Engine hot a/c turned off

[Richard Kerkau]

My 2008 Sierra 4.3 randomly gave a false engine hot a/c turned off indicator. After research on web and much frustration I am pretty sure I solved my problem. Just like most the searches indicate, I replaced the thermostat and engine coolant temperature sensor and connector. At first this did not work and I still got false indicator. After further research I discovered the parts house gave me a 180 thermostat instead of the 195. With the 195 my engine heats up to normal running temp (just under 210) and no more false indicator. Bottom line is make sure you get the 195 thermostat and not the 180.

[Dino Gravessi]

Just following up on Richard's post about the 195 thermostat.  This is the solution!  If a lower temp thermostat is used it takes too long for the engine to warm up and the computer sees it as a problem, but it looks like there is no error message for "Engine cold" and it uses "Engine Hot / AC turned off" instead.  Very misleading and GM should fix this.  It takes about ten minutes after cold start for the error message to display and will occur more often with colder ambient temperatures (winter).

 

You MUST use a 195deg thermostat.