KNOWN ISSUE: A/C Wimps out on long runs
08-20-2015, 02:51 PM
#1
AudiWorld Super User
Thread Starter
KNOWN ISSUE: A/C Wimps out on long runs
Today I brought Dr. Strangelove in to the professionals, after the AC wimped out (got warm and weak) several times on a long road trip. Symptoms are that it is running fine, blowing strong and cold, and then after 3-4 hours in blazing heat and sun...it wimps out. Shutting the car down for 20 minutes helps restore it slightly. Running the heat and defrost on "cook" also helps somewhat. (And it feels so good when you stop doing that.(G)
But the point being, the AC system in a luxury car should not be wimping out on a highway trip, not unless the tires are also sticking to the pavement.
After the shop ran full diagnostics, they said the system passed all tests. BUT. They also have another customer who makes long weekly highway runs, who has had the same problem, and been able to repeat it. And that supposedly this is now a known issue to Audi of America, who supposedly will have a service fix of some type--once they figure out the root cause of the problem.
Meanwhile the problem is documented under warranty and I'm not holding my breath that Audi will just pick up the phone, call GM, and find out how to fix AC systems. I expect it is the evaporator icing up solidly, which is nothing new in AC systems that are a little bit off in design or adjustment.
So if anyone else has an AC system that wimps out on long runs...makes you wonder if maybe you've come down with the flu...or if the car is haunted by fire spirits...Nope. It is just Audi, gently taking their time to fix a flaw. DO add your voice to the choir, the more complaints they get, the more likely it will be fixed in this lifetime.
These systems seem to work just fine--until some 4 hours into heavy cooling loads. That's the point where they wimp out.
But the point being, the AC system in a luxury car should not be wimping out on a highway trip, not unless the tires are also sticking to the pavement.
After the shop ran full diagnostics, they said the system passed all tests. BUT. They also have another customer who makes long weekly highway runs, who has had the same problem, and been able to repeat it. And that supposedly this is now a known issue to Audi of America, who supposedly will have a service fix of some type--once they figure out the root cause of the problem.
Meanwhile the problem is documented under warranty and I'm not holding my breath that Audi will just pick up the phone, call GM, and find out how to fix AC systems. I expect it is the evaporator icing up solidly, which is nothing new in AC systems that are a little bit off in design or adjustment.
So if anyone else has an AC system that wimps out on long runs...makes you wonder if maybe you've come down with the flu...or if the car is haunted by fire spirits...Nope. It is just Audi, gently taking their time to fix a flaw. DO add your voice to the choir, the more complaints they get, the more likely it will be fixed in this lifetime.
These systems seem to work just fine--until some 4 hours into heavy cooling loads. That's the point where they wimp out.
08-20-2015, 04:41 PM
#2
AudiWorld Senior Member
Something is wrong and hopefully they'll find a fix for it. Ours runs plenty cold all of the time. We've taken several long road trips in the heat, as well as stop and go traffic with no issues at all.
08-20-2015, 05:39 PM
#3
AudiWorld Super User
Thread Starter
Bob-
Evaporators ice up for known and well-documented reasons, so there's no doubt something is wrong. Sometimes it is dirt clogging an evaporator orifice tube (internally). Sometimes it is simply a thermostat setting that is off, on an extremely humid day when the airflow isn't enough to keep condensate off the evaporator coils. (If they get a little dirt, dust, oil on them, that can build up and hold water.)
It is not the mystery Audi makes it out to be. Detroit got past this stuff long before they learned to build reliable cars. Ahem.
I'm just not willing to disassemble enough of my car to actually reach and inspect the evaporator, let alone tear down the entire system and check the electronics. I know the theory of how to do it, but actually DOING that all? Lord, there's a reason why AC repairs cost more than anyone wants to pay.
I wonder if anyone has actually "Lemon Lawed" a car because the AC had a glitch.(G)
GM cars always used to have a crotch blower, because Delco had learned from NASA and the moon missions that if you blow cold air on someone's crotch, it cools the blood in the femoral artery (among other things) and it makes the person FEEL cool and refreshed, more so than blowing air on most other places. Toyota and others have copied that, for ages.
Audi? I guess blowing cold air on the crotch is considered neoculturny, something a proper hausfrau certainly would never allow.(G)
'nother road trip coming up next month...and this time, there will be a witness riding along with me. And, my faithful old digital thermometer will be in one of the vents. Joe DiMaggio ain't the only one who knows how to play hardball.
Evaporators ice up for known and well-documented reasons, so there's no doubt something is wrong. Sometimes it is dirt clogging an evaporator orifice tube (internally). Sometimes it is simply a thermostat setting that is off, on an extremely humid day when the airflow isn't enough to keep condensate off the evaporator coils. (If they get a little dirt, dust, oil on them, that can build up and hold water.)
It is not the mystery Audi makes it out to be. Detroit got past this stuff long before they learned to build reliable cars. Ahem.
I'm just not willing to disassemble enough of my car to actually reach and inspect the evaporator, let alone tear down the entire system and check the electronics. I know the theory of how to do it, but actually DOING that all? Lord, there's a reason why AC repairs cost more than anyone wants to pay.
I wonder if anyone has actually "Lemon Lawed" a car because the AC had a glitch.(G)
GM cars always used to have a crotch blower, because Delco had learned from NASA and the moon missions that if you blow cold air on someone's crotch, it cools the blood in the femoral artery (among other things) and it makes the person FEEL cool and refreshed, more so than blowing air on most other places. Toyota and others have copied that, for ages.
Audi? I guess blowing cold air on the crotch is considered neoculturny, something a proper hausfrau certainly would never allow.(G)
'nother road trip coming up next month...and this time, there will be a witness riding along with me. And, my faithful old digital thermometer will be in one of the vents. Joe DiMaggio ain't the only one who knows how to play hardball.
08-20-2015, 06:30 PM
#5
AudiWorld Super User
Thread Starter
Dunno, Bob. This might be my last car, since the last one went 28 years and I hate to change what more or less works.(G) And I'm really hoping those self-driving cars will come into our lives. Yeah, I know, they're mundane. So what, they'll take me from here to there without arguing about anything. Sort of like a bus or train and undoubtedly better than a taxi...Amortizing out a million dollar taxi medallion is simply insane, taxis are way more expensive than a free market would support.
But you got me to thinking. Why would "this" Audi ice up when "that" Audi doesn't? Assuming both are in proper working order, and ignoring the environmental variables, which can be considerable. Like 100F and 100% humidity in the south recently, as against merely 99F and 90% humidity in the northeast.(G)
And it struck me: THE VENT SETTINGS. I'd never bothered playing with them, but while trying to beat the heat I saw all the options for which vents to have it blow through. I've got the four main vents blowing, but if I change that to "all", i.e. high and low, then the fan HAS TO BE SET HIGHER and that in turn will blow more air past the evaporator, which might be sufficient to keep the moisture OFF the evaporator and prevent the icing.
Going to make that change tomorrow, and see if it sticks and works on next month's road trip.
Could be that Audi put the evaporator coil fins just a tiny bot too close, allowing the moisture to collect, stick, and freeze up in very moist weather with "insufficient" airflow.
In which case the fix would be a redesigned evaporator core...and I'd really HATE to have that installed, because opening, purging, refilling, resealing, any AC system is more often than not a disaster in a few short years. And unless Audi is very progressive, the mechanics (and dealership) get underpaid for warranty work, compared to rack rates, so they tend to hurry it and cut corners.
By the way? A four-car incident caused me to have great appreciation for what our ABS/ESC systems can do for these lumbering beasts. So to be sure, I'm NOT unimpressed by some things Audi.(G)
But you got me to thinking. Why would "this" Audi ice up when "that" Audi doesn't? Assuming both are in proper working order, and ignoring the environmental variables, which can be considerable. Like 100F and 100% humidity in the south recently, as against merely 99F and 90% humidity in the northeast.(G)
And it struck me: THE VENT SETTINGS. I'd never bothered playing with them, but while trying to beat the heat I saw all the options for which vents to have it blow through. I've got the four main vents blowing, but if I change that to "all", i.e. high and low, then the fan HAS TO BE SET HIGHER and that in turn will blow more air past the evaporator, which might be sufficient to keep the moisture OFF the evaporator and prevent the icing.
Going to make that change tomorrow, and see if it sticks and works on next month's road trip.
Could be that Audi put the evaporator coil fins just a tiny bot too close, allowing the moisture to collect, stick, and freeze up in very moist weather with "insufficient" airflow.
In which case the fix would be a redesigned evaporator core...and I'd really HATE to have that installed, because opening, purging, refilling, resealing, any AC system is more often than not a disaster in a few short years. And unless Audi is very progressive, the mechanics (and dealership) get underpaid for warranty work, compared to rack rates, so they tend to hurry it and cut corners.
By the way? A four-car incident caused me to have great appreciation for what our ABS/ESC systems can do for these lumbering beasts. So to be sure, I'm NOT unimpressed by some things Audi.(G)
08-20-2015, 07:23 PM
#7
AudiWorld Super User
Per another similar prior thread, I suggest you try an easy fix if you feel like it is going to ice up on a longer jaunt. Just hit the recirc button. Then it doesn't need to keep dehumidifying the outside air and building up more water/ice. Plus it can keep the inside cooled down with less overall work.
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08-21-2015, 12:30 AM
#8
AudiWorld Member
^ This might explain why Audi chose to have recirculation off every time the car starts, no matter what's chosen in the car's mmi and ac settings.
None of my four Lexus automobiles did that.
None of my four Lexus automobiles did that.
08-21-2015, 04:02 AM
#9
AudiWorld Member
Per another similar prior thread, I suggest you try an easy fix if you feel like it is going to ice up on a longer jaunt. Just hit the recirc button. Then it doesn't need to keep dehumidifying the outside air and building up more water/ice. Plus it can keep the inside cooled down with less overall work.
I've spent my whole life using it most of the time for the a/c or heat. Less energy used, not allowing in foul outside air ...or whatever.
I thought I was supposed to !
08-21-2015, 06:17 AM
#10
AudiWorld Super User
Thread Starter
Recirc is a mixed blessing, although by using the (presumably) drier cabin air, that would also mean less chance of icing up the evaporator, so that could be another difference in cars and reason for the problem on some cars only.
Personally I prefer outside air, fresher, more air changes. Recirc traditionally gives you a colder cabin since it is starting with "conditioned" air, once the cabin cools off.
But since the 70s or 80s in the US, all auto makers have been required to push fresh air into the cabin at all times when the ignition is on, to prevent carbon monoxide poisonings from exhaust problems. You can't do that with recirculating air, you have to mix in fresh. Which is also why you can't ever quite get a car's fans to truly SHUT OFF if you are parked on a winter or summer day, and figured you could sit for a few minutes without losing cabin temperature. Ignition must be off to truly shut the fans.
The mode that the AC comes up in, varies by the car maker. Front vents, all vents, rear floor vents included or not, rear AC via the B-pillars...each one has their own ideas including whether to reset to defaults or keep your last settings.
But I'll be happy if "recirc + all vents" gives me a workaround on this, until Audi wakes up.
Personally I prefer outside air, fresher, more air changes. Recirc traditionally gives you a colder cabin since it is starting with "conditioned" air, once the cabin cools off.
But since the 70s or 80s in the US, all auto makers have been required to push fresh air into the cabin at all times when the ignition is on, to prevent carbon monoxide poisonings from exhaust problems. You can't do that with recirculating air, you have to mix in fresh. Which is also why you can't ever quite get a car's fans to truly SHUT OFF if you are parked on a winter or summer day, and figured you could sit for a few minutes without losing cabin temperature. Ignition must be off to truly shut the fans.
The mode that the AC comes up in, varies by the car maker. Front vents, all vents, rear floor vents included or not, rear AC via the B-pillars...each one has their own ideas including whether to reset to defaults or keep your last settings.
But I'll be happy if "recirc + all vents" gives me a workaround on this, until Audi wakes up.