Could be the temp sensor. When it goes the AC won't work also, it's the truck trying to save itself.

 

Is the coolant reservoir cap on correctly? You need to get the codes, obviously.

 

OBD scanner gave a P0128 code, Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). I cleared the code and for some reason it worked after that. Will see if i get the same symptoms tomorrow and if the code comes back, will keep you posted.

 

Ahhh, ok, that means the t-stat is bad, stuck or sticking open. It won't heat to operating temp. This will kill the AC too.
Watch your temp carefully, I think you will find it won't heat up.

 

is your coolant reservoir full? if you suck in a gulp of air the temp sensor might go "dry" and exhibit this symptoms.

 

I have seen some thermostats at 203 degrees on the newer vehicles.

 

Yes, they have gotten hotter over the years, emissions .....
before computer controls 185 was the norm.
I still remember some older GMs like in the 90s would not even turn on the fan until 230 degs! Running the AC kept them cooler because the fan ran with it on. I always thought that was kind of crazy.

 

I remember 160/180 in the 70’s. 203 is just a little to close to boiling for my comfort.

 

Don't forget it won't boil under pressure. We are at maybe 14 psi. that's like 250 deg boiling I think.

 

Just wanted to follow up on my post. I have not encountered the symptoms since I cleared the code. I also seem to be operating at normal temps, I would guess the line is at the 195-200 degree mark.

And to clarify my topping off of the coolant comment, i probably put in about 8-10 oz, it was sitting about 1/2-3/4" below the line. Not sure if that helps determine the cause or not.

 

Just wanted to follow up on my post. I have not encountered the symptoms since I cleared the code. I also seem to be operating at normal temps, I would guess the line is at the 195-200 degree mark.

And to clarify my topping off of the coolant comment, i probably put in about 8-10 oz, it was sitting about 1/2-3/4" below the line. Not sure if that helps determine the cause or not.

Looks like you may have corrected it. Be on the lookout for the coolant level to go down. If you have to add anymore, pull the truck up on a slight incline, and add the coolant slowly while the engine is running and the heater on max. This will burp the air bubble if there is one. Will cause the gage to register accurately too. I have had good luck running mine slightly above to Full coolant line.

 

Oh that’s what causes that water rushing sound! Yes, I do get that, but not regularly so I just lived with it.

 

yes, VERY common, the fix is a little overfill. There is a new coolant bottle out for some trucks but I wouldn't bother.

 

well, i'll just go ahead and toot my own horn.

i called it in post 5

toot toot

 

[/QUOTE]


I’ll bough out!

 

 

This Hvac on my truck is the worst system I ever owned, sooo finicky, the AC especially if you park it outside in heat I will never get cold enough, but keep it inside garage and it's good ?????

 

Sounds like it's likely getting low on refrigerant.

 

On burping, I think I had been driving for a full year before my system got a proper pruge.
It happened after I had to floor it to avoid getting squished. next day I I look at the coolant reservoir to see it almost empty.
I don't have any leaks and have used the heater previously.
Takeaway is, it takes more than normal driving to fully purge all the air.

 

Wanted to weigh in here. This problem occurred last year same as described on my Canyon. It has something to do with the temp sensor. When it 1st happened to me I thought maybe the battery was going bad. After 4 years old in Florida, heat is a major factor in battery life. I removed the battery and had it tested. There was no issue but to my surprise everything came back up like it should after I reinstalled the battery. Probably due to a system reset from power failure. Cut to last week, and the issue occurred again. I have an extended warranty expiring in 8k miles so I took it straight to the dealer the next morning. They had my truck for 6 days. IT IS the temp sensor and thermostat. Not sure which was the actual problem but they replaced both under the extended warranty. Probably because they go hand in hand and it can be very difficult to remove the sensor without removing the thermostat housing. The sensor is located just next to it under the the intake manifold. The AC will not cool when the temp sensor goes as a safety feature so you don't overheat the engine. Since the computer can't determine the actual temperature of the vehicle, it triggers AC shutoff so the clutch doesn't run and over exert the engine if there is a cooling issue. The fan comes on for about 10 minutes and shuts off to allow for cooling since it can't tell WHAT temperature the vehicle is actually running at. As soon as the temp sensor was replaced, the AC came back on with no problems. The temp sensor is about 15 bucks. I recommend anyone experiencing this issue just replace that sensor. It fixed my issue. The thermostat is a little more expensive at around 75 dollars because it comes attached to the housing. So they are replaced together. It is not the cooling level that causes this. There is however a bulletin on some vehicle regarding the water rushing sound in the coolant system. As long as your levels are good, this rushing sound is nothing to be worried about. However, the bulletin on this simply recommends replacing the coolant reservoir to the newer design to resolve it. This resolved my issue and was performed by the dealer as a voluntary recall. https://static.nhtsa.gov/odi/tsbs/2019/MC-10165086-9999.pdf

This is the web address for the tech bulleting on a chevy malibu. But since they had the same coolant reservoir, they covered it for me. Your dealer may do the same. Couldn't hurt to ask.

 

You likely got a new temp sensor for no reason. (not a bad thing) 99 times out of 100 it's the t-stat sticking open.
It is true the PCM will shut off the AC but I doubt the engineers did it because of "over extending the engine". It is more likely so there will be no heat from the AC condenser when it's not sure of the temp. Another explanation is that it makes you get it fixed because you have no AC, lots of people could care less about the CEL (check engine light). Funny, I remember Fords in the late 80s and early 90s that had no CEL would idle bad if there was a problem (and code set). It didn't matter if the problem had anything to do with the idle or not. I never went to Ford training but I do remember a guy I worked with told me this and why it idled bad. It's so you would take it in and get it fixed.

 

The new vehicles now have an electronic temperature sensor in the negative cable that detects any heat from an arc, it can trip and shut off communication to the ECM and can even set codes which can shut down the charging rate output of the alternator. This can happen when hooking up jumper cables to the negative post instead of the preferred good metal ground. It can also shut down alternator output if a bad battery is detected by the ECM.

 

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So.. I had the same situation as described here.. But since i had my code scanner with me.. I have a bit more info.

Temp gauge was pegged low. When I noticed this, I pulled over and dug in the backseat for my scan tool and plugged it in.. Showed a pending code of P0128

However.. the coolant temp sensor PID was reading 170 degrees.

Shut the vehicle off and toggled the key to verify the 'sweeps' of the gauges to verify that the temp gauge wasn't bad.. That all worked fine.

The COOLANT temp sensor seems to hang around the 170 degree range. I started up this morning, all worked fine and the pending code has gone away.. Kept the tool plugged in and the Coolant temp sensor hung around the 170 degree range, but the temp gauge was at its normal of approximately 205 degrees.

So, data feeding that gauge seems to be coming from something OTHER than the coolant temp sensor (Which seems to be a real PITA to get to on the V6)

I've got an appointment for the dealer to check it on Thursday. I didn't have any "No A/C" messages or the like, but the cooling fans were running when I shut the vehicle off. Which, I believe, as others have mentioned here is part of the strategy from a safety standpoint.

But, the fact that the Coolant PID showed 170 while the temp gauge showed 205.. And showed 170 when the temp gauge showed pegged low (160 is lowest reading).. I think there's something else at play here. May still be a sticking thermostat for me, may be for others.. But.. Just feels like there's something else happening. I can't find anything else showing as an engine temp or anything else that would be driving the gauge.

 

I have this same issue, the temp gauge will read pegged low to 160 degrees, A/C compressor will not turn on and the fan runs on high for a few minutes after the vehicle is shut off. If I cycle the key the coolant temp gauge sweeps normally but the returns to pegged low at 160 degrees even though the truck has been running and is warm. When I pull codes the truck has the same P0128 code, Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). If I perform a 30 second 12 volt reset on the truck then switch the key to or start the engine the coolant temp gauge reads normally. The 12 volt reset seems to work for about a week in the cooler months and multiple weeks in the warmer months. I have done this multiple times and it works every time. I makes me wonder if there is a software bug or splayed terminal issue. I don't see how a 12 volt reset would unstick a thermostat.

 

very interesting!
Do we have an electric thermostat. I know they are out there.
I don't think we do on the v6. But the I4? Do you have the 4 cyl ?

 

I’ve probably reset it 20 times. Works every time instantly. I really doubt it’s the thermostat.

 

gotcha, strange one
I think I would confirm the coolant temp with a infrared thermometer and go from there. Sounds like from your description it is hot, but reads cold, then you clear the code and it reads hot like it should...?
weird

 

I have the same issue my AC stopped working found the compressor clutch not engaging and now my temp cluster has dropped to low and the fans continue to run after I shut it down , I bought a new compressor but not installed yet did we ever decide that it was the Temp sensor thats gone Tango uniform?

 

The thermostat is the issue 95+% of the time, the disabled A/C and cooling fan staying on are a failsafe triggered by a P0128 DTC, and coolant temp sitting at 160F goes along with it as a result of the t-stat sticking open.

 

Alright now I’m playing this game literally happened overnight. I have changed the temp sensor and the thermostat. Still not indication on the temp gage engine light comes on after about the 3rd start up. AC is not blowing cold, after shutdown fan runs on high cycle for a couple of minutes. Now when I use the scan tool to reset the codes I’ll get low fuel caution but it’s full, service stabilitrac, roll down the up driver window. What is going on…!?

 

My 2020 Chevy Colorado is doing the same thing I replaced the sensor the thermostat and the battery and it’s still doing the same thing. I’ve reset the codes, the check engine light comes back on temperature gauge stays at zero or 160 because that’s as low as it goes the AC blows hot and the check engine light is on. I can’t figure it out.

 

Most likely you got a Bad Thermostat again
But, if when you were replacing the Temperature Sensor the connector got damaged that would also cause the same issue.

One way to confirm is to use a Diagnostic Tool (Not Code Reader) and see what Temperature the Engine is actually saying it is.
If it is warming up and showing an increasing temperature.. Then it tells you the thermostat is bad.
If it is not giving you a temperature that makes sense... They it is the temperature sensor