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Air Conditioning Half Works

rfc89747

Ready to race!
Location
Pennsylvania
Today driving home from work in 90F ambient temps, I noticed my interior was not cooling normally. I have the dual climate control and set both sides to sync at 68F. The blower speed never decreased on my 40 minute commute. I could feel normal cool air coming out of the driver side vents, but the passenger side was barely cool/slightly warm air.

Has anyone had this issue before? I tried pulling over and restarting the car, but that didn't seem to change anything. I also tried max ac, de-syncing and setting the passenger side to cooler than the driver, and changing to foot well only. No change.

Edit: Update on this. I just tried the vent re calibration (hold middle vent button and AC button). It did it's thing, but didn't correct the issue. I scanned for fault codes using obdeleven nothing found. I used the output test options and ran a few of the flap tests which all seemed to be working normally. Following those tests the air seemed to be coming out equal on both halves of the cabin. It may have just been because I was parked in the shade and things were cooling down, but I did kick it into max AC and it seemed to cool evenly. I parked it in the sun, and will check it again in about 30 minutes. I also noticed a hissing sounds coming from the vents when I shut the car off.
 
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rfc89747

Ready to race!
Location
Pennsylvania
Update on this. It still doesn't work. It isn't too noticeable in normal temps, but when the car has been sitting in the heat, it just can't recover with half the car not blowing cool. I suppose I will book an appointment at the dealer. Good thing I'm just 2,000 miles over the bumper to bumper...
 

Wrath And Tears

Go Kart Champion
Location
Azusa, CA
The refrigerant levels might be low due to a leak. They lose about 10% charge a year, so you shouldn't be having issues unless there is a leak, or if a flapper motor or flap is broken. That could also cause the issue. I think a faulty heater valve can have the same effect.
 

Amm5890

Passed Driver's Ed
Location
USA ??
Try changing ac output to "hot country" via obdeleven. It's been awesome at bringing my cabin temps down faster during this hot summer
 

Wrath And Tears

Go Kart Champion
Location
Azusa, CA
Try changing ac output to "hot country" via obdeleven. It's been awesome at bringing my cabin temps down faster during this hot summer
That has worked for a lot of people for sure, but would not help the fact that the passenger side isn't blowing cold. That is a sign of a few things, but normally that only half of the evaporator is getting cold, normally a sign of a low charge. Like I said in my first post it can also be a motor or flap issue, and I will add that a scan of the car would help reveal the issue, as well as you can log the vent and evap temps to see what is going on.
 

KevinC

Autocross Newbie
Warm on one side and cool on the other is an indication that you're low on refrigerant, which means you have a leak someplace. Get it fixed under warranty if you're still under 36k miles, or find a qualified AC shop if you're not. Good luck!
 

rfc89747

Ready to race!
Location
Pennsylvania
Okay so I gathered some more information. Sent my borescope into the middle vents and took a look at any moving parts I could see. Here are the two temperature control flaps for the driver and passenger sides. To my eyes they both seem to be operating normally. These videos were taken while the OBDEleven app was running a actuate driver and passenger side temperature control flaps test.

Driver: https://youtu.be/sZ0bHmn4uH8
Passenger: https://youtu.be/274SnwPb7Go

Additionally I grabbed some temps along with compressor load and pressure from OBDEleven. Outside temps were about 85F (29C) with no sun, so it actually did cool the cabin quiet easily during these tests and get to a point where the blower was on low, but the passenger side was always slightly warmer.

This is after running the AC for a few minutes at a synced temp of 70F (about 21C)


This is after running Max AC for a couple minutes (temps seemed to go up?)


This is after leaving the system completely off (blower and AC) for about 2 minutes.


And finally, this is after running the AC for about 15 minutes at a snyced 68F (20C).


I'm honestly not sure what to make of all this. The actuators do seem to be working normally, but the temps show that the driver side (left) is consistently cooler than the passenger (right). Is there a separate zone in the compressor for each side or something like that? Why would the temps get hotter when using max AC? In any case, hopefully the data can at least help someone looking in the future and possibly when I take it to the dealer to save them diagnostic time.
 

kevinkar

Ready to race!
Location
United States
I've noticed max fan speed means more air but less cool as well. Speed 3/4 (SE here) is coolest temp.
I've found this true of every car I've ever owned. Max is usually good for the first few minutes to circulate as much air as possible and get it all down to some more manageable temp but, after a while, you're now pushing it around too fast and the air is not able to dump heat enough. But if you drop the fan speed down a notch or two, it now dumps the remaining heat better and the air coming out of the vents is (or at least feels) cooler.

Also cracking the windows a bit to get the hotter air at the roofline to dump out of the car as the cooler air fills up the cabin from the bottom since warmer air rises then close them fully as necessary.
 

Mk7Will

Ready to race!
Location
Temecula
???

The a/c system is completely sealed, and loses nothing at all unless something's broken.
That is incorrect, every ac system will lose some charge during the year. Back in the day topping off R12 at every service was the norm. The recent system like r134 and the newest system r1234 will still lose charge. The seals are never perfect. Keep in mind the receiver drier will store refrigerant so it will take generally a few years before it becomes in issue. Like someone previously mentioned, it could be low of refrigerant due to the temp difference in the evaporator. Best bet would be to take it to your local VW dealer.
 

Mk7Will

Ready to race!
Location
Temecula
Everything you are showing is a clear sign of low refrigerant. When refrigerant is passed through the expansion valve is begins to cool the evaporator. When you have a low charge there is insufficient refrigerant to cool the evaporator evenly and it flows driver side to passenger side causing higher temperatures to come from the passenger side


Okay so I gathered some more information. Sent my borescope into the middle vents and took a look at any moving parts I could see. Here are the two temperature control flaps for the driver and passenger sides. To my eyes they both seem to be operating normally. These videos were taken while the OBDEleven app was running a actuate driver and passenger side temperature control flaps test.

Driver: https://youtu.be/sZ0bHmn4uH8
Passenger: https://youtu.be/274SnwPb7Go

Additionally I grabbed some temps along with compressor load and pressure from OBDEleven. Outside temps were about 85F (29C) with no sun, so it actually did cool the cabin quiet easily during these tests and get to a point where the blower was on low, but the passenger side was always slightly warmer.

This is after running the AC for a few minutes at a synced temp of 70F (about 21C)


This is after running Max AC for a couple minutes (temps seemed to go up?)


This is after leaving the system completely off (blower and AC) for about 2 minutes.


And finally, this is after running the AC for about 15 minutes at a snyced 68F (20C).


I'm honestly not sure what to make of all this. The actuators do seem to be working normally, but the temps show that the driver side (left) is consistently cooler than the passenger (right). Is there a separate zone in the compressor for each side or something like that? Why would the temps get hotter when using max AC? In any case, hopefully the data can at least help someone looking in the future and possibly when I take it to the dealer to save them diagnostic time.
 

Stickman

Passed Driver's Ed
Just to clarify the comment about using the "Hot Country" setting. VW did a massive overhaul of the coding in numerous categories on cars built sometime after mid December 2016. As a result there is no Hot Country setting so the only way to adjust the cold air output is by changing the Run Time and then re-initializing the system. FWIW
 

emanon

Ready to race!
Location
SoCal
Just to clarify the comment about using the "Hot Country" setting. VW did a massive overhaul of the coding in numerous categories on cars built sometime after mid December 2016. As a result there is no Hot Country setting so the only way to adjust the cold air output is by changing the Run Time and then re-initializing the system. FWIW
That's not true at all, you just have to go into the long coding. I just did it on my 2017.

Sent from my SM-G965U using Tapatalk
 

emanon

Ready to race!
Location
SoCal
What was your build date?
4/17. Mine has all the 2017 coding quirks. Hot country is there, in the AC menu, iirc it's under byte12 in long coding, select 10 at the top, and check hot country. I can screen shot it in a bit if needed.

Sent from my SM-G965U using Tapatalk
 
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