Help me diagnose this -

This morning on the way to work the DIC flashes "ENGINE HOT A/C OFF". Odd, but the A/C has been cutting off in these cold mornings and unable to assist in defogging. Anyway, I looks at the temp gage and it is dead. Pull over check coolant level, it's ok. Electric fans are whizzing at turbo speed. Nothing looks, feels or smells overheated. Car runs fine.

After work, turn the key and get the "ENGINE HOT A/C OFF" warning. After sitting for 9 hours in 50 degrees. Hmm. Head for home. About 15 miles later the CEL comes on. OK. Once home get out the scanner - it tells me the reason for the CEL is the coolant temp is below the thermostat rating.

Putting this all together -
No engine temp gauge.
No AC
Conflicting diagnostics between DIC and OBD.

I say it's a sensor. Opinons? Anyone change the sensor on a 3.5? Autozone's help says remove a crosspipe, Hanynes says no crosspipe to contend with.

 

You could also have a failing thermostat. The new cooling system that the 3.5L has is not that fun to work with haha

But I also agree that it sounds like a coolant sensor causing the car to go into a fail-safe mode. Perhaps you should replace both?

 

My car had the EXACT same simptoms early on in it's life (like 20,000 miles, under warranty) I was up in Reno, 17 degree's outside, start my car, ran for all of 2 min and the it said Engine Hot/ AC off. Took it to dealer, and they replaced the thermostat, all was good after.

 

Got off work at a decent hour, when there is still light out. Sensor is down in the valley of pipeage next to some darned hot exhaust pipe, doesn't look to hard to get to but not real easy.

I'll try and get the t-stat replaced this weekend. By a shop. Down to one car and can't afford to muck something up.

Thanks all.

 

Can you please keep this updated as to what is going on. I also had a similar situation but haven't had anything done to it yet. Thanks

06 Monte overheated today.... ( 1 2)

 

Thermostat changed.

Couldn't believe that the shop I simply went in late in the day to ask about it stayed open and did it. I always go there and know that regular customers get some breaks but WOW.

T-stat had a seal/gasket in it's internals that was damaged and may have kept it stuck open. A code reset and things are back to norbal. No DIC warnings, temp gage works.

Will report back tomorrow.

Shop is Marina Tire & Auto Repair - Marina, CA btw.

 

Do you think the t-stat was the original one installed or has it been changed since you have owned the it?

 

Hard to say, the motor is a transplant that had 50K on it when installed earlier this year.

It looked clean, not my recollection of a thermostat coated in crusty deposits from various Japanese cars I've had.

 

That is EXACTLY what happened to my thermostat that went bad...the internal seal was keeping it open. Glad it was a simple, easy fix.

 

Well, call me a believer in the "it's the thermostat" club. This morning was another 37 degree morning, and at the same point where the warnings would go off it was as if it never happened.

Temp gage went to exact center position and stayed there. Previously it would get to one tick below center and die, send warnings, turn fans on turbo boost, etc.

My guess is that ENGINE HOT/AC OFF and a CEL gets sent with any coolant fault.

Back to wrapping presents...