The Dispatch | Expert | Scudo Hub

From the diagrams I've found, the slider just sends a variable voltage  to the Driver
circuit mounted on/near the fan motor housing
This is where the power is controlled to dictate fan speed
If the diagrams I have are to be trusted it controls the ground path current.

I haven't looked at mine so can only make guesses and assumptions
but would probably start by checking the signal voltage
to the controller on what my diagram says is green wire.

If I got no voltage I'd suspect the slider which would be relatively easy to hack
or workaround with an external potentiometer.
If I got a varying voltage, I'd suspect the controller which I can only guess is either a PWM device or maybe just a simple power amp
The motor itself may be knackered for all we know so a temporary direct control hack would help decide what action to take next.

I see it went for £320

While you're working through getting it up and running again
I'll suggest you put the vehicle details, especially engine type in your signature
DW8/XUD/1.9D/1.9 TD etc to help narrow the focus on what type you're dealing with.

if you suspect glow plugs, voltage supply from the relay is easy to test for but you'll need to isolate each one and do
careful resistance tests in situ to determine if they're OK or not.
A pic or pics of the engine would help too

AFAIK the 1.9's are indirect injection lumps? so bad or non working glow plugs will make them
very hard to start from cold

Do RCZ owners get pissed of when folk like me say "Hmm, looks an Audi TT dont it?" 

Anyway as I got proficiency badge in the cubs, I'd say the heater core is blocked or there is an airlock
air bleeding/checking would be the first thing to check of course
Next be sure you have the heater inlet and outlet correctly identified
the heater core is usually supplied from the engine within the thermostat zone so it can circulate coolant
through the heater whether the thermostat is open or shut for faster warm up.
the outlet on my van runs to the header tank so pre thermostat.

When my core was blocked, the supply hose would get hot but the outlet back to the header cool or warmish at best.
I found using Rad flush and back flushing was partially helpful, but it was only when I fitted a new core that it got proper toasty.
Your RCZ being a 2010 car suggests its quite feasible for it to have accumulated a build up of crap in the last 15 years.

Out of interest I did quick Ebay search and this motor seems to fit many similar vehicles
and it fits the 1.9D 1.9TD and 2.0 HDI
(inc 98 dispatch)
I see no mention of teeth and pitch
( aint nobody got time for that )

https://www.ebay.co.uk/itm/115520170512?

Another test I'd do while its on the bench is by pass the solenoid and
apply the battery power directly to the motor terminal.
You have to be careful not to short the lead on the case of course so
some masking tape or similar can be used as a temporary insulator.
if it spins up like a good un with lots of torque reaction then the problem could
in the solenoid contacts but how serviceable they are is unknown.
if its still poor, the problem lies within the motor and apart from brushes and commutator, there's not much you can do unless you spot a bad solder joint or ground terminal.

It's always hard work to diagnose at a distance without clear precise info but I have thoughts and questions

The warning light on may suggest its getting enough current to excite
but you need to check for a voltage at the D+ terminal on the alternator when you turn the ignition on
to be sure.
Have you fitted an externally regulated ( smart) alternator to a vehicle wired to use an internally regulated type?
Have any of the mods you've done affected the function of the vans charging system and possibly caused the old
unit to fail and negatively affect the new one?

Like most of us, I've bitten in the ass by assumptions too many times
which has taught me to 'Test don't guess'
I'd whip it out, do some checks and bench test it.
If its 'smart' one, change it for a 'dumb' one suitable for the vehicle
If it's 'dumb' and works on the bench, the fault is in the van wiring

A 'minor kick ' is somewhat concerning, there should be a very definite and strong torque reaction when energised
I tested a motorbike one recently and even that had to be firmly held in place.
Chinese stuff can be good to very poor, I'd have it apart to check the brushes and commutator
plus the heavy duty contacts for arcing damage that will restrict current flow.
if the brushes look ok but its all sooty, get some brake or carb cleaner in there to rinse it all out

Definitely, an alloy head has good thermal conduction but depends on a good flow of coolant to help
dissipate the heat from combustion which keeps temps in a range it can cope with.
A poor flow of coolant can allow the head to overheat and eventually cause it to distort/leak.

I find Gumtree to be useful and free to and bought this van from there
It has its eejits the same as Facebook of course
I will often insist on 'calls only' and ignore texts as this can help sort out the
time wasters from serious buyers.
You may be able to flog a few bits off like the seats before scrapping it to make an extra few bob
If you weren't in 'Auld Reekie' and me in Bristol and you were scrapping/parting it out i may have been after those seats as they do look nice, but those and the other upgrades may help you find someone interested in a project your side of the Pentland  HIlls or borders even.

BTW Gumtree is pretty much nationwide
I've flogged stuff I thought would only be advertised locally and had folk from all over the place contacting me.
I was selling a wee scooty and had a lad near Glasgow asking about it.
I'd avoid Freeads.co.uk site if I was you, I tried it and it was a waste of time

1 Firmware updating.
2 The option to connect it to a lappy/USB port if BT wasn't available.
3 If they cheaped out the ftdi ic what else might they have cheaped out on?
None of these devices will be top notch stuff for the price but should have at least the basic functionality
stated in the descriptions.

The software looks pretty useful though, I've only installed Delphi so far and it appears to run OK on win 10/64
based on a quick test run but will have a play with Autocoms later
I've collected quite a library of OBD software collected from various sources and will run few on my air gapped lappy
I have a few simple VCIs to play with but hoped the Delphi knock off would let me get more in depth access.

In case yer wonderin....
basically an FTDI IC is a common interface that converts signals from a high speed USB bus to levels processors can handle.

if you want get in to UARTS RS232 TTL I2C etc, n shit look it up