Air conditioning blowing hot air in '14 Q5. What things should I be checking?
09-22-2019, 06:25 AM
#1
AudiWorld Expert
Thread Starter
Air conditioning blowing hot air in '14 Q5. What things should I be checking?
No fault codes. Still blows hot even when put down to "LO" temp, so I'm assuming it's not a temp sensor issue, but rather the AC itself. I think one time I heard fluid flowing - is that indicative of something? I've never done AC recharge nor know what's exactly involved, if that's the issue...
Last edited by Mark P; 09-22-2019 at 07:59 AM.
09-22-2019, 12:16 PM
#2
AudiWorld Senior Member
First place I'd look is the high pressure cutout sensor.Cheap and a common point of failure.What did you use to scan for codes VCDS?
I would expect that to pickup a faulty sensor.Any other type of scanner/software - who knows.
I would expect that to pickup a faulty sensor.Any other type of scanner/software - who knows.
09-22-2019, 01:35 PM
#4
No fault codes. Still blows hot even when put down to "LO" temp, so I'm assuming it's not a temp sensor issue, but rather the AC itself. I think one time I heard fluid flowing - is that indicative of something? I've never done AC recharge nor know what's exactly involved, if that's the issue...
09-23-2019, 12:46 PM
#5
AudiWorld Expert
Thread Starter
That's a good place to start looking. If that goes out the compressor won't run. There was a TSB for that switch for MYs 2013 & 2014 (see attached). It is easy to access and there's a schrader valve under it so they don't have to pull the charge to replace it. There's a list of faulty sensor production dates in the TSB. The number is stamped on the sensor so you can, after removing the plastic cover over the radiator and with the aid of a mirror & flashlight, check yours. You might get lucky and find that's all it needs!
It seems like I would want to check:
- Interior Temp Sensor
- Exterior Temp Sensor
- AC Pressure Sensor (G395)
If the pressure is reported as normal (what is normal?)
-> then it would seem that the pressure sensor may be working correctly and the issue is elsewhere.
If it reports low, then either the sensor could be faulty or really the pressure is low.
-> If the sensor is in the known-faulty date range, replace it.
-> If the sensor is outside the known-faulty date range, replace it anyway because it's only a $50 part?
If replacing sensor doesn't fix it
-> Then assume truly low pressure and get recharged?
I also bring up the temperature sensors as I recall I had a similar issue in my B5S4 and turned out to be the one in the air duct behind glovebox. I was able to check sensor values through hidden HVAC menu noted here:
https://www.audiworld.com/tech/int6.shtml
I had captured some of those details in another thread posted here:
"You'll want to do this:
1.) Press and hold the recirculation button.
2.) Then press the manual flow control up arrow. You should see a 1c.
3.) Press the temperature up ("+") or down ("-") buttons to select a code number.
4.) Then press the recirculation button again. The value should display.
5.) Press the temperature up or down button again to display another code.
and choose 58, then 59:
58 Temperature in deg C, from Fresh Air Intake Duct Temperature Sensor (G 89)
59 Temperature in deg C, from Outside Air (Ambient) Temperature Sensor (G 17), front
Do it when the instrument cluster is reading incorrectly and you should see that one of these values is completely wrong.
So is there anyway to find such values through HVAC or VCDS of the sensor readings? Where/How?
09-23-2019, 03:03 PM
#6
AudiWorld Member
The A/C failed in my 2014 Q5. It was awful. Audi ran tests and recharged the system. A few months later it happened again. On their next try they found the schrader valves were faulty and replaced them. Been fine ever since.
My blower motor got replaced as well when it started screeching. That noise just came back. Why again did I buy an Audi? It amazes me how many parts fail prematurely on Audi/VW products.
Check for leaks if it is blowing hot.
My blower motor got replaced as well when it started screeching. That noise just came back. Why again did I buy an Audi? It amazes me how many parts fail prematurely on Audi/VW products.
Check for leaks if it is blowing hot.
09-23-2019, 04:31 PM
#7
AudiWorld Expert
Thread Starter
That's a good place to start looking. If that goes out the compressor won't run. There was a TSB for that switch for MYs 2013 & 2014 (see attached). It is easy to access and there's a schrader valve under it so they don't have to pull the charge to replace it. There's a list of faulty sensor production dates in the TSB. The number is stamped on the sensor so you can, after removing the plastic cover over the radiator and with the aid of a mirror & flashlight, check yours. You might get lucky and find that's all it needs!
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09-24-2019, 09:16 AM
#8
Mark,
Yes it could be. It could also be 50 or so other things. These systems are extremely complex / over-engineered. Kinda like flushing a toilet with a pinball machine as the saying goes. I have a 270 page Audi Q5 HVAC repair manual .PDF from 2008 if you need some light reading. It’s too big to attach here so PM me if you’d like and I can email it to you. Most of the diagnostics and testing procedures section refer to the VAS 5051 tool and guided fault finding, as in “Take it to the Dealer”. There are some interesting sections and pictures about the system operation though that show how complicated it really is. Some things have probably been changed since it was written but some are probably still relevant.
09-24-2019, 09:32 AM
#9
AudiWorld Expert
Thread Starter
Mark,
Yes it could be. It could also be 50 or so other things. These systems are extremely complex / over-engineered. Kinda like flushing a toilet with a pinball machine as the saying goes. I have a 270 page Audi Q5 HVAC repair manual .PDF from 2008 if you need some light reading. It’s too big to attach here so PM me if you’d like and I can email it to you. Most of the diagnostics and testing procedures section refer to the VAS 5051 tool and guided fault finding, as in “Take it to the Dealer”. There are some interesting sections and pictures about the system operation though that show how complicated it really is. Some things have probably been changed since it was written but some are probably still relevant.
Yes it could be. It could also be 50 or so other things. These systems are extremely complex / over-engineered. Kinda like flushing a toilet with a pinball machine as the saying goes. I have a 270 page Audi Q5 HVAC repair manual .PDF from 2008 if you need some light reading. It’s too big to attach here so PM me if you’d like and I can email it to you. Most of the diagnostics and testing procedures section refer to the VAS 5051 tool and guided fault finding, as in “Take it to the Dealer”. There are some interesting sections and pictures about the system operation though that show how complicated it really is. Some things have probably been changed since it was written but some are probably still relevant.
09-24-2019, 11:59 AM
#10
AudiWorld Super User
FWIW, seems like sort of too much analysis on front end for most common issues. Since you have VCDS look for basic sensor codes. If none--which sounds like the case--head to any A/C shop and have them recharge it. Probably 90-95% that resolves it for the next 5 years. Any shop with the vacuum and recharge set up can do Audi's. There is no magic Audi Pixie dust to it and a more rational repair bill follows.
Filled by weight, so they don't just top it up. Step one for them is to evacuate system. The store shelf DIY can ideas can lead to blown compressors and nightmares if overcharged. As part of the service, you can get the weights pre and post too, so you know if it was short on refrigerant.
For a casual fly by, even with the newer refrigerants like R134, there are ozone issues. That puts a lot of pressure on the auto companies to reduce use of it, maybe more so in Germany. Systems have shrunk way down in terms of total capacity. To cool same vehicle, these use like ⅓ of what they did into the 80's with R12. Thus loss of relatively minor amounts in absolute terms is a big percentage loss. From BTDT on my 2006 A8--any many other similar postings on the D3 board--once you lose about half the refrigerant by weight, it's all over. Total capacity on that one is 630g IIRC, and when it came up with 300g + as what was evacuated, it told me that missing 330 g or so was enough to take it out. That is one can or less of a lot of the store shelf can compressor grenades. First, system is sort of erratic and maybe feels humid, then it just drops off to nothing as far as my typical symptom experience. My sense from D3 is to expect charge life on these kinds of systems may be on order of 6 or 7 years, with no obvious leaks. If you have it charged and it flakes again after first working well, obviously have it leak checked with a uV dye. Or, have some put in preemptively as part of fill if desired.
Filled by weight, so they don't just top it up. Step one for them is to evacuate system. The store shelf DIY can ideas can lead to blown compressors and nightmares if overcharged. As part of the service, you can get the weights pre and post too, so you know if it was short on refrigerant.
For a casual fly by, even with the newer refrigerants like R134, there are ozone issues. That puts a lot of pressure on the auto companies to reduce use of it, maybe more so in Germany. Systems have shrunk way down in terms of total capacity. To cool same vehicle, these use like ⅓ of what they did into the 80's with R12. Thus loss of relatively minor amounts in absolute terms is a big percentage loss. From BTDT on my 2006 A8--any many other similar postings on the D3 board--once you lose about half the refrigerant by weight, it's all over. Total capacity on that one is 630g IIRC, and when it came up with 300g + as what was evacuated, it told me that missing 330 g or so was enough to take it out. That is one can or less of a lot of the store shelf can compressor grenades. First, system is sort of erratic and maybe feels humid, then it just drops off to nothing as far as my typical symptom experience. My sense from D3 is to expect charge life on these kinds of systems may be on order of 6 or 7 years, with no obvious leaks. If you have it charged and it flakes again after first working well, obviously have it leak checked with a uV dye. Or, have some put in preemptively as part of fill if desired.
Last edited by MP4.2+6.0; 09-24-2019 at 12:09 PM.