[blacktone]

A while ago they had to remove my dash to fix my AC they replaced 2 blend doors about 8 months ago.The AC was coming out warm on the passenger side and driver side.So now 2 weeks ago the air started coming out warm on just the passenger side then went to cold again then yesterday back to warm then went cold.So I went to caddy they say its normal not sure about that they say the temp can change some its in some bulliten they gave me.Any thoughts on this?When they had my car the first time it took 2 weeks to get back someone messed something up and had to fix it never really got the full story on that.

 

[Melze]

Just from personal experience, incorrect and asymmetric temperatures on my 2016 which also remained un-diagnosed and "could not be duplicated" disappeared when my CUE was replaced.

 

[blacktone]

Just from personal experience, incorrect and asymmetric temperatures on my 2016 which also remained un-diagnosed and "could not be duplicated" disappeared when my CUE was replaced.

my CUE has been repalced 3 x already

 

[rsingl]

I bought my first first new GM vehicle in 1985 and almost all have had automatic HVAC systems. ALL have had wonderful HVAC performance EXCEPT for the ATS which would benefit from some holy water and a priest skilled in exorcising demons. Behavior/performance is inconsistent working wonderfully at times and very flaky at others. My 2018 GMC Sierra Denali and 2016 Corvette Z06 both have automatic climate control systems which work exactly as they should.

The ATS HVAC reminds me somewhat of the description of how GM accelerator position sensing/engine torque output works: the driver makes a request via the accelerator but the ECM determines how much torque will be developed based upon multiple operating parameters. So look at your interaction with the ATS CUE/HVAC system as a request to a disinterested waiter rather than an obedient servant

I believe after the person responsible for this system left GM he went over to Microsoft to develop Windows 10 which is equally annoying.

 

[RudyF6]

After several attempts at this very problem at a certain dealer I no longer patronize, I went to another a couple weeks ago. All I ever got was the typical "no problem found at this time" BS. New dealer was different - they couldn't duplicate my issue either (driver's side not cooling intermittently), but they went ahead and did an electronic update on the blend door/actuator/control system. It's only been a couple weeks, but seems to be working - haven't lost driver's side cooling since! As an added bonus I think my temp setting is much more accurate and repeatable now.

 

[sadpanda]

I started having this issue as well. My first thought was bad duct temp prob. I purchased a VXnano (GM MDI clone) and what I'm actually seeing is the duct probes are pretty much in spec (left to right is different but within X degrees so passes test).

In a different screen however, I can see the HVAC control module requests a certain position from the temperature blend door and at first, the stepper motor responds and reports back as being in the correct position (also duct temp changes correctly) but after a few minutes the reported position begins to climb and simply keeps climbing until the duct is essentially full hot. All the while the requested position never changes.

While typing this I just realized I forgot to see what the duct temp was reporting at that stage... Need to run the test again.

Anyway, if the duct temp is correctly reporting the raise in temp and the requested position is not changing its probably a bad Cue or BCM (which ever is in charge of actually handling the door functions not just the buttons).

Long story short, if the techs actually hook up the scanner and spend 5min in the car, they should be able to diagnose the issue. Its not like I found some easter egg menu in the MDI

 

[RedCadi]

I bought my first first new GM vehicle in 1985 and almost all have had automatic HVAC systems. ALL have had wonderful HVAC performance EXCEPT for the ATS which would benefit from some holy water and a priest skilled in exorcising demons. Behavior/performance is inconsistent working wonderfully at times and very flaky at others. My 2018 GMC Sierra Denali and 2016 Corvette Z06 both have automatic climate control systems which work exactly as they should.

The ATS HVAC reminds me somewhat of the description of how GM accelerator position sensing/engine torque output works: the driver makes a request via the accelerator but the ECM determines how much torque will be developed based upon multiple operating parameters. So look at your interaction with the ATS CUE/HVAC system as a request to a disinterested waiter rather than an obedient servant

I believe after the person responsible for this system left GM he went over to Microsoft to develop Windows 10 which is equally annoying.

I enjoy all of your posts. Most are over my head but I love the read.

This one had me laughing out loud! My CTS was/is similar. Two winters without heat on the driver side. My independent mechanic drove it for an unrelated matter. The passenger side was like a sauna.

Seems the SA took notice after I told him that my indy drove it. They recalibrated the doors. Now driver side is mostly comfortable. I'd hate to be a passenger.

I think the actual object of CUE was to finally rid Cadillac of all those terrible long time Cadillac loyalists who ruined the brand with exclusive Cadillac purchases.

 

[blacktone]

After several attempts at this very problem at a certain dealer I no longer patronize, I went to another a couple weeks ago. All I ever got was the typical "no problem found at this time" BS. New dealer was different - they couldn't duplicate my issue either (driver's side not cooling intermittently), but they went ahead and did an electronic update on the blend door/actuator/control system. It's only been a couple weeks, but seems to be working - haven't lost driver's side cooling since! As an added bonus I think my temp setting is much more accurate and repeatable now.

good read thanks my dealer says the same thing cant find anything at this time BS

 

[blacktone]

I started having this issue as well. My first thought was bad duct temp prob. I purchased a VXnano (GM MDI clone) and what I'm actually seeing is the duct probes are pretty much in spec (left to right is different but within X degrees so passes test).

In a different screen however, I can see the HVAC control module requests a certain position from the temperature blend door and at first, the stepper motor responds and reports back as being in the correct position (also duct temp changes correctly) but after a few minutes the reported position begins to climb and simply keeps climbing until the duct is essentially full hot. All the while the requested position never changes.

While typing this I just realized I forgot to see what the duct temp was reporting at that stage... Need to run the test again.

Anyway, if the duct temp is correctly reporting the raise in temp and the requested position is not changing its probably a bad Cue or BCM (which ever is in charge of actually handling the door functions not just the buttons).

Long story short, if the techs actually hook up the scanner and spend 5min in the car, they should be able to diagnose the issue. Its not like I found some easter egg menu in the MDI

thanks good info here much appreciated

 

[chockaday]

good read thanks my dealer says the same thing cant find anything at this time BS

This has been my experience as well, the dealer was trying to explain away something I was complaining about before even checking the car! These dealer shops are not very good on a lot of these things. I wish they would honor the work of an independent shop under their warranty, my own guy runs circles around the dealer shop that I go to.

 

[blacktone]

This has been my experience as well, the dealer was trying to explain away something I was complaining about before even checking the car! These dealer shops are not very good on a lot of these things. I wish they would honor the work of an independent shop under their warranty, my own guy runs circles around the dealer shop that I go to.

Well I am staying on top of this I called dealer yesterday and said we have to check further so we will see.if i have to go to another dealership to pay for the diagnostic test then I will then go back to mine for the warrenty work( long story )

 

[blacktone]

Update to the thread well came back from dealer for the 2nd time and they can not find a problem with my CUE or AC they say they checked with the scanner and come up with no codes. so in the mean time my passenger side of the car just will keep blowing out warm air when it feels like it.

 

[rsingl]

You can try dropping the passenger side temperature a few degrees and see if that helps things because as I stated earlier in the thread this HVAC system is full of glitches. I like to keep cars on the cool side (to the extent it is too cold for a lot of people). Set at 72 with both sides synced, my ATS is uncomfortably warm but setting it to 71 results in a very cool and comfortable car. Obviously a 1 degree temperature change shouldn't make a big difference and it doesn't in my other two GM vehicles but in the ATS it creates a stark difference.

I put my Fluke dual channel data logging thermometer on the counter so that I will remember to bring it with me next time I take the ATS out. I plan to put one thermocouple probe in one of the vents and the other in a shielded and shaded area near the console to log how much the air delivery and ambient temps are impacted by this one degree control input change. Just another of those sacrifices in comfort I am willing to make for science

Rodger

 

[angel71rs]

My way of dealing with the crappy ATS HVAC is to sync both sides LO and turn the fan up or down. Stupid to have to do this, but oh well. I much preferred the knobs and switches on my LS1 Camaros.