Hitachi zx70 heater motor resistor

[Vinpetrol]

Does anyone know where the heater blower resistor is on a zx70 hitachi ? The fans stopped blowing on my one this morning but I can’t find out where the resistor is .
Or any ideas what else to check ? I’ve tried all the fuses and they are good and the unit in the dash has power and is all working just no fan blowing at any speed

 

[Gecko]

just no fan blowing at any speed

The resistor is used at all speeds except Max (where it is bypassed).
If the fan is not working at any speed, it's probably something else.

 

[Vinpetrol]

The resistor is used at all speeds except Max (where it is bypassed).
If the fan is not working at any speed, it's probably something else.

Any idea what else it could be ? I did read somewhere that someone had same problem and he was advised that it would be resistor but frustratingly never commented on how he sorted it

 

[V8Druid]

would a modern machine (how old is the 'Tachi @Vinpetrol ) still use a resistor, over an electronic speed controller for the motor??
as said, if it were a resistor it should be bypassed at full chat, unless the motor itself has failed, where as a 'black box' failure would be just that - a complete failure

 

[Gecko]

Can't find a (free) manual, so just flying blind.
Blower motors pull a surprisingly high current, so I'd check the fuse again and the relay if it uses one.
How old is it?

 

[Vinpetrol]

Can't find a (free) manual, so just flying blind.
Blower motors pull a surprisingly high current, so I'd check the fuse again and the relay if it uses one.
How old is it?

It’s a 2008 machine . 5K hours

 

[Vinpetrol]

would a modern machine (how old is the 'Tachi @Vinpetrol ) still use a resistor, over an electronic speed controller for the motor??
as said, if it were a resistor it should be bypassed at full chat, unless the motor itself has failed, where as a 'black box' failure would be just that - a complete failure

It has a digital control incorporating air con and heating . No dials , it’s all digital .

 

[V8Druid]

It has a digital control incorporating air con and heating . No dials , it’s all digital .

sounds like a plug in is gonna be your only option for a diagnosis Vin

 

[Vinpetrol]

It has a digital control incorporating air con and heating . No dials , it’s all digital .

This is exactly the same

 

[Gecko]

It's 2026 now, do we have to start calling it a Landcros yet?

No dials , it’s all digital .

That up'd the chance of there being a relay, so that's a plus.

 

[Vinpetrol]

sounds like a plug in is gonna be your only option for a diagnosis Vin

I don’t know anyone who has software reader for Hitachi’s.
As the heater controls are the same across the range I was hoping for a steer from anyone who’s had an issue with theirs on any other models that use the same controls and if so what parts are the likeliest to play up

 

[Vinpetrol]

It's 2026 now, do we have to start calling it a Landcros yet?

That up's the chance of there being a relay, so that's a plus.

I’ve been driving Hitachi’s since the first ones in the 80s there’s no chance of me calling them landcross when in my head a Doosan is still a daewoo and nissan is still a Datsun a starburst is still an opal fruit and don’t get me started on snickers

 

[Vinpetrol]

It's 2026 now, do we have to start calling it a Landcros yet?

That up's the chance of there being a relay, so that's a plus.

All the lights and controls and display are working normally on the heater control unit .
Just the fan doesn’t kick in . Could that still be relay ?

 

[Gecko]

All the lights and controls and display are working normally on the heater control unit .
Just the fan doesn’t kick in . Could that still be relay ?

Yes.
Sounds like the smarts are all good, so a relay or motor earth is still high on the list.

 

[Vinpetrol]

This is the wiring drawing . (And other stuff I can’t separate )

 

[Gecko]

That's progress!

There are two relevant fuses:
The 5A powers the control box
the 20A powers the blower motor

The Off Relay is the common factor

I'd be checking those and swapping if there is any doubt.

 

[Vinpetrol]

That's progress!

There are two relevant fuses:
The 5A powers the control box
the 20A powers the blower motor
View attachment 79065


The Off Relay is the common factor

View attachment 79066

I'd be checking those and swapping if there is any doubt.

Thanks for this , I will report back

 

[Vinpetrol]

Back at this today .
This may be beyond my electrical ability which is not the finest at the best of times but I’m having a bash because the machine is way over the west miles from auto sparky just now.
I managed to get in about the wiring a bit without taking the whole levers off and floor out . I can see 3 relays that are all the same . I’ve swapped them about to no avail . I checked the connectors and I’m getting 28v with engine running at the one that has screwdriver pointing to it . Other than that I’ve not got anywhere .

 

[Vinpetrol]

I had a bit of a breakthrough !
I found what I think was the power lead running to the heater motor . It was live 28.8v with engine running so I thought that the motor was goosed . When I exposed the motor wiring I came across 2 filters that filter the air going through the motor . They were choked .

I then made a note to get 2 replacements and then gave them a good clean out for now and put it back together .
Lo and behold , It then started working !
I wondered if the heater motor might have a cutout if it overheats and it might of kicked in with lack of through flow of air . Either way it’s running now so I know the motor isn’t goosed if it plays up again .

 

[V8Druid]

I had a bit of a breakthrough !
I found what I think was the power lead running to the heater motor . It was live 28.8v with engine running so I thought that the motor was goosed . When I exposed the motor wiring I came across 2 filters that filter the air going through the motor . They were choked . View attachment 79656View attachment 79657
I then made a note to get 2 replacements and then gave them a good clean out for now and put it back together .
Lo and behold , It then started working !
I wondered if the heater motor might have a cutout if it overheats and it might of kicked in with lack of through flow of air . Either way it’s running now so I know the motor isn’t goosed if it plays up again .

those filters may need entering into the Guinness Book ... for longevity Vin .... ... deffo not gonna cut it on extended performance life though