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Discussion Starter #1
2010 malibu ltz
i was driving down the highway today and my temp gauge was working fine, then of a sudden was stuck on cold which causes the ac not to blow cold. when i got to work, i waited a few hours then went to check it out and everything was working fine. everything was fine for about half of my 25 mile commute home, then quit working again. any advice before i overpay at the shop? i can do a lot of work myself, but it’s a little difficult at 8 months pregnant.
 

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A guess over the inter-webs is....
The engine temperature sensor or associated wiring is failing causing the temperature gauge to drop to zero and the Engine Control Unit/computer/module is shutting down the AC to protect the engine. The engine temperature sensor is a common failure and is relatively inexpensive to have replaced. Again this is a guess.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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Which engine do you have?

If the ECT (engine coolant temp) sensor tells the ECM or BCM (engine or body control modules) that the coolant is cold, the needle will swing to C but the AC will still work. That's not what's happening. If it stops reporting the temp, then it goes into fail-safe mode and sends the needle to C and disables the AC. It should also turn both fans on High, but that's hard to tell unless your window is down or the hood is up.

On the 3.6L V6, the ECT is right on top and easy to find and replace.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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I tried watching that but couldn't finish.

Too much jumping around and movement; I started getting a headache.

Also, pliers??? to remove a 10mm nut? Come on, dude! And a 3/4" wrench to remove a metric-sized sensor? It's either a 17, 18, or 19 mm.

But, so long as it works and fixes the issue, it doesn't care what tools were used.
 

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A guess over the inter-webs is....
The engine temperature sensor or associated wiring is failing causing the temperature gauge to drop to zero and the Engine Control Unit/computer/module is shutting down the AC to protect the engine. The engine temperature sensor is a common failure and is relatively inexpensive to have replaced. Again this is a guess.
Thank you for sending me this. Gonna give it a go tomorrow or this week to come.
 

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Swapped out the coolant temp sensor and still no ac. Compressor replaced and is getting juice but clutch won’t engage. Also noticed my fans aren’t turning on at all so going to replace the relays and see if that’s hopefully the issue. No check engine light either.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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If you have an OBD reader that can watch live data, monitor the coolant temp. If the ECM and/or BCM is not getting a signal, then the issue is likely not the sensor but the wiring.
 

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Checked the wiring and thankfully all was good. I switched out the 2 engine coolant sensors (on the right side of the engine by the water inlet and the other on the side of the radiator above the drain plug) and replaced the thermostat housing that has the sensor attached this morning. AC is working for now.
 
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