MK6 Air Conditioning problems

[mtellez]

Hello every one, its been a minute since I've been here.
So on with the question, we have a 2012 Jetta TDI with over 200K and she runs like a scolded Gazelle.
My problem is A/C was not cooling well and its been some time since the last overhaul, so I pulled the pug and replaced everything normally done to make all things good under the hood.
New compressor, new Evaporator, Drier and Expansion valve, all new seals and Schrader valves. And luck for me my son runs a Ford dealership and his Master mechanic install everything.
We found that one of the fans wasn't working so we replaced that unit as well.
Still not cooling well. We live in Deep south Texas and boy is it hot it cools down to 65 deg's 4" in the vent with a outside temp of over 100 Deg.
The blending flaps looked to be in good shape and working well (so I'm told).
the solenoid on the back of the compressor came with the new compressor. So I am dumb founded as to what to do and how to attack it.
right now Mama is not happy and wants me to fix it, but no one down here know what going on.
Any help would be much appreciated.

 

[pkhoury]

You usually don't need to replace all that. If it's not cooling, the refrigerant control valve is notorious for failing. You drain all the refrigerant, unclip the snap ring, pull the RCV out, reverse install, pull a vacuum for like 30-60 minutes and refill.

I feel you on the heat. I'm in Hill Country and I'm glad my mk4's work as well as they do. The mk5/6 system, IMO, isn't that great.

I'm not an AC expert by any means, though I've replaced everything on a mk4 (for systems that didn't work because the compressor crapped the bed), but did the mechanic put in the right amount of R134a? I don't remember if the blend doors on a mk6 have the same problems as the mk4 and below.

 

[mtellez]

Thank you, and I agree about the RCV. It’s my understanding that was new and part of the new compressor unit. I will have to check and make sure that’s the case.

The tech that did the work is a master mechanic at the ford dealer, not to say he can’t make mistakes. I’m hoping he was smart enough to look up how much this particular unit takes.

I was told the high side was a bit high in pressure.

 

[oilhammer]

Wow... So, chances are the system didn't need ANY of that stuff. In any event, first stop should have been the car's own OBD. If you put a bunch of Chinacool stuff on, you may have introduced a new problem that wasn't even there before. It probably just needed a fan and an RCV.

 

[pkhoury]

Wow... So, chances are the system didn't need ANY of that stuff. In any event, first stop should have been the car's own OBD. If you put a bunch of Chinacool stuff on, you may have introduced a new problem that wasn't even there before. It probably just needed a fan and an RCV.

I was thinking the same thing. I only redid everything on two of my Golfs, because, well, it's 20+ years (and I know for a fact one compressor crapped the bed, because when Brian flushed the evap out, all kinds of metal fragments came out).

But on a newer car, yeah, I'd start with the fan and RCV first. I had a similar problem on my 2010 where I just needed a new fan to get AC working again.

@oilhammer can probably correct me on this, but I think high side pressure mostly reflects how much heat the compressor is transferring to the condenser. I'm probably wrong on this. I was talking to a good friend's AC tech and he was saying that it does depend on outside ambient temp, but 225-250 isn't uncommon.

 

[John Wesley Hardin]

Hello every one, its been a minute since I've been here.
So on with the question, we have a 2012 Jetta TDI with over 200K and she runs like a scolded Gazelle.
My problem is A/C was not cooling well and its been some time since the last overhaul, so I pulled the pug and replaced everything normally done to make all things good under the hood.
New compressor, new Evaporator, Drier and Expansion valve, all new seals and Schrader valves. And luck for me my son runs a Ford dealership and his Master mechanic install everything.
We found that one of the fans wasn't working so we replaced that unit as well.
Still not cooling well. We live in Deep south Texas and boy is it hot it cools down to 65 deg's 4" in the vent with a outside temp of over 100 Deg.
The blending flaps looked to be in good shape and working well (so I'm told).
the solenoid on the back of the compressor came with the new compressor. So I am dumb founded as to what to do and how to attack it.
right now Mama is not happy and wants me to fix it, but no one down here know what going on.
Any help would be much appreciated.

Hire an Illegal to fix it since most of the VW's are made in Mexico. Of course you gotta catch em before they get on the bus to New York! Using a Ford Mechanic to work on a VW is like hunting ducks with a .22 rifle hahha. No disrespect intended just a joke boys .

Dont live to far from you Homey. Just replaced my A/C compressor , condensor, and the thingy on the firewall. Had a friend from work charge the A/C proper with an emphasis on the high side pressure. Have ice cold air . Im sure my blend doors are no bueno. Went w/o A/C for months and arrived home incoherent . Now Im back to normal but still incoherent

 

[John Wesley Hardin]

Hire an Illegal to fix it since most of the VW's are made in Mexico. Of course you gotta catch em before they get on the bus to New York! Using a Ford Mechanic to work on a VW is like hunting ducks with a .22 rifle hahha. No disrespect intended just a joke boys .

Dont live to far from you Homey. Just replaced my A/C compressor , condensor, and the thingy on the firewall. Had a friend from work charge the A/C proper with an emphasis on the high side pressure. Have ice cold air . Im sure my blend doors are no bueno. Went w/o A/C for months and arrived home incoherent . Now Im back to normal but still incoherent
[/QU

I was thinking the same thing. I only redid everything on two of my Golfs, because, well, it's 20+ years (and I know for a fact one compressor crapped the bed, because when Brian flushed the evap out, all kinds of metal fragments came out).

But on a newer car, yeah, I'd start with the fan and RCV first. I had a similar problem on my 2010 where I just needed a new fan to get AC working again.

@oilhammer can probably correct me on this, but I think high side pressure mostly reflects how much heat the compressor is transferring to the condenser. I'm probably wrong on this. I was talking to a good friend's AC tech and he was saying that it does depend on outside ambient temp, but 225-250 isn't uncommon.
[/QUOTE I believe the high pressure side of A/C charging is critical to proper function of your A/C. My mechanic that charged my A/C , Jackson Specifically concentrated on the high side pressure when the temps were at about 100 degrees.

 

[mtellez]

Wow... So, chances are the system didn't need ANY of that stuff. In any event, first stop should have been the car's own OBD. If you put a bunch of Chinacool stuff on, you may have introduced a new problem that wasn't even there before. It probably just needed a fan and an RCV.

Well thanks for the response, but unfortunately both of those and more were replaced and still not working right. I got the parts at cost so that was not bad on the wallet and was intended to be sure there were no future problems for some time. Labor was free as well do to my sons position at the dealership.

 

[mtellez]

Well it’s down to trying to find the a way to check either by electrical testing or mechanically to determine what is the source of the issue.
I appreciate all the support, just need to find a way to check components before throwing any more money at it.

Like I said before, compressor is new as well as the PCV. Those to me would be the source of problem. Is there a reading I can take to confirm proper workings of individual items or is this a system thing?

The wife’s understanding but not happy, and I’m not happy to not have it working properly. VW’s have alway for me good, especially the Jettas, and I love the TDI especially when you dial them in. This thing Ali’s a beast on performance and beyond great on economy when you keep your foot out of it

 

[John Wesley Hardin]

Well thanks for the response, but unfortunately both of those and more were replaced and still not working right. I got the parts at cost so that was not bad on the wallet and was intended to be sure there were no future problems for some time. Labor was free as well do to my sons position at the dealership.

Replace fuse for the A/C clutch? maybe start with the simple things relays, fuses? Is the compressor kicking on ? Like I said my mechanic paid particular attention to the high side pressure when charging the A/C

 

[mtellez]

Replace fuse for the A/C clutch? maybe start with the simple things relays, fuses? Is the compressor kicking on ? Like I said my mechanic paid particular attention to the high side pressure when charging the A/C

Thank you and yes the clutch is new and compressor is working, I’m guessing I will need to pull my gauges out and verify pressures, not being a W tech or an A/C tech not sure what I’m looking for, meaning pressures.

 

[John Wesley Hardin]

Replace fuse for the A/C clutch? maybe start with the simple things relays, fuses? Is the compressor kicking on ? Like I said my mechanic paid particular attention to the high side pressure when charging the A/C

Thank you and yes the clutch is new and compressor is working, I’m guessing I will need to pull my gauges out and verify pressures, not being a W tech or an A/C tech not sure what I’m looking for, meaning pressures.

Well Im not sure what they are supposed to read. Thats why I had a friend of mine who is a mechanic where I work recharge the system. It took him about 40 -45 minutes to charge the system. He also had a chart on his cell phone that showed what the high pressure should read at outside temperatures . The higher the outside temp. the higher the pressure needed on the high side of the gauge. He also had a handheld sensor to check for refrigerant leaks that made an audible warning if there was a leak . He found one and tightened the fitting. You sure you dont have a leak? Maybe the refrigerant leaked out . I was impressed the way Jackson charged the system and surprised it took that long. I replaced everything you did probably less I got ice cold air. He took his time and did a thorough job . His emphasis was on the high pressure side with high outside temp.

 

[John Wesley Hardin]

Well Im not sure what they are supposed to read. Thats why I had a friend of mine who is a mechanic where I work recharge the system. It took him about 40 -45 minutes to charge the system. He also had a chart on his cell phone that showed what the high pressure should read at outside temperatures . The higher the outside temp. the higher the pressure needed on the high side of the gauge. He also had a handheld sensor to check for refrigerant leaks that made an audible warning if there was a leak . He found one and tightened the fitting. You sure you dont have a leak? Maybe the refrigerant leaked out . I was impressed the way Jackson charged the system and surprised it took that long. I replaced everything you did probably less I got ice cold air. He took his time and did a thorough job . His emphasis was on the high pressure side with high outside temp.

Thank you and yes the clutch is new and compressor is working, I’m guessing I will need to pull my gauges out and verify pressures, not being a W tech or an A/C tech not sure what I’m looking for, meaning pressures.

Did you replace the condenser?

 

[mtellez]

Did you replace the condenser?

No sir. Condenser was not changed. Evaporator , expansion valve, drier, oil, Schrader valves, O Rings, clutch and compressor, Pressure control valve all changed.

 

[oilhammer]

You need to first start with communicating with the Climate module, and see what the refrigerant pressure sensor value is, and if there are any DTCs stored.

 

[mtellez]

I’m guessing that is done through the OBD port or directly to the module?
Does that require special software?
What am I looking for?
My chart only goes to 95deg F
Ambient. Low. High

90	49-58	243-261
95	53-58	266-289

 

[oilhammer]

Yes, like all modern cars, it uses the DLC and any appropriate software that speaks Volkswagen can talk to all the modules, including the Climate.

 

[John Wesley Hardin]

No sir. Condenser was not changed. Evaporator , expansion valve, drier, oil, Schrader valves, O Rings, clutch and compressor, Pressure control valve all changed.

Not sure on a 2015, but on my 2003 Jetta they recommended changing the condenser, when you change the compressor. along with other parts. I got the the whole compressor kit including condenser on Rockauto . So far everything has worked out well

 

[pkhoury]

Not sure on a 2015, but on my 2003 Jetta they recommended changing the condenser, when you change the compressor. along with other parts. I got the the whole compressor kit including condenser on Rockauto . So far everything has worked out well

Yup. Condensers are pretty cheap, though. As for me, when I've replaced the whole system on my Golfs, I kept the evaporator and used AC flush on it, because I didn't feel like spending an extra 3-4 hours to pull the dashboard apart.

I'd try and see if the compressor is at least engaging when the AC is supposed to be running, and like @oilhammer says, check the air conditioning module in VCDS to see if there are any codes/etc.

As for pressures, I'm not sure if the JSW is the same as the mk4, but at idle, I'm aiming for around 30psi on the low side, and high should be between 200 and 250, probably closer to 250. One of my Golfs was a little over-filled. Let some refrigerant out, and now the car gets down to about 39 degrees while I'm running (with ambient Texas temps of about 95).

 

[John Wesley Hardin]

Dont know about other vehicles. The condenser on my 2003 Jetta is located behind the radiator. had to take the shroud off and so on. A pain in the butt. However I didnt want to do the A/C twice. After or before a certain year the passages are to small to flush condenser effectively, so its better to replace.

 

[oilhammer]

The OP is asking about a 2012 NCS Jetta. Shares no HVAC parts with your 2003, and works slightly differently. Your comments do not help here.

 

[pkhoury]

The OP is asking about a 2012 NCS Jetta. Shares no HVAC parts with your 2003, and works slightly differently. Your comments do not help here.

Plus you have the CAN-bus component, which the mk4 vehicles don't share, either, and the compressor design is totally different.

 

[oilhammer]

The 2000+ A4 cars have CAN, but it isn't used for HVAC unless you have Climatronic which none of our US-Canadian spec TDIs had from the factory.

 

[FJ40Jim]

I'm gonna jump in, rather than starting another mk6 AC thread.
Subject car: 2012 JSW TDI, low options, manual AC.
Symptom: no AC cooling.
Tests: checked pressures, thinking it was low on R134 since it's never been serviced AFAIK. Step 1, Gauges showed normal rest pressures on H & L sides, 150-180psi. Hmm, that's adequate.
Step 2, Started engine, engage AC, pressures remain exactly the same. Verified pulley is spinning and compressor shaft is turning. No bad noises from compressor, probably just needs an RCV.
Step 3, Installed new FCM & main fan because it had been acting up occasionally. Install new RCV, vacuum, hold for leak test, begin charging. Engine running, AC on max, both sides are showing 40-45psi, no difference between H&L. Well crap, it should be showing almost zero on L and 50 on H.
Step 4, Fire up slow-azz antique laptop & run VCDS. Values show 0.0A to RCV, compressor commanded off, system pressure is zero. (Yes, I know this shoulda been step 1, but reasons)

Now what? System pressure is definitely 2.x atmospheres, well above zero. I don't think charging more is gonna fix it because 9atm of pressure was not working previously.

Is there a way to test the AC pressure sensor directly, or bypass it to temporarily force RCV engagement? My understanding is it is a sensor, not an old fashioned binary or trinary switch, so not a "check for continuity with test light" kinda deal.

Thanks for any insight.

 

[oilhammer]

If the refrigerant pressure sensor value is '0', then there will be no command sent to the RCV to make the compressor work. And you are correct that it is a sensor, not a simple switch. They do fail sometimes, although the Climate module *usually* will store a DTC but not always. I've also found them to sometimes have wire damage near the connectors on some models where they are easily exposed and possibly bumped by some other non-related service (like a headlamp bulb replacement).

 

[FJ40Jim]

Followup to the 0.0 pressure reading:
Unplugged sensor to check electrical connection. Tight & clean, no problem there. Check again w/VCDS, shows error at pressure sensor. Plug sensor back in, reads 0.0 pressure. Conclusion: wiring is OK, transducer is bad. Ordered new sensor.

Tried unthreading sensor, but it just twists the soft aluminum AC tube it's threaded onto. I don't see any way to counterhold the tube, only wrench flats on the sensor. Should I get a new AC hose also?

 

[oilhammer]

This is where the loss of my ETKA machine frustrates me so... because I could better tell you what you need. BUT... I am *pretty sure* the line that has the sensor in it, comes WITH a new sensor. So if you order the line, you get it all (and the o-rings on both ends). That may be your best bet, but check the dealer for sure.

 

[FJ40Jim]

Thanks OilHammer!
The correct compressor discharge hose is 1K0 820 721 CA. Pics show it comes with the pressure sensor installed and o-rings on each end. Also available aftermarket as Vemo V10-20-0003, though it's out of stock everywhere.

I'll order & install the hose assembly, and post up results.

 

[oilhammer]

Cool (no pun intended), keep us posted!

 

[NevilleMccoy]

If you put a bunch of Chinacool stuff on, you may have Speed Test introduced a new problem that wasn't even there before. It probably just needed a fan and an RCV.