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Discussion Starter #1
Hey folks, been awhile. The other day wife is driving home from work, AC stops cooling all of a sudden, AC dash lights stayed on, just air got warm. Next day driving to work, "engine" light is on, she scrolled through info, coolant reads nothing. Her boss checked under the hood, sees coolant reservoir is low, adds about a cup he says of coolant, later I find out this was 50/50 GREEN.(EG) I drained the system today & poured through distilled water, then closed & filled eith 50/50 DEXCOOL. Ran the motor & heat/defrost for awhile thinking the engine would suck it in at some point & I could top off reservoir. After about 45 minutes or more, I gave up, reservoir never droped & hose was just a little warm. Radiator fan ran the entire time, I thought it was supposed to go on & off, never stopped. Sorry if I is ignant, just trying to keep the work vehicle running? Any thoughts from the Cobalt pros? TIA
 

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Discussion Starter #3 (Edited)
Code is P0128, says thermostat, is that definitely it? Shows dashes in "---" in coolant display (DIC). Thanks for the thoughts BB.
 

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Check the connection to the temperature sensor first. Chances are thermostat is still good.
 

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Discussion Starter #6
Believe you're right C7, replaced thermostat, no change. Going to replace sensor now. Would sensor make radiator fan run when starting the engine?
 

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Discussion Starter #8
Well, after install of coolant temp sensor, ran the engine for awhile with defrost, DIC coolant temp started working, & AC cooled again.(YEA!) Took it for an extended test drive on city streets & the freeway, temp never exceeded 199f with defrost on. Seems to be ok. Tried to clear codes to turn off engine light, but is still on. Will if go off by itself?
 

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Discussion Starter #12
anyone, anyone?
ac stops working, DIC coolant display shows "---", had a code p0128
replaced thermostat, DIC shows "---", still a code p0128
replaced coolant sensor, DIC reads correct(all under 199f), still p0128, now p0118 also
I don't know what else to do but take it to the stealership, we don't have any money for this, democrats took care of that.
 

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Discussion Starter #15
do not have the "---" anymore, reads what appears to be an accurate temperature. Just can't get rid of p128 & p0118. How do I bleed the system?(thanks for the tip Tred07)

---------- Post added at 05:34 PM ---------- Previous post was at 04:34 PM ----------

She just got home, says engine light is off (woohoo!) Do you even need to bleed a closed coolant system? I ran it for awhile with the reservoir cap off, kept expecting the level to go down, but it never did. I guess it's ok, at least for now!!! I do really want to thanks all who pitched in to help, hope you guys have a great week!
 
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