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Discussion Starter #1
Hi, All,
Sorry, this is both an AC issue and now a check engine issue (maybe directly related). Unfortunately this started Saturday evening and so there are no shops open until next week to take a look at it.
Summary of the issue:
2015 Enclave 66k miles. All of a sudden the AC cut out while driving. Trying to turn it on again resulted in the AC button flashing 6 times. The AC would run shortly after starting the car again but then cut out. Eventually the check engine light came on as well.

Any ideas?
Thank you!
 

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Unlikely they’re related since the OBD system (the one that sets the check engine light) doesn’t monitor anything having to do with the AC system. The AC working when you first turn it on but quitting probably means it’s low on refrigerant. When the computer sees the low pressure it disables the system to protect it and flashes the light 6 times.

I’d start by getting the CEL scanned. Autozone is open and they’ll scan it for free.

AC I’d start with a good general mechanic that could test to see if it’s low and check for leaks.
 

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Discussion Starter #3 (Edited)
Unlikely they’re related since the OBD system (the one that sets the check engine light) doesn’t monitor anything having to do with the AC system. The AC working when you first turn it on but quitting probably means it’s low on refrigerant. When the computer sees the low pressure it disables the system to protect it and flashes the light 6 times.

I’d start by getting the CEL scanned. Autozone is open and they’ll scan it for free.

AC I’d start with a good general mechanic that could test to see if it’s low and check for leaks.
Wow, great tip! Thanks. I didn't know autozone did that for free.

I just took it there and they found out it was faulty engine coolant sensor.
They thought it's possible the car was thinking it's overheating and shutting the AC off as a precaution.
Is an engine coolant sensor an easy fix or is that best left to a mechanic?
Thanks again
 

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Oh yeah, There was another poster recently with the same problem of the 6 blinks and the problem was the temperature sensor. There are a few youtube videos on the replacement procedure.
I am wondering if mine is going bad, last week it took several minutes before the A/C got cold, I didn't notice any blinks, it was a solid light but one symptom is the cooling fans will keep running for quite some time after the vehicle is off. My battery was dead this afternoon. And I just got Rockauto order today. :(
 

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Discussion Starter #5
Oh yeah, There was another poster recently with the same problem of the 6 blinks and it was the temperature switch. There are a few youtube videos on the replacement procedure.
I am wondering if mine is going bad, last week it took several minutes before the A/C got cold, I didn't notice any blinks, it was a solid light but one symptom is the cooling fans will keep running for quite some time after the vehicle is off for a while. My battery was dead this afternoon. And I just got Rockauto order today. :(

All right, I replaced the engine coolant sensor and things seem to be humming again. For the record, I also had the battery replaced since it was struggling to start these days, too (5 year old battery + heat wave). But I'm thinking it was still the sensor that did it.
If the issue comes back, I'll update.

Thanks for the help!
 

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Now I'm really curious if the ECU is smart enough to disable the AC if detects a cooling system problem.

If the battery was bad it's very possible there was nothing wrong with your coolant sensor though. I've seen all kinds of different codes get thrown incorrectly because of a bad battery. Most sensors are just measuring if a resistance is within a specified range and resistance is directly tied to voltage. A low battery can push that resistance out of spec and incorrectly trip a code.
 

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When the AC is blinking did the car measure the outside temp? If it does not than I have a solution for that.
 

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The ambient temp sensor harnes goes to a conector on the passanger side near the fuse box. You have to measure pin to pin the wires from sensor to that connector and if one of them connection is missing you have to bypass the original harness. To repair the original harness it will take you much longer as you have to undo the harness, because sensor wires get connect with other cable as single one.
 

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Discussion Starter #10
When the AC is blinking did the car measure the outside temp? If it does not than I have a solution for that.
Sorry for the late reply, the car was measuring the outside temperature (usually around 100F ;) )
 

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Temp should change depending on weather. If it staying allways same start by changing the sensor of outside temp first. Is located at the front bumper.
 

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Now I'm really curious if the ECU is smart enough to disable the AC if detects a cooling system problem.

If the battery was bad it's very possible there was nothing wrong with your coolant sensor though. I've seen all kinds of different codes get thrown incorrectly because of a bad battery. Most sensors are just measuring if a resistance is within a specified range and resistance is directly tied to voltage. A low battery can push that resistance out of spec and incorrectly trip a code.
Jay, I believe almost all late model vehicles will shut down the A/C if the coolant temp exceeds a certain threshold. The engine ECU monitors a lot of systems, especially anything that could cause engine damage.
 

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Sorry for the late reply, the car was measuring the outside temperature (usually around 100F ;) )
Is your issue still resolved, no more A/C problems? The coolant Temp sensor and Battery replacement took care of it?
 

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Low or inconsistent battery voltage can cause a lot of issues that people don't associate with the symptoms. That being said, anytime you encounter any type of issue, check your battery and cables BEFORE you look any further. Also check all related fuses and relays in the suspected circuit. I think I related prior about the person that replaced a $1000. ECU for a faulty fuel pump relay.
 

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All those Dealer Mechanics who would rather throw parts at a problem rather than do basic troubleshooting.....
 

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All those Dealer Mechanics who would rather throw parts at a problem rather than do basic troubleshooting.....
That is one of the luxuries of working at a dealership. An independent shop can't return electrical parts if they don't fix the issue. Most tech's at a dealership have a supply of parts or grab one from the parts department to see if that fixes the problem.
 

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OK, I admit I have a supply of parts at work and sometimes changing a suspected part is the easiest and fastest way to see if that was the problem, of course I don't always know if the replacement is good.
 

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OK, I admit I have a supply of parts at work and sometimes changing a suspected part is the easiest and fastest way to see if that was the problem, of course I don't always know if the replacement is good.
At a dealership, a tech can usually lay his hands on a known good part, which makes diagnosing a lot easier. The problem with ECU's (Control modules) now days is that they require programming and once they are programmed to a vehicle, they can't be programmed to a different vehicle. One shot and they are done.
 
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