2007 Jetta 2.5 AC Compressor Question

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
231k on car. AC system unopened until I replaced the RCV because it would not turn on. Turned on fine after that, but a lack of cooling and low side pressure is too high and high side pressure way too low. Probably compressor failure. Since the system holds pressure and has not been opened up except for quick RCV change, can I get away with just replacing the compressor or would you guys do the whole thing: expansion valve, receiver dryer, condenser and compressor? THANKS!
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Turns out I screwed the pooch and overcharged it. Pulled a vacuum for an hour, put in approx 493g of R134 or so, the lower limit of 525g +/- 25g. Used a kitchen scale to measure the fraction of the second can. She's blowing high 30s F on an 81 ambient day and I hope she keeps on blowing like that.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Thanks oilhammer, I'm going to let it settle down a bit and record the pressures in a day or so. Will also scan and record the measuring blocks. Thanks again.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Update. Blew 38 at the vents for two days of 80 F weather. Went outside to take pressures today and it did not turn on for a few minutes. When it did, it blew 38 F at the vent with an ambient temp of 62F. Pressures were 30 / 135 which is fine. Now the mystery is why the delayed engagement. As soon as worn out laptop charges up I'll check scan for DTCs again. Any most likely cause of delayed engagement?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
You likely have a bad refrigerant pressure sensor. There is a TSB about it, and an updated part number.

5K0-959-126
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Thanks, does it vent refrigerant when you change it? I know very little about AC. I scanned the car and no codes. Is the sensor the little guy sticking straight up near the AC compressor pulley?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Yes, you'll lose the charge. And yes, it is the one near the compressor that connects straight up, sort of below the headlamp area.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Keep in mind, sometimes the refrigerant will leak THOUGH that sensor, and be trapped between the sensor body and the connector shell, and since the connector shell as a weather proof seal on it, as well as each of the wires having their own little seal through the connector body, that tiny bit of R134a will camp out in there and be under pressure. Tiny volume, BUT it can be enough to make it so the connector is hard to remove, because it is forcing it up against the little lock tab.

Normally, as you probably already know, the easy way to disconnect those style of connectors is by gently pushing them ON a little bit and THEN pulling on the release so that the little tab isn't in a bind.
 
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