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Please help...........driving down the road and temp gauge fell to cold and ac quit blowing cold.......car runs fine and no check engine lights......fan blower still bows but no ac or temp gauge working,,,,,,,please help....thx
 

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Please help...........driving down the road and temp gauge fell to cold and ac quit blowing cold.......car runs fine and no check engine lights......fan blower still bows but no ac or temp gauge working,,,,,,,please help....thx
Do you mean the engine coolant temperature gauge or the HVAC temperature gauge?
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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With a 2LT I assume you have manual temperature control so there isn't a temp indicator for the HVAC, right?

So if I understand right, only the coolant temp gauge on the far right of the dash pods fell to Cold (like the car hadn't been running) and the AC no longer blows cold air and the rest of the gauges work just fine. Is that correct?

The coolant temp gauge gets its input from the BCM and the AC gets told to do its thing there as well. You could have anything from a dirty connector ("fretting") to a failed BCM. And don't discount that you may have run over something that kicked up into the engine bay and damaged some wiring, or you might have had a critter get cozy and start chewing things. Do you ever park out in the rurals?

Does the fan even blow air? When you press the AC button do the fans at the radiator both turn on? (Engine must be running to test correctly.)
 

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Yes......you are correct.....the coolant temp gauge is on c and the rest of the gauges work fine.....fans do come on at radiator when I push the ac button......what is a BCM......please help.....
 

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BCM - body control module

It is a computerized device that accepts signals from various inputs and makes other devices turn on or off as programmed.

If the fans come on but the AC doesn't get cold, you might have a failed refrigerant switch or AC compressor clutch, but first I'd check the wiring. If you're comfortable doing so, unplug the pressure switch and jump across it. If you do and the AC turns on then the switch is bad - if AC doesn't turn on then you may have a blown fuse or damaged wire, or worse a BCM failure.
 

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OK guys.........got it fixed........popped of console panel and checke all fuses and connection to BCM and fuse box......still no gauge or ac......checked all fuses under hood and still no coolant gauge or ac........finally checked the battery and the ground connection was covered with build up....alot.....pulled battery teriminals off and cleaned real good......hooked back up and hooray......temp gauge and ac started working......a few questions......I have been noticing lately that the radio would not come on for a minute or two after I started driving.......also.....the car would want to stall very occassionaly at a red light but never quit.....could this corroded battery terminal caused these issues.......and why did the temp gauge and ac only stop working.....I am pleased it appears to be fixed but would just like to know for future reference......I am not sure if cleaning or the time I had the battery cable off reset the computer but it is fixed for now and I my wife is happy once again.....any more feedback on this is appreciated......
 

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.could this corroded battery terminal caused these issues.......

or the time I had the battery cable off reset the computer
Yes, absolutely. If there really is another problem, it will be back.

Next, you should have the battery tested.......as the bad connection might mean that it wasn't charging properly. If it is over 4 years old, you might want to consider a replacement.
 

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So I understand......the BCM could not have been getting enough volts at times and caused certain things to stop working?
 

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So I understand......the BCM could not have been getting enough volts at times and caused certain things to stop working?
Yes exactly.

The odd thing is.......with all the different electronic stuff on the cars these days, a low voltage condition like that might have different symptoms on somebody else's seemingly identical car.

It is becoming more and more difficult to diagnose something from only a description of the symptoms, even if the description is accurate, which it often isn't.

Many times a little $10 multi-meter can go a long way to eliminate the "easy" stuff.
 

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The gauge works like this:

The ECM receives the input from the ECT sensor & passes that on to the BCM which in turn passes it on to the instrument cluster. The weakest part of that chain tends to be the engine-mounted sensor itself & its wiring. But a breakdown can happen anywhere in that chain. My money is on an intermittent sensor or its circuit.
 

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....I have been noticing lately that the radio would not come on for a minute or two after I started driving...
Are you saying the audio takes that long before you hear it when tuned to a AM/FM station? Or are you referring to the radio display?
 

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Yes...........so far the problem is fixed......................thanks for everyone's help.......hope I can return the favor some day................
 

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The gauge works like this:

The ECM receives the input from the ECT sensor & passes that on to the BCM which in turn passes it on to the instrument cluster. The weakest part of that chain tends to be the engine-mounted sensor itself & its wiring. But a breakdown can happen anywhere in that chain. My money is on an intermittent sensor or its circuit.
Under normal circumstances you would be right. The ECM provides both power and ground to the ECT which is a variable resistor so when system voltage starts dropping (which is a result of corroded battery terminals) the temp readings are incorrect and since system voltage is low the ECM cannot read them correctly either. That could cause the gauge to drop to cold since the IP gets its data from the BCM which gets it from the ECM.

The ECT isn't directly part of the A/C control logic since it only feeds the ECM. The ECM turns the compressor on and off based on several inputs but it isn't clear that low coolant temp is one of the reasons it would not allow the compressor to run.

However, the Ambient air temp sensor feeds the BCM which interfaces with both the HVAC and the ECM. The BCM provides the voltage source for the ambient air sensor so low system voltage would affect its accuracy as well. The SM clearly shows the ambient air sensor is involved in the compressor control logic.

The OP also mentioned some other weird things happening which can be attributed to low system voltage.

The preponderance of the evidence indicates the corroded battery terminal was the culprit.

Bill
 

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Yes...........so far the problem is fixed......................thanks for everyone's help.......hope I can return the favor some day................
So the "the car would want to stall very occassionaly at a red light but never quit" & the "I have been noticing lately that the radio would not come on for a minute or two after I started driving" issues are now resolved as well? Or is it too early to say?
 

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Under normal circumstances you would be right. The ECM provides both power and ground to the ECT which is a variable resistor so when system voltage starts dropping (which is a result of corroded battery terminals) the temp readings are incorrect and since system voltage is low the ECM cannot read them correctly either. That could cause the gauge to drop to cold since the IP gets its data from the BCM which gets it from the ECM.

The ECT isn't directly part of the A/C control logic since it only feeds the ECM. The ECM turns the compressor on and off based on several inputs but it isn't clear that low coolant temp is one of the reasons it would not allow the compressor to run.

However, the Ambient air temp sensor feeds the BCM which interfaces with both the HVAC and the ECM. The BCM provides the voltage source for the ambient air sensor so low system voltage would affect its accuracy as well. The SM clearly shows the ambient air sensor is involved in the compressor control logic.

The OP also mentioned some other weird things happening which can be attributed to low system voltage.

The preponderance of the evidence indicates the corroded battery terminal was the culprit.

Bill
I find it curious that OP did not have an engine start or headlamp complaint. Nor did all four of his complaints appear simultaneously. At least that's how I interpreted his posts. But maybe we just didn't get the complete picture that would fill in those details. I'm going to try taking my ECT sensor offline & seeing what happens to my A/C, if anything. I'll get back with the result.
 

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I find it curious that OP did not have an engine start or headlamp complaint. Nor did all four of his complaints appear simultaneously. At least that's how I interpreted his posts. But maybe we just didn't get the complete picture that would fill in those details. I'm going to try taking my ECT sensor offline & seeing what happens to my A/C, if anything. I'll get back with the result.
Yeah, I was filling in the blanks to some degree. Sort of what you have to do with posts on the internet.

I can't say what will happen with the ECT although I suspect if you could rig it to give a high temp the A/C would shut off. From personal experience I know that when the ambient air sensor is stuck on a low temp the A/C will not work.

Bill
 

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I'm going to bet money that it isn't fixed. It might work fine for a few days to a few weeks, but I'm betting it will reoccur. Here's my similar story.

I had the same problem with my '09 2.4L LT2. It was intermittant. The wife drives the car daily. She complained that the a/c would not work on occasion. Every time I drove it (mainly on the weekends), it always worked. Finally it acted up on me, but was very intermittant. Maybe once a week it would quit. It was mainly inop during startup, then would start working somewhere during the trip. I told the wife if it ever stopped working while she was on her way home from work to bring it by my dealership. One day she did, and of course it started working as soon as she pulled in. Check the pressures, all good. Went ahead and did an evac and recharge. Still acted up a few days later. Went ahead and changed the pressure switch. Again, acted up a few days later. Took it to the Chevy dealership and let them have it for a couple days, of course, didn't act up. Most of the time, if you would turn the car off and back on, it would start working again. Finally, after fighting it for months, I got a check engine light for a thermostat code. After some research, I found that the code (I forget which one) could be fixed by the thermostat and/or the coolant temp sensor. I purchased both in the fall, but have yet to install them. It did act up once a couple months ago, but haven't had any problems really yet this year other than that one time. Eventually I'll get around to changing both of them out. I'm just lucky with all of the 90+ degree days we've had this year it has worked.
 

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OK guys...........this is Cardinal 86 (original post question)...........the car stayed fixed for a couple of days and driving down a smooth hwy the a/c quit cooling and the collant hand fell to cold............everything else works fine and car runs good.........your discussion is helping me..........could it be the thermostat and/or coolant temp sensor as mentioned is previous post.......must be something that the ac and coolant temp are both connected to since they both stop at the same time........please help again.......thanks
 
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