The circuit for activating the A/C Compressor clutch has the high pressure switch wired in. If the system pressure is too high or the switch is faulty, you have no continuity thus no compressor clutch.

The compressor clutch solenoid could also be bad, but that's highly unlikely. Grab a digital volt meter to see if you're getting 12V to the clutch solenoid while the A/C is on (after the 8-10 second delay). If you have 12V, check continuity (harness connector must be unplugged) of the compressor solenoid (not sure of the clutch solenoid resistance but it should be higher than 0 ohms).

Even after 15 years...I still despise that 8-10 second compressor clutch activation delay "feature".

 

Thanks for the reply ! Where do I take the voltage and continuity measurements? At the compressor itself? (Is there a connector there?) Or at the 184 relay?

 

The fact that your car stutters makes me think it could be the compressor itself. Try and spin the compressor over by hand with the car off and see if it will move freely just by grabbing the clutch and turning it.

 

Okay, good point. I checked it and it is able to move with little resistance. The clutch is just not engaging at all.

 

The first click you're hearing is the coolant fan low speed relay. It runs whenever the A/C is on and comes on immediately.

The 384 relay, which controls the compressor clutch, has a time delay built-in and thus doesn't close for several seconds (10 seconds in your case).

There is a wire between the 384 relay and the ECM, but I don't know its function--it might tell the ECM to anticipate the compressor load; if so, that would explain the engine stutter, even if your clutch isn't engaging.

The 384 relay is known for cracking of the very large solder joints, the ones that carry the A/C clutch current (those sometimes causes intermittent trouble, too). Did you look for that when you had it open?

 

Thank you. I checked and what you said makes sense. When I turn on the A/C, the coolant fan does come on immediately.

Yes, I did carefully check all solder joints when I had the 384 relay out.

Tomorrow, I will check the voltage at the clutch and the solenoid continuity, as suggested by Electron Man.

Thank you again !

 

This YouTube video really cleared things up for me. It illustrates the basic operation of a generic automotive A/C compressor clutch:

 

I did the recommended tests, and am 100% certain that the clutch solenoid coil has an open circuit. Just to be sure that there was no open circuit in the exterior wiring, I stuck a needle through the wire insulation where the leads go into the clutch coil, and tested again from those points.

So I just ordered a new compressor, accumulator, orifice tube, and O-rings.

Your advice, please:

1) For a 2003 V6 Passat, does the front end really have to be put in the service position?

2) There were two options for the orifice tube: a "fixed" tube that is the standard OEM replacement for $2, and an "Automatic Adjusting Orifice Tube" for $20. Is there some benefit to the more expensive "automatic adjusting" tube? Any advice on this?

3) Since the compressor failure was not due to any internal components, I was not planning on having the system flushed. Does anyone think this is a big mistake ? If the system needs to be flushed, then I'd like to do it myself. If the flushing must be done, is there any advice on the best method to do this on the 2003 V6 Passat ?

4) As for evacuating the system and recharging: I'm considering doing this myself, just to make sure it's done correctly. I'm planning to buy the hoses and a vacuum pump from harbor freight. Any advice on this ?


Thank you again.

 

I strongly recommend that you do not attempt to re-gas the system yourself.
You could just replace clutch, then there is no need to open the system, the front would need to be put into service position for this.

 

I agree, but that's a lot of parts for just a dead coil clutch.
Can you not remove the clutch whilst the compressor is in place? I did this on my VR6 GTI.
Also, you can remove the compressor without having to put the front in the service position, it's a pita but possible.

 

Not sure on the answer to your questions, but I will advise you that if you have the compressor replaced (instead of just changing the clutch solenoid) you are typically required to also have the evaporator expansion valve replaced to honor the warranty on the replacement A/C compressor (that is if you decide to change the compressor). If the compressor fails within the ~90 day warranty period, the first thing they will ask for is documentation showing the expansion valve was replaced. If there is any trash or other obstruction restricting flow through this valve, the compressor won't last long!

I'd advise changing only the clutch solenoid (must remove clutch) only. Check with a reputable shop before proceeding.