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The air conditioning (A/C) is not working?

Tiny
RAJ SUNDAR
  • MEMBER
  • 2005 VOLKSWAGEN GOLF
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
I have an automatic Golf FSI 2005. I'm not sure if it has a 1.6L or 2.0L engine, but since it’s not turbocharged, I assume it has a 1.6L engine.

The air conditioning (A/C) is not working. I’m uncertain whether the compressor has a clutch because there is a control valve connected to the back of the compressor with two wires, and I don't see any other wiring connections. When I turn on the ignition switch, I measure around 5V on one of the wires. I can see the high-side pressure switch, but I cannot locate the low-side switch.

There was very little refrigerant gas in the system. I safely evacuated and recharged it with Hychill Minus 30 after confirming there were no leaks during the vacuum process. However, the compressor did not engage, and I observed 80 psi on both the high and low sides. Additionally, the refrigerant paused halfway while entering the system.

I would greatly appreciate your assistance in troubleshooting the issue. Additionally, please provide the wiring diagram for the A/C, as well as the locations of the relays and fuses.
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Monday, November 18th, 2024 AT 1:04 PM

19 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Yes, if the system does not run it can't be filled completely. It shows this car having an external compressor clutch? Please check the diagrams below and confirm. Also, here is a guide to help us as well:

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Here are the A/C system wiring diagrams which show the fuses that you need to check with the key on:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.
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Monday, November 18th, 2024 AT 5:07 PM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Thank you, Ken, for your reply and the diagram.

I noticed that the compressor control valve is not included in the diagram, although the clutch is present. I couldn't find any wiring for the clutch if it exists. I believe my compressor is a clutch less variable displacement piston type with a solenoid valve at the back. Please take a look at the attached picture of the label on the compressor.

It seems that the diagram is for the 2.0L models. I would greatly appreciate it if you could provide me with a diagram for the 1.6L FSI model.

Additionally, the A/C fan is not turning on when both the A/C switch and the blower are activated.

I look forward to your prompt reply. Thank you!
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Tuesday, November 19th, 2024 AT 4:44 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Can you please upload an image of the front of the compressor? I checked the 2006 diesel model as well and it says it has a clutch?
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Tuesday, November 19th, 2024 AT 10:18 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Please see the attached pictures. The first image shows the existing compressor, while the others display a new compressor compatible with part number 1K0 820 803 L.
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Tuesday, November 19th, 2024 AT 9:03 PM
Tiny
RAJ SUNDAR
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  • 42 POSTS
I see a label with "BLX" on the timing cover. If that refers to the engine, then this model has a capacity of 2 liters.
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Tuesday, November 19th, 2024 AT 9:07 PM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
It is now confirmed that the engine is a 2L FSI, as per a label inside the boot.
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Tuesday, November 19th, 2024 AT 10:12 PM
Tiny
KEN L
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Yep, this is an internal valve compressor. Can I ask if this is a euro car?
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Thursday, November 21st, 2024 AT 10:10 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Yes, Ken, this is a European car designed for Australia. Unlike Japanese cars, the indicator switch is to the left of the steering wheel, while the wiper switch is on the right. It is a right-hand drive vehicle.
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Thursday, November 21st, 2024 AT 5:37 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Yep, it makes sense. No worries let's connect an AC gauge set on the high and low side to see if the system kicks on or not.

This video can help you:

https://www.youtube.com/watch?v=4EqdrBVb0sY&t

Please let me know what the pressure is with the system on full cold. Also, in the fuse panel images it seems like many fuses are missing?
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Friday, November 22nd, 2024 AT 12:08 PM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Thanks, Ken, for your reply.

I observed a pressure of 80 psi on both the high and low sides of the system. Additionally, the refrigerant paused halfway while entering the system because the compressor didn't kick on. I measured the voltage at the high-pressure sender connector and found a supply of 12V. The voltage at the compressor regulate valve connector is 8V. I suspect that this valve may be faulty. I evacuated the refrigerant to remove the valve from the compressor.

Is there a way to test this solenoid valve? Please let me know.
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Saturday, November 23rd, 2024 AT 4:38 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Please see the image of the valve.
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Saturday, November 23rd, 2024 AT 4:43 AM
Tiny
KEN L
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How many wires go into the valve?
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Saturday, November 23rd, 2024 AT 9:49 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Two wires.
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Saturday, November 23rd, 2024 AT 4:24 PM
Tiny
KEN L
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You should be able to put 12 volts (power and ground) to it and hear it click. Let me know.
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Sunday, November 24th, 2024 AT 11:07 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
I have detached the compressor from the engine, but the hoses are still connected. I performed a bench test on the solenoid, and it clicks when 12 volts are applied and shows a resistance of 11 ohms.

I can feel air flowing out when I blow into the valve, and even with 12 volts applied, I can still hear air escaping, but not as strongly as before. I suspect that the valve is not closing properly fully.
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Sunday, November 24th, 2024 AT 6:38 PM
Tiny
KEN L
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Yep, you can be right about that but the valve probably does not close all the way, it controls the flow of the refrigerant not to close of the compressor completely.
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Monday, November 25th, 2024 AT 9:24 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
Can I rule out a faulty valve and troubleshoot the smaller fan behind the radiator, which I believe is meant for the air conditioning, since it doesn't spin when the AC switch is on?
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Monday, November 25th, 2024 AT 10:34 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Yes that should come on with the AC, did you go over the guide I posted in the first response?
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Tuesday, November 26th, 2024 AT 10:30 AM
Tiny
RAJ SUNDAR
  • MEMBER
  • 42 POSTS
I bench-tested the radiator fans. When I applied 12 volts to the red and black wires with the brown wire grounded, both fans started spinning. If I grounded the green wire as well, the fans continued to spin.

However, when I connected the fans to the vehicle, they did not spin. I disconnected the connectors and made the connections as shown in the picture below, but there was still no movement. Interestingly, when I disconnected the green wire, both fans began to spin again and stopped once the green wire was reconnected.

In the vehicle's wiring harness, the red wire has 12 volts at all times. The black wire has 12 volts only when the ignition switch is on, regardless of whether the AC switch is on or off. I also noticed that the 458 relay is hot.

Doesn’t the green wire get disconnected somewhere else when the AC switch is turned on? Can I conclude that the fans and the fan control unit are functioning properly?

Do you think the problem lies within the AC control unit?
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Thursday, November 28th, 2024 AT 10:05 PM

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