BKC engine cooling problems - radiator fan and Air Conditioning

[Marcouscous]

I was hoping someone would be able to give me some guidance on this as I can't figure out what's going on!

I have a 2005 VW Touran 1.9tdi PD105 (pdi) BKC

Last summer the Air Conditioning in it died suddenly. There were no other problems and I couldn't afford to fix it. So I left it. This summer, I have had enough of sweating so decided I would get it fixed. I've only got a basic OBDII code reader, so I borrowed my neighbours fancier one. It said that the AC low pressure sensor was dodgy, so I replaced it with a new one as it was only ~£10. It fixed the AC!
But... I now have a load of other issues.

The symptom is that the radiator fan is running on full blast all the time - including when the engine is cold and only the ignition is on (not the engine). It spins up to full blast for 30 secs, then slows right down before spinning up again. It does not stop so long as the ignition is on. I have done the obvious thing of turning the AC off as I know this would cause the radiator fan to spin up. As a result the engine struggles to get up to temperature on cooler summer days, and the engine temperature does drop down from 90degC on slower roads. The engine does not overheat.

My neighbours code reader had also given some other codes which looked related to this problem (my code reader also gave the same codes but without as much detail). They were:

• 18049 - Please check DTC memory of A/C ECU P1641
• 18617 - Coolant Temp Sensor on Radiator Outlet (G83) problem
• 16502 - Engine Coolant Temp Sensor (G62): Signal too High
• 01314 - Engine Control Module: No Communications

Because of these I decided to replace the radiator temp sensor (G83) and engine temp sensor (G62) - they were cheap parts. To no luck.

Then I thought that the new AC pressure sensor must be dodgy, which I thought was proven as when I disconnected the wires into AC pressure sensor, the fan doesn't turn on when on ignition only, and the AC stops working. The new one arrived and I just fitted it but the problems still persist. I ran the codes again, this time on my code reader and it gave the following:

• 16502 - Engine Coolant Temp Sensor (G62): Signal too High
• 19558 - Motor for Intake Manifold Flap (V157): No Signal
• 19557 - Motor for Intake Manifold Flap (V157): Open or Short to Ground

I cannot find any obviously blown fuses or relays, and I've just had a look at the intake manifold flap, and it's not jammed. And the G62 code hasn't disappeared!
What's going on?!

Thanks, Marcus

tldr: AC pressure sensor is causing radiator fan to spin on full blast and throwing up loads of codes.

 

[Marcouscous]

Not resolved, but a further update which may help with diagnosis.
Fuse 8 in the fuse box in the engine bay is related to this issue. When I replaced it with a new fuse it did not stop the fan from running. However when I tried running it without the fuse the fan did not run. I'm starting to suspect it may be wiring somewhere but I have no idea where to look.

 

[wonneber]

I'm confused a bit.
How would the fan work without the fuse for it?

 

[Marcouscous]

Sorry for the confusion. The fan doesn't work when the fuse is not there. Which I guess would be normal.

An update: I've just been out for a quick drive and scanned the codes again. This time it has:

• 19558 - Motor for Intake Manifold Flap (V157): No Signal
• 19557 - Motor for Intake Manifold Flap (V157): Open or Short to Ground
• 17075 - Fan 1 short circuit: Short to Ground.

With the new code all things now seem to suggest that the fan control module is to blame, as it seems to be the common factor in the scans (the fan keeps spinning) as both the AC and motor for intake manifold flap are on the same fuse/circuit as the radiator fan.
I believe I need to replace the whole fan. Is this correct?
Would this also mean that the coolant temp sensors were a different problem, or were they related because the fan was sending faulty signals?
TIA, Marcus