to the motor - one becomes a constant +12v when the switched from the off posistion and stays the same throughout the speeds.

the other wire is dead.

Thanks Gav

You say the other is 'dead', are you sure? have you tested it for -ve?

One wire is +ve, one is -ve, the speeds are accomplished by resistors, (usually in the +ve side) that reduce the current flow to control the motor speed.

Are you testing at the actual motor? if not, you may be testing before the resistor pack. Try a test light on the wires directly at the motor.

Resistor packs are a fairly common fault on heater motors but usually the full speed works as this bypasses the resistors with a full flow feed.

[gavjbrown]

Hi Q.S, Yes I was testing the connector that goes into the motor.

One wire is a constant 12v positive as soon as the blower swith is moved off the OFF posistion and doesnt change when going through the speeds. So I suspect the speeds are controlled by the -ve side.

With a test light to the car body One wire lights the testlight.

With a test light connected to both wire nothing happens.

So looks like the problem is With the -ve side. I was hoping someome may have the wiring diagram so I could follow it through.

[marama32]

Hi,

Ihad a similar experience with mine. replaced the heater control unit & everything worked fine after that. I got it off eBay for less than £20 used.

There is one on eBay for your model at £40 including delivery. You may get it cheaper at your local breakers though.

http://cgi.ebay.co.uk/TOYOTA-AVENSIS-HEATE...id=p3286.c0.m14

Cheers,

Marv

[Q.S.]

Hi Q.S, Yes I was testing the connector that goes into the motor.

One wire is a constant 12v positive as soon as the blower swith is moved off the OFF posistion and doesnt change when going through the speeds. So I suspect the speeds are controlled by the -ve side.

With a test light to the car body One wire lights the testlight.

With a test light connected to both wire nothing happens.

So looks like the problem is With the -ve side. I was hoping someome may have the wiring diagram so I could follow it through.

Try putting a negative onto the dead wire terminal and see what happens when you switch on the heater blower. If the resistor pack is on the neg side you will get full speed all the time. If the resistor pack is on the pos side, it should work as normal and it has simply lost the earth to the dead wire.

P.S. sometimes the resistor pack is situated inside the heater casing in the airflow to keep it cool. That's why I asked if you were testing at the motor direct. If the connector is outside the heater box, the resistor pack could be between there and the motor.

[gavjbrown]

Hi Q.S just got back from looking at it just now. The problem was caused by the connector that had worked its way out of the resistor. (located near left foot on drivers side)

Putting an earth to the dead wire ran the fan at full speed.

Thanks Gav

[Q.S.]

Hi Q.S just got back from looking at it just now. The problem was caused by the connector that had worked its way out of the resistor. (located near left foot on drivers side)

Putting an earth to the dead wire ran the fan at full speed.

Thanks Gav

That's a good result then Gav. ;)