[xFantasyFiendx]

Thanks. Well I unhooked my battery, it reset the code and my A/C is working again. Something i've recently noticed, i can use my heat no problem, but if i have my AC on, my temperature gauge raises from the C to half way. And yesterday just driving out of my drive, a loud, fast click sound started coming from my car, but if i slide my temperture toward heat it will stop. But after driving with it with cool air going, it did eventually stop, but what could that be?

 

[systemcheck2006]

i read somewhere that it could be an actuator, did you have it set to recirculate?

 

[lotsofspareparts]

Sorry to reincarnate this old thread. I have had the same issue with my 07 3.9 LT as well. I have replaced my temp sensor twice (first with an AutoZone part, and then with AC-Delco part) and still have the same issue.

I am starting to think I do have a problem with my thermostat since it takes almost 15-20 min of driving through my 35 mile commute for the car to warm up to just below the middle of the gauge, and will stay there till it throws "Engine Hot/AC Off".

I will replace my thermostat and get back to this post and provide an update.

 

[systemcheck2006]

did they same, the dame thermostat gasket was half there, last time I listen to that mechanic.

 

[lotsofspareparts]

Gonna swap out the thermostat and spark plugs today since I am close to that 100k mark. After a preliminary inspection of the engine compartment it appears the thermostat housing is on the front lower portion of the engine where the lower radiator hose connects. Can someone confirm this for me, and provide an estimate of how much coolant my system holds (07 3.9).

Thanks guys.

 

[lotsofspareparts]

Swapped out plugs, not the easiest set of plugs I have changed, but not the most difficult either. As I expected my thermostat looked just like everyone else has described, rubber gasket in the middle was mangled and sticking halfway out. Plugs made a big difference in performance, and on a funny note the plugs in the front were in worse shape than the plugs on the backside. Hmm, maybe the rear bank of cylinders are the ones that shut off in 3cyl mode.

 

[tarnel]

I have an 06 3.9L with this same issue. Going to take a look at and probably replace the thermostat and do a coolant flush this weekend. Hopefully it fixes the issue! Thinking about doing plugs soon too but I don't know much about what brand to get. What plugs did you use lotsofspareparts?

 

[kingnutin]

Delco and ngk are both very good, just make sure you get the iridium plugs, it's designed for them.

 

[tarnel]

Thanks for the tip on the plugs!

I replaced the thermostat 2 saturdays ago, cleared the check engine code and have yet to see any more issues. Sure enough the seal on the stat was about half gone. Yay! I can remote start my car again!

Gotta say replacing the part was pretty easy. Will probably end up taking the car into a shop for a full coolant flush and replacement tho. To much of a pain to get all the coolant out of the block.

 

[Oldchevyguy]

2006 Impala Engine Hot Issue

In reading some of the posts regarding false messages indicating an Engine Hot message (and subsequent Engine Hot/ Turn AC Off) displays, I experienced exactly the same thing with my 2006 3.9 LTZ. One night driving home from work, I got an Engine Hot message and thought "HOLY CRAP!". Shut the car down. I happened to have about a half gallon of Dexcool in the trunk, poured it into the coolant reservoir, started the car and drove a short distance to home. Next morning, checked the coolant level in the reservoir and it nearly full before I started the car. Drove about 2 miles and got another Hot Engine message. Stopped, raised the hood, and put my hand on an engine that was barely warm!!! So I thought...Hmmm, engine is NOT hot
and this is obviously a false message!!

Drove on to work and kept my eye glued to the temperature guage. I did notice that the temperature would swing upward at times but it remained at a higher temp than the usual halfway point between cold and hot.

When I got to work (at AutoZone) I talked with a buddy that was a true SAE certified mechanic. I suspected temperature sensor and he concurred. Bought a new temp sensor, installed it, and everything back to normal since. Note: had to pull off the top 'cover' of the engine as well as a small section of exhaust cross-over pipe the access the sensor. Really was not too bad.

Also noted posts of 'fluttering' or rapid tapping noise when (and ONLY when) changing the temperature settings. Lasts about a minute, etc.
Mine does it too. I know I need to replace the air blend control but have not got around to it yet.

Good to know that these issues are relatively common.

 

[jw06]

Engine hot AC off - again

Two weeks ago I got the "Engine hot AC off" message and the temperature gauge went to cold. After reading these post I replaced the temp sensor and all was well until last night when the message came back. Could this be a thermostat too or could the sensor be bad after two weeks?

 

[kingnutin]

Might be the pigtail for the sensor.

 

[Ejbiers]

Problem solved!

I had the same problem and it was my thermostat. I took the thermostat out and the rubber seal to seal the thermostat when its closed(not where it was sealed into the engine) was keeping the thermostat open all the time. If you let your engine hot a/c off message go long enough you will get a check engine light and a code(i forget the code) but the code will be the motor is taking too long to warm up (because the thermostat is stuck open and constantly flowing coolant through your motor instead of opening the thermostat and allowing coolant to flow only when your motor reaches 180degrees).

Do not try to pop your thermostat out and fix the seal it is most likely stretched out and shot and even if it wasn't it will still be damn near impossible to try and fix it. just spend the $22 for a new thermostat. The OEM thermostats are cheap and garbage which is why this is a common problem and alot of GM vehicles from pickup trucks to suvs to cars.

The reason you don't get a check engine light right away is because the car taking too long to warm up is not good for the car but its not gonna destroy the car. It will put a pending code on the computer though it just takes some time for the code to register.

Also the temp gauge on the newer cars are not a real representation of the temp. It is a estimate of where the car should be at that point in time. So all the computer does when that message appears is shut down your temp gauge (your motor isnt really that cold). People would freak out when they saw how much the temp gauges would fluctuate when driving so the car markers made the temp gauges 'artificial' so people wouldn't worry so much.

Hopes this solves your problem or at least gives you some insight on it!:beer:

 

[systemcheck2006]

+1 for post

 

[dalejrfan88]

+1 for post

I had the low coolant loss on my 07 3lt with the 3.9 but never got the "engine hot" turns out my 3.9 was eating coolant due to a bad coolant crossover pipe and poor headgasket and intake gasket...even when i was looking at several used models i noticed that the 3.9s and 3.5 always had very little coolant at the bottom of the resevoirs. Now i see in 2012 they finally went with a more sealed resevoir that is filled to the top:gaah:

 

[Impala_Ken]

I realize this thread is long cold (no pun intended), but just thought I would add my experience on my 2006 3.5 VIN-K. I got the same mystery message "Engine Hot, A/C Off" one day a few weeks ago, I thought I had overheated and ruined my engine (never heard a warning chime, maybe because my driver door speaker had recently failed). I thought I had ruined my engine, but the heater was working fine and the engine seemed okay. The temp guage stayed pegged at "C" through several warm-cool cycles, so replaced the sensor (had to remove driver-side upper motor mount and small coolant pipes to access the sensor. Problem went away (probably due to battery disconnect) for several weeks and through a long 3300 mile vacation, but came back last week. This time I replaced the thermostat since it appeared the observed engine temp varied between 185 and 203 degrees and figured maybe it was sticking (never had my analyze with me when the code would post). Has been quiet since, but won't know for sure for a few weeks. Old thermostat looked perfect, but I have 208K miles on this car.

 

[Impala_Ken]

Side note: the electrical info in Chiltons seem to indicate that the temp sensor is routed to the Power Control Module and Body Control Module before it goes to the temperature guage. I find it odd that when we get the "Hot Engine, A/C Off" message that the control modules seem to shut the temp guage off. Is there a flash fix for this???

 

[463]

Hi Ken. when the "Hot Engine, A/C Off" message is on the computer is programed to shut the temp guage off. Is there a flash fix for this? Non that i know of.
The "t" stat can be checked with a thermometer and a pan of water as the temp rises to 195oF the t stat should open smoothly and close when removed fron the heat.
The temp gauge in the car should come up from cold to lets say sit at 1/2 way and stay at that point, at this point the t stat is controling temp and the cooling fans the take over the rest of the cooling as the cooling demands increase.
make sure the cooling recovery tank is at the full cold when the engine is cold, there is a chance the new temp sender is messed up or there is air in the cooling system.
A weak rad cap will also mess with the temp as the psi is to be at 15 lbs then the cooling system is working.

 

[Impala_Ken]

Thanks. This also may be old news, but when replacing the thermostat I did not follow my instincts and used the thermostat housing torque specs in the Chiltons instead (which is the same as the Factory Service Manual). When I heard the bolt fail I knew I should have waited and looked for a bulletin. Fortunately I had only stretched the bolt and there was enougn metal remaining and I could back it out. Could have been much worse. The thermostat seal is only a rubber O-Ring, I could have done it by "feel'.

For the V6, the stock manuals I have found specify 18 ft-lbs, which is WAY too much for M6 screws. Using the "Just Answer" web-site I paid an online mechanic to look it up and he found the following Bulletin which corrects the torque for V6 (covers 2006 -2008, I believe - did not see the Bulletin).

07-06-02-007 NOV 07 Engine - Revised Thermostat Housing Bolt Torque ​

New specs: 7.4 ft-lbs, or 89 in-lbs.

I was guessing 8, within the range for an M6x1.0 bolt ( 7 - 9 ft-lbs).

 

[TxImpala89]

I got my struts replaced today (i know this has nothing to do with it) but i down the street from my house when the "engine hot/ac off idle engine" message came on the display and the temp gauge shot up all the way to the top to red! i pulled into my place and it went down to normal temp and the message dissapeared along with the continuous warning chime (all withing 2 minutes) what should i look into?