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Engine hot a/c turned off

I have a 2008 silverado 4.3L auto trans with 17,500 miles I keep getting a message that says Engine hot a/c turned off this happens after driving for about 15 minutes. All fluid levels are fine. Temp gauge was at about 195 and then as the message comes up the temp gauge dropped to baseline which is 160. I have disconnected the battery to clear it and its fine for about 15 min and then comes back. This is getting really frustrating

Roneb, There are a number of


There are a number of things that can cause the problem you are having. The most common is actually a faulty thermostat. If it sticks closed it can cause the engine to overheat (no brainer). What some people miss is a thermostat that sticks open or opens too early. This (the open thermostat) is most likely what's causing your problem. The engine doesn't heat up properly and the computer doesn't trust the readings it's getting so it goes into a failsafe mode. It turns on the light to warn you, turns off the gauge (because it doesn't trust it, if you will) turns off the AC to reduce tempuratures, and kicks the fans on. At some point (usually not the first time) it will set a code P0128 (coolant temp below thermostat regulating temp).

Here's what I recommend:

Check that the engine's cooling system is full and free of air pockets. I know you mentioned that the fluids are full but this is critical and worth double checking.

Check (when cold) to be sure the thermostat does not allow flow.

Allow the engine to heat up to make sure that it begins to flow.

Check trouble codes. Autozone will do this for free. Remember that it could take some time to set this or other codes but it's worth checking now. Please ignore them if they tell you the check engine light has to be on to check for codes and ask them to humor you. Tell them that some @$$hole told you to do so :-)

Get back to us with your findings. There is more to come. We may need to check for other issues like a faulty ECT (engine coolant temp) sensor, wiring/connection problems, computer problems, etc. but the other things should be checked first.

Please don't replace any parts until you get back to us.

Post back here with more info or questions on how to perform any tests. We'll be glad to help. Thanks.

Submitted by riverwarrior2010

Submitted by riverwarrior2010 Mon 01/23/2012

2008 Chevrolet Silvarado, 4.3 V-6 Enging with 63,000 mi. Engin hot A/C turned off warning light came on. Engine was not hot, check engine light not on, full of coolant and coolant flowing. Engine functioning normally. How do I get the warning light off?

Strikingly similar to the above wouldn’t you say? Are you back riverwarrior2010, but just callin yourself roneb this time around?

River or Ron,

Are you runnin Dexcool antifreeze? If you are then that's your problem, along with the possibility of an air pocket in the cooling system. Go to a quality auto parts store and buy a Prestone Flush and Fill Kit. The kit is designed to be permanently installed on the truck, and will get rid of any pockets. It simplifies flushing the system and any future flush jobs. Make sure you install and use the kit via the enclosed instructions. As far as what antifreeze to use? Use only the one that appears in the link below.

No I am not river, Thanks for

No I am not river, Thanks for the input Big Block I will try those things and get back to you. I have been searching for the answer to this for about a month and it seems to be all over the web. I think Chevy should recognize they have a problem here. I called the dealer to see if they were aware of such an issue and of course they played dumb and said bring it in we will check it out for you $100 just to check it out.

Roneb, Don't be fooled. These


Don't be fooled. These companies know what kinds of problems are out there. You have to consider the possibility of planned obsolesence. What I mean is that you may have worded it wrong. If it makes it out of warranty, who has the problem? Them? Nope! You! Remember the $100 you mentioned?

Big Block doesn't like Dexcool and I couldn't agree more. I feel that getting it out would be in your best interest, especially if it's never been flushed. I also like the flush kit he recommended and getting any air out of the system (like we both recommended) could be your solution but if the system hasn't been serviced and hasn't lost any coolant you should consider performing the other inspections first. They are very easy to perform and only take a short period of time.

Again, let us know if you need help with the tests. Thanks.

while it does have the

while it does have the dexcool it was changed when I bought the truck in October and since I purchased the truck I have only put 1k miles on it I will try burping it and checking the stuff you guys have recomended and will post my findings

Thanks again

Roneb, River's post was


River's post was mentioned and I forgot to leave you a link to it. You will see in the link below that it "fixed itself". That's HIGHLY unlikely considering the number of these that have issues (as you mentioned) and it will likely come back but you might wish to take a look at some of the info there (law suits, opinions, etc).

Thanks for keeping us posted.

It has gone away on its own,

It has gone away on its own, it didn't happen for 2 weeks and then came back.

Ron, (You Said)It has gone


(You Said)It has gone away on its own, it didn't happen for 2 weeks and then came back.

By any chance did it come back after a routine maintenance or repair was done? If the answer is yes, tell us the nature of that routine maintenance or repair.

No maintenance was done.

No maintenance was done. Just checking the fluid levels which are all fine when checked, and refueling.

Thanks for the response Ron.

Thanks for the response Ron. Try our suggestions and continue to keep us up to date.

So After having some warmer

So After having some warmer weather in my area I had no issues with the Engine Hot A/C Shut off then last week it dropped below 50 degrees and sure enough after driving for about 30 minutes it came back up. I took it to AutoZone to have them read the code and it came back with P0128 So I reluctantly took it to the dealer knowing that if it was the sensor or the ECM I was hosed, because my bumper to bumper was out. So they ran a diagnostic on it got the same code they troubleshot the ECM, the Coolant temp sensor and both were fine, so the checked the thermostat and found that it was faulty as most of you posted.
They said that the code comes on not because its overheating but because the thermostat opens too soon causing it to run to cool. Which I thought was weird for it to give an engine hot reading and actually be the opposite. So its been a couple of days now with the air temp outside around the mid 50's and I have had no trouble with it. The GM Tech said that he has replaced a ton of these thermostats on the 07' and 08' silverados mostly on the 4.3L engines yet when you talk to GM they are not aware of any issues... Go figure.

Thanks for all the help everyone that made suggestions much appreciated

Ron, Glad you got it figured


Glad you got it figured out, and that we were able to help. Thanks for the update.

My coolant temperature sensor

My coolant temperature sensor is showing up as a fault and the engine hot ad turned off shows up and my check engine light is on what does all that mean

When the engine is cool check

When the engine is cool check the coolant level in the radiator. Add if necessary.

If you need to add coolant then you know that there is a leak somewhere (check hoses and water pump for leaks and look for coolant leak around the engine).

If you haven't had to add any coolant (for a long time) then the coolant temp switch might be faulty.

Let me know about the coolant checks and if there is no leak I'll tell you how to check the coolant temperature sensor.


Please post the exact

Please post the exact computer code that your truck is displaying.

You can have it scanned at many auto parts stores for free. The post that code here for more assistance.

Submitted by roneb on Fri,

Submitted by roneb on Fri, 02/03/2012 - 14:18

What the hell is going on here?
What am I missing?

:-( :-(


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