2010 Passat AC on the Fritz

[nmwhitney]

2010 VW Passat Wagon. 2.0 TSI CCTA. 6spd DSG.

Never fails that hot weather brings AC problems. AC stopped cooling last week. Research indicated that the compressor control solenoid valve was a likely culprit... for $45 bux plus 2 cans of r134a it seemed a reasonable gamble. Had the freon evac'ed (it was full... no leaks). Replaced the valve (almost conveniently located on the underside of the compressor). Vacuumed the system down for 60+ min. Verified it held 29+ for another half hour.

Then I started to fill (vapor fill on low side... I've since learned that's not the best way to start, but I digress). So it's a 600g system. And only got about 120g in before it stopped taking freon. Low side was reading high (between 80-90). I stopped filling and closed off the valves on the manifold and let the system settle. After 20 min, Low side was reading 85, the high side was reading between 80 and 85. Close enough to equal to determine compressor wasn't creating any pressure.

NOTE: Compressor clutch was engaged, manifold side of gauges were closed, port side of gauges were open. Hot air at the vents. Low side and high side tubing were both cool-ish to the touch.

ALSO NOTE: Before the evac, I hooked up the manifold gauges and noted an abnormally high reading on the low side... 200+. I don't recall what the high side was, but it looked to be at a normal range... probably around 200. This was with the car off, not warmed up.

ALSO ALSO NOTE: Full disclosure: The serp belt was chirping a bit when the ac was engaged and taking off from a dead stop. I replaced the belt and tensioner and the chrip stopped, but it did come back in the days leading up to the ac failure.

My guess at this point is that the compressor is knackered. It's never made any loud, rattling noises so I'm hopeful it didn't implode.

But how far do I go on the repair? Just replace the compressor? Should I replace the TXV and/or condenser as well? I know the "proper" answer to that, so let me explain... The Compressor and TXV are easily replaced on this car. The drier is integrated into the condenser. Excavating the condenser/drier however, requires darn near a complete tear down of the front of the car... bumper cover, bumper frame, headlights, radiator support... you get the idea. That's a couple days work for me. But I sure as heck can't afford to pay anyone to do it.

Can I get away with just a compressor (assuming that's the problem)?

[bohica2xo]

The primary filter on MVAC systems tends to be the Condenser. So it all depends on how much metal the compressor shed before quitting.

That PXE compressor is not as bad as a scroll type for trash production while running. Did you see any debris on the control valve when you removed it?

A compressor only job is a bit of a gamble, but I feel your pain on the condenser replacement. A $300 coin toss.

Do you have the time and the space to excavate the condenser? Is the rest of the car in decent shape? Do you have transportation if the car is down?

On this board I am a strong believer in "Fix it Right, Fix it ONCE". I understand your circumstances may dictate the gamble, but a condenser is 30% of the price of a compressor...

[nmwhitney]

No debris in the control valve when I changed it. Some oil dribbled out and what I saw appeared clean and clear… no grit.

I’m like you, do it once and do it right… and I know replacing the drier is key. But damnation, what a pain to get to it. And if I’m going that far in, where do I stop… condenser, radiator, intercooler?

I have a place to work and the tools… it’s merely a time issue. A full weekend to do the tear down and reassembly vs. 2.5 hours to swap the compressor, vac it down, observe and recharge.

[bohica2xo]

Yeah, if I had a 14 year old radiator out of the car I probably would not put it back in...

How many miles on the car? Had it since new, keeping it forever?

I feel your pain. But the decision is yours. If you do a compressor R&R, add some oil and go, it may well go another 50,000 miles. And the O ring seal on the plastic radiator tank could let go next month.

[nmwhitney]

Bought the car 2 months ago for the female 16 yo offspring unit to drive. 120k on the clock. Cosmetically and mechanically the car is an 8/10. I'd like to get 60-80k out of it.

I've owned enough German cars at this point to know that as they age, they don't like to be effed with. By that I mean you start doing a major diy repair and something else expensive (or unobtainium) will inevitably break while you're in there. Plastic coolant lines/housings on VW's being the chief offender... but they won't go ahead and break right then... they wait a few hundred miles.

FCP Euro has a compatible Nissens compressor for $200 with a promo code right now. VERY tempting...

[bohica2xo]

16 year olds seem to have the unerring skill to stuff the front end within the first few months.

In your case I would go for the $200 compressor and wait for the need to pull the front end apart.

And yes plastics all get brittle with age. Anything here in Las Vegas that has been outside for 10+ years is going to be iffy on the plastic parts..