A/C Variability Issues

[elamothe15]

Just wondering if anyone else has noticed any of these issues (not Cimatronic)...

I noticed a couple months ago that when the fan was off (windows down) that fairly warm air was blowing through the vents into the cabin. I thought it might've been something that I just didn't notice in the past, but then I noticed that it happens very intermittently. I know that air still flows by with the fan off, but typically it would just be air similar to outside air temps, not hot air.

Then just last weekend with the A/C on halfway between max A/C and neutral that the air wasn't cold at all and rather neutral. I turned the dial to max A/C and it began to get very cold (like it should). I put it back to the original position of halfway between max and neutral and it was disgustingly cooler than before.

Not exactly sure how these systems operate, but has anyone else experienced either of these issues? Have you brought it to the dealer to have it looked at?

My guess is the "temp" dial is a potentiometer which controls a mixing flap to regulate air temp. I'm wondering if the mixing flap (if this is how it operates) is sometimes getting lost and is causing both issues when setting "temp" and turning the fan off.

 

[tmcbride]

I don't know much about how this works and I have only had the car a few months, but something I noticed that I think is similar to your description is that even when the car has been on for a while if I am just puttering around town with the A/C set to a certain point, if I go on the highway or just get the revs up for whatever reason it gets noticeably colder without moving the temp knob. So I don't think it can be relied on that the knob is set at this point and it will be exactly this cold like you would expect with something like climate control where you set the actual temperature. I find myself fiddling with the temperature a lot more than in past cars that had climate control.

I expect that this is normal behavior as long as the A/C does actually get cold. I doubt a dealer will do anything unless it is actually not functioning at all.

 

[heydabop]

Regarding the first issue, were you moving and was recirculation off? As I understand it (as was my experience in other vehicles) if you have the A/C off and also have recirculation off, your vent is essentially a duct to the outside world, and air will be forced in from the forward movement of your car. If you turn A/C off and recirculation on, then you'll have a closed loop with no air being pushed through it.

 

[GLoBaLReBeL]

Heyadabopis right. If re-circulation is off, air is allowed in through the vents outside whether A/C is on or not.

When extreme stress is put on the car with A/C on (during WOT situation) the A/C will actually shut off to give you more power. You will hardly notice this from the air coming out, but it is worth it as our A/C strips a ton of power from our cars.

you will also notice that after turning off A/C (after being on for a while) and having re-circulation off, that you will get cool air for about 2 minutes after. This is just the coils stills giving off a cooling effect.

 

[elamothe15]

I don't know much about how this works and I have only had the car a few months, but something I noticed that I think is similar to your description is that even when the car has been on for a while if I am just puttering around town with the A/C set to a certain point, if I go on the highway or just get the revs up for whatever reason it gets noticeably colder without moving the temp knob. So I don't think it can be relied on that the knob is set at this point and it will be exactly this cold like you would expect with something like climate control where you set the actual temperature. I find myself fiddling with the temperature a lot more than in past cars that had climate control.

I expect that this is normal behavior as long as the A/C does actually get cold. I doubt a dealer will do anything unless it is actually not functioning at all.

I agree that it'll be a tough thing to bring up to the dealer since it is still getting cold. But it just seems odd that it was not always an issue and the temps are very variable at times when playing with the knob.

Regarding the first issue, were you moving and was recirculation off? As I understand it (as was my experience in other vehicles) if you have the A/C off and also have recirculation off, your vent is essentially a duct to the outside world, and air will be forced in from the forward movement of your car. If you turn A/C off and recirculation on, then you'll have a closed loop with no air being pushed through it.

This is when moving and re circulation is off. I agree that the air forced in from the forward movement is from the outside world, but the air temp is actual significantly warmer than the outside air temps. As I mentioned my windows are open and I feel the warm air from the ducts

 

[Juggar]

our A/C strips a ton of power from our cars.

Was the same way in my 2015 Jetta 1.8t, and feels the same in the GTI.

Saleswoman kept trying to turn it back on, she looked like she was going to die so we kep it on during the test drive but seriously, come on.... I can't fully test the car with the A/C compressor on. Of course its news to her that the A/C sucks power, she drives a loaded CC and could care less. Im buying a GTI for the performance factor first and foremost, you could delete the A/C I do not care and do not need it.

 

[The Fed]

Or it could be the swash plate control valve.

 

[MSchott]

Heyadabopis right. If re-circulation is off, air is allowed in through the vents outside whether A/C is on or not.

When extreme stress is put on the car with A/C on (during WOT situation) the A/C will actually shut off to give you more power. You will hardly notice this from the air coming out, but it is worth it as our A/C strips a ton of power from our cars.

you will also notice that after turning off A/C (after being on for a while) and having re-circulation off, that you will get cool air for about 2 minutes after. This is just the coils stills giving off a cooling effect.

This is close to how I understand the system works. If the AC is on in some conditions it shuts off but not just high stress. It happens under steady state driving conditions too. There's a clutch that controls this. It's for the sake of efficiency. My guess is its thermostatically controlled

 

[georgeh01]

I took my '15 2.0 GT back to the dealer as I was having the same issue (among many many others). They did their tests and looked for faults and found that there was a vent/valve sticking open.

They booked my Car in for the following week to fix it, but stated that it would obviously require removing the entirety of the dashboard. On day 3 of leaving my Car with them, they phoned to say they couldn't find any problem and they sent a video of one of their technicians simply pointing a thermometer at one of the dashboard outlet.

It was a waste of time, and it seems that the sticking valve is intermittent. I'm sure I can keep taking it back but sometimes the fault might show up, and others it might not, so I figure I'd just be wasting my time even further.