Resolved 2015 Golf AC not working, condenser fan works when radiator commands it but not when AC commands it.

[EuroX]

Please do a resistance reading for each of the wires for the pressure switch.

 

[MrNomad105]

Thx for the reply. I'm 99% certain that pin 16 is correct. When I sliced into it at the G805 violet/blue wire and the J301 HVAC module connector, continuity ended. When I completed the external splice/bypass between G805 and J301 pin 16 to test the harness, continuity reestablished. The main problem seems to deals with BAR (IMHO). BAR reads lower than simple math computes it should be. BAR should be high side pressure divided by 14.7 but my BAR is always much lower. I've installed three G805 sensors and a fourth unit from a working Golf. All of them reported a BAR that is too low, does not compute. My best guess is the J301, the manual HVAC module, is defective. The Engine Adv Measuring Value says the FAN REQUEST FROM AC is 0%. If the HVAC isn't requesting condenser fan, it's never going to spin. The module which should issue that request is the J301.

Do u know of a way to reboot the J301 HVAC module? Set it back to factory default, like a PC Rom Bios?

Thx for the heads up on why CAN doesn't see the compressor. The compressor is not a module, ergo, it doesn't exist as source of information. It's a slave. I guess that option was left in there for other VW models.

I will get rid of 5F as u indicated, "tick it".

 

[NZDubNurd]

My best guess is the J301, the manual HVAC module, is defective.

It might be worth trying a used unit, but I'd be wary of spending too much - it's strange you do get changes to the reported pressure between the engine running, or not. It may be related to the increased voltage from the alternator running, but even that is a bit odd, considering that needs to be accounted for to get plausible readings. It's probably worth a try at this stage though.

 

[MrNomad105]

Very good idea! I can eliminate the impact the alt has on the circuit by connecting a bat charger while KO E Off. Meanwhile, I found a J301 on Ebay for $30 US. Worth a try. B here next week. I also ordered a blank connector that fits the G805. It's conceivable it's receiving 12- and 12+ but one of them could be insufficient due to corrosion. When the connector arrives, I will use bat+ and bat- and determine if the output is any different. For Christmas, I asked the wife for a scope. I will buy one that has a signal generator built into it so I can synthetically turn on the condenser fan and learn more how that operates. Thx for your help. I sincerely appreciate being able to discuss this with others.

 

[EuroX]

I honestly would be checking resistance of the wiring rather then going this far to isolate things. This is just my opinion. In any case let us know how you make out.

 

[MrNomad105]

Thx folks. I conducted those tests earlier but I sincerely appreciate the ideas and the feedback. Please, challenge my ideas.

I grafted an external wire to replace the violet/blue signal wire that runs thru the harness to the J301 HVAC module, T20d connector, pin 16. The result was the same. Bogus BAR. I tested G805 ground & G805 12+ with a test light. The test light creates a load whereas a volt meter simply measures, but the BAR was still incorrect. The 3 pin pigtail enroute thru Ebay will permit me to completely remove the existing wiring from the circuit. The replacement J301 enroute will replace the existing HVAC module. Conceivably, the J301 coming from a junkyard in Florida could have other problems but it's unlikely they will be the same.

My understanding of this operation is the J301 receives data from G805 and other sources and it sends an instruction to the ECM to turn on the fan. VCDS is telling me that J301 is NOT requesting fan, demand is 0%, so the ECM doesn't turn the fan on. Until I can get an accurate BAR, the HVAC is not going to activate the fan.

However, in order to actually drive the car and have AC, I figured out the following thru trial and error. If u cut/open the signal wire on the fan module, the fan assumes an emergency condition and spins at high speed. Cutting the signal wire also creates 0480 DTC which I clear before tests. With the fan signal wire cut/open, the fan cools the condensor and the engine quite nicely. To turn off the fan when I arrive at my destination, I reconnect the fan signal wire. I installed a SPST toggle switch to make this easy. The fan signal wire uses a PWM signal to regulate the speed of the fan. I have observed that when the engine gets warm, with the signal wire properly connected & the DTC cleared, the radiator temp sensor will turn on the fan. I connected a voltmeter with a long wire hanging out the window so I could observe the voltage change. As the engine gets warmer, the DUTY CYCLE changes and the fan speed increases. Of course, a volt meter can only tell me the average voltage, not the high/low or duration. If all else fails, I may install a variable signal generator in the cabin, wired to the fan signal wire, that instructs the fan to run at 50% which is all that's needed. I hope to avoid that task and prefer to solve the problem but that's why the wife agreed I need a scope.

I love this car. It's fast, quiet and practical. I haul all kinds of stuff in the hatchback so I intend to keep it and fix it. Meanwhile, it's giving me an education, an EE degree. Hahahaha. Thx folks.

 

[MrNomad105]

Ok, I am officially stumped. I replaced the J301 HVAC module, input the codes from the old J301, but there was no change to BAR and the fan never went on. In retrospect, I evac and filled the system with 500 grams, eliminated the wiring to the G805, tried 4 different G805 sensors including one from a working Golf, and replaced the G805 to J301 wiring. To make this car more usable, I ordered a signal generator I will graft into the fan signal wire which will send enough voltage and duration to spin the fan at half speed.

Ideas welcome.

 

[EuroX]

Was an adaption performed on the module? In some instances hvac and vin inside the unit must match in order for the ac to work. Normally fault code stored for mismatched vin iirc. Also if possible please probide location of G805 if you have a picture.

 

[MrNomad105]

No, I simply replaced the long code. No fault codes found. G805 located on right front fender, passenger side (my Golf is left hand drive, US). The replacement J301 has a different Workshop code, Importer and Equipt. Under HVAC Basic Settings, I find RESETTING OF ALL ADAPTATION VALUES and RESETTING ALL ADAPTATIONS and others. Pls point me to the correct adaptation procedure(s) for compressor and J301.

 

[EuroX]

Compressor adaption should only be carried out if compressor is replaced. It's a run in procedure basically. I would check compressor shut off condition at this point see if its changed.

 

[MrNomad105]

Got it. I didn't replace the compressor so please discuss which adaptation is required for J301.

 

[EuroX]

Got it. I didn't replace the compressor so please discuss which adaptation is required for J301.

Sorry reading my noted compressor run in required for j301 replacement. My bad.

"AC Compressor First Run-In" Steps:
Start engine and allow it to Idle.
Adapt flap end stops first. Then run the following:


[Basic Settings - 04]
Select "Compressor Run In; Automatic Start" from the drop-down list.
[Go!]

It will show completed, but wait 120 sec (2 Min) and observe the flashing A/C button light on the HVAC panel.

After the Basic Settings has completed, the A/C light will quit flashing and the fault code will clear.

[Stop]
Note:*If Basic Settings reports Error the module may need to see an Adaptation change before this can be completed. Go to Adaptation and change "Driving time for compressor run in" from 120 -to- 120 and save it followed by repeating the entire procedure.

 

[MrNomad105]

Thank you.

U said: "Adapt flap end stops first." It was successful.

Next step: "IDE02259-Compressor break-in: automatic start" That produced an error: "ERROR CONDITIONS NOT CORRECT OR REQUEST SEQUENCE ERROR"

So I went into BASIC SETTINGS and found "IDE03176-Duration of compressor run in". The value was 0 so I set it to 120 per your suggestion. It accepted that value. I waited 2 minutes.

Went back into: [Basic Settings - 04]
Select "Compressor Run In; Automatic Start" from the drop-down list.
[Go!]

It repeated the former error: ERROR CONDITIONS NOT CORRECT OR REQUEST SEQUENCE ERROR

Question: Does it matter if the AC is on or off?

I shut the engine, waited, restarted, repeated procedure, "Select "Compressor Run In; Automatic Start" but the same error appeared.

Seems like we are very close. Thx.

 

[MrNomad105]

Sad to say, I made it worse.

Given that 120 duration didn't change anything, I extended the procedure to 240s.

"Adapt flap end stops first." It was successful.

Select "Compressor Run In; Automatic Start" from the drop-down list. [Go!] It worked.

But now compressor does not run, no fan, warm air, AC lite on the J301 blinks on/off. Suggestions welcome.

 

[EuroX]

ac button is blinking? if so then it should be doing the compressor run in iirc

 

[MrNomad105]

It's 5 hours later. The AC lite is still blinking when KOER. No compressor, nor fan. Next idea?

 

[EuroX]

Trying changing the value again to 120 and let it run for 2 minutes and see what it does.

 

[MrNomad105]

Thx. You have been very patient and helpful.
I tried that last nite and the light never stopped blinking. I also got a B109E code so this morning I reinstalled the original J301 and followed the procedure again.

I set the DURATION to 120s even tho it was 120. Set the flap limits, success, tried to do use Compressor Automatic Start, refused.

Subsequently, here's what I tried with 08 Auto HVAC this morning.

I used AC compressor activation and the compressor ran, air got cool. That was encouraging.

Did a full scan:
Address 08: Auto HVAC (J301) Labels:| 5G0-907-426.clb
1 Fault Found, 524545 AC Compressor First Run In, B109E - Not Performed. (But we already knew this).

also

Address 19: CAN Gateway (J533) Labels:| 5Q0-907-530-V1.clb
1 Fault Found:
66304 - Databus
U1124 00 [009] - Additional Installations Detected
[Mehrverbau CAN]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 168
Mileage: 155343 km
Date: 2023.09.21
Time: 06:44:33

Terminal 30 power supply: 13.7 V
Terminal 15: On

For the duration of this project, is there a procedure to turn off the annoying beep that comes from an open door?

 

[EuroX]

Open door gong probably and adaption of coding of the dash IIRC. I would say we need to figure out why it won't run the ac compressor run in.

 

[MrNomad105]

Thx again. I am open to suggestion how we approach this.