BULLETSSMOKE

Ok the thermostat has been replaced and I have full functionality back again. Thanks SunburstSS. But the 2nd part of my problem is my A/C. Somebody said that if the ECM doesnt "trust" the thermostat then it will cut off the A/C. Well now that my thermostat works again, how can I get my ECM to regain "trust" to the thermostat so I can have my damn air conditioning back?

Sunburst_SS

no problem....glad I could help.

a/c should work if you cleared the codes from the ecm.....unless there is another problem w/ the a/c system

BULLETSSMOKE

how am i supposed to clear the codes? i sure as hell know autozone wont do it

Sunburst_SS

try disconnecting the battery for about 10 min.....or get someone w/ a tech 2 to do it.

BULLETSSMOKE

battery disconnect got rid of the CEL but i know the codes are still probably there

CullinanCut

Just in case anybody else has this problem I just wanted to update what happened.

I haven't been driving the car a lot so this problem went on the back burner. I went back through the thread recently and took Sunburst SS's advice and had the thermostat replaced today and it seems to have fixed my problems. Went in with a check engine light and "---" on DIC and came out and I had a temp readout and no check engine light. The old thermostat didn't look so good either, the gasket was folded over and torn up looking. I guess time will tell if it is fixed or not but so far so good

Thanks to everybody that helped out in this thread

ThiZo_19

check the ect sensors resitance when engines cold, let it heat up see if it changes...

rollingboostedss

I just said F- it at this point I really am done messing with this motor I'll deal with it. the car is almost paid off then I can do the motor build I really want to do. sorry got off topic just venting

tehsscobalt

seems as if i am having the same problem. not the exact same, not even close really. Let me explain.

Every winter i get a "low coolant" warning. So i top off the coolant and go and everything is fine. Well, this winter comes around and i get the "low coolant" warning when i start my car. I turn it off, add coolant and leave thinking all is well. As im driving to work my CEL comes on...so im thinking its because of the low coolant and it will just clear its self, and it does. SOOO I'm driving home from work (not the same day, probably a month has gone buy at this point with no CEL) and my CEL comes on again. So im like WTF? the car is not running weird, still boostin really strong, still whining like a lil baby. I go to autozone and have the code checked, p0128. So i check coolant level and its fine, changed the temp sensor, cel still on. When im driving my temp never reads --- but it does only reach about 160, 170 and that's 22 miles of driving home from work.

I'm thinking the best thing for me to do right now is change the thermostat. my only question is HOW? was it hard to do? if you had it done at a garage, how much did it cost? I have very little car smarts, the most i have done is change injectors, change oil, add coolant. if anyone could give me some advise...it would be much appreciated.

Thanks!

Psytocrophic

i just posted something about this, its your thermostat sticking open.

bluelight

So at about 13000 (yes just 13000) miles one day I noticed my A/C wasnt working and I had the dreaded (---)for the temp along with the coolant fan full blast. I took it to the dealership and they couldnt replicate it. It started doing this off and on every couple thousand miles or so untill finally at about 37000 miles(Yes JUST out of warrenty) It started doing it non stop and this time had the engine light on! Luckily the dealership was cool about it and replaced the thermostat. This Fixed the problem and I even notice the temp reading is down from around normal op 190-235 to 180-190. But Now at 41000 miles its starting to give me the same issues! Is anyone else STILL having this problem after the thermostat was replaced. I mean WTF GM!

BULLETSSMOKE

Well my AC doesnt work about 99% of the time even after replacing my thermostat and the CEL going away

carshow2

http://www.blogcatalog.com/blog/rick...547027ca1d13ef

It supports the notion that the thermostat is the culprit. I've started having this problem - readout of "---" no A/C (and just when Minnesota decides to hit 95 in the middle of May :P). I took it to Autozone and had them read the error codes for me. Sure enough, P0128 popped up. I asked them (on the advice earlier in the thread) to clear the codes and, viola, I suddenly had temperature readings again and my A/C worked. So, I haven't replaced the thermostat yet, but it seems pretty promising.

BlkSS4dr

mine did that and they just replaced the t-stat and that was it

JWhit197

REVIVE THREAD

Okay guys this POS 2007 LT is pissing me off with countless recalls and problems and now this same freaking issue. I've had this particular issue for over a year now, on top of many others. I DID replace the thermostat (that was the first thing) and it came back on, same issue. Replaced coolant temp sensor, came back on. AC worked sporadically. Changed AC pressure switch on compressor, AC works, still have P0128. SO.... Please tell me what the hell to do now I've had nothing but problems with this car and I'm so ready to get rid of it.

To summarize, replaced thermostat, temp sensor, AC pressure switch within 1.5 years, same constant issue with P0128, but AC works now. The general consensus still seems to be a thermostat, of which I have a brand new one. Is there a good chance I bought a faulty thermostat the first time or should I not even waste my time installing another one?


...... Should have bought an import...

umrdyldo

iTrader: (1)

Not that it really matters but is it a factory thermostat?

Same temp and everything.

JWhit197

No it was the most expensive one OReillys had though, ha. I haven't had any issues with their quality in the past I doubt a thermostat would differ much from factory to aftermarket.

Sunburst_SS

Get an oem ac delco thermostat

umrdyldo

iTrader: (1)

Let me be blunt, I design new O'Reilly Auto Parts stores, they are great for some things. Engine parts and sensors is not one of them.

Even the lifetime warranty stuff is not so good. Engine stuff, stick with OEM.

ItalianJoe1

iTrader: (10)

This issue is NOT a thermostat, it's an electrical fault in the ECT circuit. It sees the circuit open or closed and that's what sets the p0128, there's a different code for tempertature below t-stat regulating temp and it won't cause the --- display or the lack of A/C function.

In most cases it's a faulty ECT sensor, I have also seen very rarely (including on my personal LSJ car) the wiring harness get rubbed through, and when it shorts out it sets that code, spikes the temperature to the point of seeing --- on the display and disables the A/C.

So if you tried a new Delco ECT sensor and it's not better, you need to trace the harness back and look for a fault in the wiring.

Sunburst_SS

P0128 is thermostat below regulating temp. I have seen it dozens of times on ecotec motors.....a lot of times the rubber seal in the thermostat gets rolled and doesn't allow the thermostat to work properly. And when the p0128 sets, in certain vehicles the coolant temp display in the cluster will show dashes and a/c will be disabled.

Snail_SS

iTrader: (3)

What sunburst said ive seen it happen first hand ^^

I went thru like 2 stats in 3 years (autozone)

ItalianJoe1

iTrader: (10)

My mistake, I thought the p0128 code was the circuit code.

I have replaced a bunch of ecotec T-stats as well, but I've also done a fair share of coolant temp sensor/wiring repairs. All comes down to proper diag.

If you are seeing a low temp that's usually a t-stat, but if it's -40 or something crazy, it's not the t-stat itself but usually a sensor/wire issue.

IIRC my car never even set a code because it was intermittent enough, but I would get the warning beeps and then the dashed display with the wiring fault issue.

Bob_LT

Sunburst_ss or someone, I hope you can help me. I was having the same symptoms most have posted in this thread. Sometimes I get the P0128 code. Coolant reads '---'. Whenever I get '---', I always lose my a/c. However, I don't always get a code thrown. And it's an intermittent problem. This had been going on for about a year and I replaced the t-stat with an A/C Delco oem from Amazon. Everything started working normal. Then I had the coolant flushed. All was fine for about a month, now the problem has come back 2 times in about 6 weeks. 2nd time was today. It usually self corrects, but I'm getting tired of the recurring problem.
What should I do next?
Thanks

YelloEye

iTrader: (3)

Have you tried the steps in post 7?
https://www.cobaltss.net/forums/prob...2/#post4283581

It's usually either a coolant temperature sensor or wiring.