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I got on the road today with my 5 y/o son and soon discovered that the A/C wasn't working. It was a little warm, but having A/C would have been nice. Now that were at our destination (1.5 hrs. to grandma/grandpa's house) and had a little time to research. I found this video:


I just did as the guy shows in the video, and it seems that it's the 384 relay. When I separate that connector by the power steering reservoir and supply 12v to the compressor side, the magnet energizes and the compressor spins. I'm going to test again and see if I get cold air. All I did was take a 14 ga. wire and touch the battery positive and the compressor-side connector.

All of the parts stores around here need to special order the relay; we're leaving for home tomorrow, so that won't work. I want to know if I can jumper the relay by doing exactly what I did to test it; when we are ready to leave, connect a wire between the battery and that connector and let it run for the ride home? I'm sure there are risks/issues I'm not considering.

Thanks!
 

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Me personally, I don't think that would be a good idea. The A/C compressor cycles when it runs, quite often actually. Having the compressor running continuously / non stop might freeze up something inside the car. Kinda like a de-humidifier does when it gets to dry. Ice forms all over the thing.

If you've got a few minutes to spare, I would pull out the relay and remove the plastic cover on it to expose the inside workings. Then take some fine emery cloth and slide that between the relay contacts.
Those contacts become pitted/burned after years of use from all that cycling on/off. Rubbing some of that carbon off the contact points just might get you going again.
Best way to do it, is fold over a small section of emery cloth so it's got the abrasive on both sides, slide it back & forth in between the contacts. Do that for a bit and plug it back in and test it.
 

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The risk would be that the compressor seizes, melts the wire and starts a fire since there is no fuse in it. If you added a fuse, you should be fine.
That said, when I 1st worked on the donor car, the previous owner did the exact same thing you suggested and his a/c worked fine. I don't know how long it was like that. I did repair his system to work properly as he had a bad connection at the pressure cut off and a gummed up a/c switch.
 

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Are you sure that there is enough refrigerant pressure to make the AC start? If you use an Ohm meter (DMM) to check resistance across the low-pressure switch, it should be nearly 0 Ohms. If not, then unscrew that switch, which will click if there is adequate pressure. If not, pressure is too low, or switch is bad. Don't worry about loosing refrigerant, because there is a schrader valve under it.
 

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Discussion Starter #5
Thanks for the replies! The good news is that it is cloudy and cooler today, so the need for A/C should be minimal.

I did as Andreas recommended - pulled the relay and opened it. I looked at the contacts closely and it looked fine, but hard to say if something else electronic in that unit failed. There is nothing obvious.

I forced the compressor to run for a bit yesterday and never got cold air to blow, so I'm wondering if I have any pressure in the system. I'm looking into a set of A/C manifold gauges to help me troubleshoot.
 

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If you can do AC work yourself, doing a full overhaul is not that expensive. Compressor, dryer, orifice tube & o-rings for about $300. Go overboard with a new condenser for another $60, and you’re good until 2034.
 

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Are you sure that there is enough refrigerant pressure to make the AC start? If you use an Ohm meter (DMM) to check resistance across the low-pressure switch, it should be nearly 0 Ohms. If not, then unscrew that switch, which will click if there is adequate pressure. If not, pressure is too low, or switch is bad. Don't worry about loosing refrigerant, because there is a schrader valve under it.
Good call.
I read into the post as the OP had a working system and then the relay failed. Seeing as no timeframe was given as to how long the system didn't work I didn't even consider the pressure switch.
 

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On a side note:
How come they don't put a site glass in the A/C system. I've had other cars with the site glass and it is an excellent feature.
It's unbelievably simple. Clear means you've got a fully pressurized system. Any bubbles means your losing pressure.
 

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On a side note:
How come they don't put a site glass in the A/C system. I've had other cars with the site glass and it is an excellent feature.
It's unbelievably simple. Clear means you've got a fully pressurized system. Any bubbles means your losing pressure.
It's been years since I have seen one. Last one I owned with one was a 92 Ford. Maybe the 134A does not work well with them?
 

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The 384 relay can fail, but it's typically cracked solder joints where the large tabs connect to the PC board. Typically, this manifests itself as intermittent A/C.

The 384 relay won't be commanded to energize if the low pressure switch is open (to protect the compressor). That sounds like the OP's problem.
 

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I got on the road today with my 5 y/o son and soon discovered that the A/C wasn't working. It was a little warm, but having A/C would have been nice. Now that were at our destination (1.5 hrs. to grandma/grandpa's house) and had a little time to research. I found this video:


I just did as the guy shows in the video, and it seems that it's the 384 relay. When I separate that connector by the power steering reservoir and supply 12v to the compressor side, the magnet energizes and the compressor spins. I'm going to test again and see if I get cold air. All I did was take a 14 ga. wire and touch the battery positive and the compressor-side connector.

All of the parts stores around here need to special order the relay; we're leaving for home tomorrow, so that won't work. I want to know if I can jumper the relay by doing exactly what I did to test it; when we are ready to leave, connect a wire between the battery and that connector and let it run for the ride home? I'm sure there are risks/issues I'm not considering.

Thanks!
Go to the nearest junkyard and yank that relay from any VW on hand - likely 2001 forward. Or you can take out the relay, pop open the case and re-solder the pin to the relay itself, the fault is 99% likely to be that one leg of the power pin or ground pins to the relay have a hairline crack and become intermittent. I just did both these things, pulled a junkyard relay, popped it in and have A/C again, then repaired the old one as a spare. Good luck with it.😊
 

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On a side note: How come they don't put a site glass in the A/C system. I've had other cars with the site glass and it is an excellent feature.
Your statement made me think of this on the bottom of the A/C compressor on our Passat.
97481

Is this not a sight glass? I know typically they are placed in the freon line. With this in the bottom of the compressor, is this one intended to ensure the oil level is correct?
 

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Your statement made me think of this on the bottom of the A/C compressor on our Passat.

Is this not a sight glass? I know typically they are placed in the freon line. With this in the bottom of the compressor, is this one intended to ensure the oil level is correct?
That sure is...
Where in the world is that located at? What year Passat do you have?
 

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That is the bottom of the A/C compressor. The left edge of the picture is the front of the car, the right edge is the rear of the car. August 2004 build date.
 

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Huh, I put a brand new compressor on my wife's V6 when I rebuilt that engine. I've had my hands on all the compressors I have on my other Passat's and I don't ever remember seeing anything like that.
Now I'm gonna have to check that out just to see.
 

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Thanks for the clarification woodardhsd. Are you by any chance in the Yuma vicinity?

Now that we know what it is, can someone explain to me what the purpose of being able to view it through the sight glass serves, ensure the system contains oil? I will guess the control valve's purpose is to regulate the pressure in the compressor?
 
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