2014 Sierra overheating

[Joe 121]

I've got a problem with my 2014 Sierra 5.3L.  I live in Florida where the temperatures are in the high 90s this time of year and the humidity reaches up into the 90s as well.

 

It began about a week ago when I noticed the AC wouldn't blow cold on occasion.  The gauges indicated the compressor was functioning properly and the temperature inside the cab (at the time I checked) was in the high 60s.  I left the thermometer in the vent and found there were times when I was driving that it was blowing air in the 80s.

 

I was on my way to Tampa on Friday (I75) and I was angry that the AC was blowing hot again.  The idiot gauge on the dash was hovering just above 210.  A message popped up stating that the ECM was going to shut off my AC because the engine was overheating.  The idiot gauge was now halfway between 210 and 260 (235?). 

 

I pushed the button to turn off the AC and I could see the needle drop back down to 210 almost immediately.  After a minute, I turned the AC back on (it was actually blowing cold air) and the gauge stayed at 210 (with the AC on).  The outside temperature (according to the dashboard) was 101.  The next time I pulled out to pass, the temperature gauge began to climb back up.  I switched off the AC again and the needle dropped back down without me taking my foot off the gas.  I made the 200 mile trip by cycling the AC off and on traveling between 65 and 70 MPH.  When I stopped at my destination, I could hear the radiator fans blowing on high.  After it cooled, I checked the radiator (overflow reservoir) was full.  Both Fans came on low speed after a minute when I started it back up. 

 

The trip home on Sunday was the same.  I made it by cycling the AC off and on.  It only seemed to have a problem when I accelerated to pass and dropped down when I turned off the AC. The outside temperature was in the low 90s.  I have made this trip many times in the past without problem under what I am certain are the same conditions.

 

There were no new trouble codes.  I had expected to see something related to the message threatening to shut off the AC.  But the only codes I found complained about a burned out bulb at the license plate and some low voltages in the radio/amplifier.  There is no noise (that I can hear) or any signs of a leak around the water pump.

 

The truck is 10 years old.  I put all 170K+ miles on it myself.  I have replaced the transmission and the AC condenser over the years.  The trans thermostat has been removed.  Around 120K, I flushed the radiator, replaced all the hoses, replaced the thermostat with the Cadillac one (194?) and installed a new temperature sensor.  Last oil change (maybe 1K miles ago), I started using that Valvoline 5W30 Restore and Protect.  The oil pressure gauge (for what it's worth) shows a solid 40 and the oil level is full.

 

I bought a new water pump and I am looking for a 180 thermostat and temp sending unit. 

 

I understand that by turning the AC off, I was significantly lowering the temperature entering the front of the radiator, but I am hoping someone can help me understand what was causing the AC output temp to climb in relation to the engine temp or is that not true?  Did the ECM shut down the compressor without turning off the light on the dash?  If the compressor was already off, why did my pressing the AC button (to turn it off) have an immediate affect on the temp gauge?  The AC was blowing hot air off and on at least a week before this trip.  It wasn't until I was on the highway that I found what appears to me to be some kind of relationship.

[Buckwild27]

1 hour ago, Joe 121 said:

I've got a problem with my 2014 Sierra 5.3L.  I live in Florida where the temperatures are in the high 90s this time of year and the humidity reaches up into the 90s as well.

 

It began about a week ago when I noticed the AC wouldn't blow cold on occasion.  The gauges indicated the compressor was functioning properly and the temperature inside the cab (at the time I checked) was in the high 60s.  I left the thermometer in the vent and found there were times when I was driving that it was blowing air in the 80s.

 

I was on my way to Tampa on Friday (I75) and I was angry that the AC was blowing hot again.  The idiot gauge on the dash was hovering just above 210.  A message popped up stating that the ECM was going to shut off my AC because the engine was overheating.  The idiot gauge was now halfway between 210 and 260 (235?). 

 

I pushed the button to turn off the AC and I could see the needle drop back down to 210 almost immediately.  After a minute, I turned the AC back on (it was actually blowing cold air) and the gauge stayed at 210 (with the AC on).  The outside temperature (according to the dashboard) was 101.  The next time I pulled out to pass, the temperature gauge began to climb back up.  I switched off the AC again and the needle dropped back down without me taking my foot off the gas.  I made the 200 mile trip by cycling the AC off and on traveling between 65 and 70 MPH.  When I stopped at my destination, I could hear the radiator fans blowing on high.  After it cooled, I checked the radiator (overflow reservoir) was full.  Both Fans came on low speed after a minute when I started it back up. 

 

The trip home on Sunday was the same.  I made it by cycling the AC off and on.  It only seemed to have a problem when I accelerated to pass and dropped down when I turned off the AC. The outside temperature was in the low 90s.  I have made this trip many times in the past without problem under what I am certain are the same conditions.

 

There were no new trouble codes.  I had expected to see something related to the message threatening to shut off the AC.  But the only codes I found complained about a burned out bulb at the license plate and some low voltages in the radio/amplifier.  There is no noise (that I can hear) or any signs of a leak around the water pump.

 

The truck is 10 years old.  I put all 170K+ miles on it myself.  I have replaced the transmission and the AC condenser over the years.  The trans thermostat has been removed.  Around 120K, I flushed the radiator, replaced all the hoses, replaced the thermostat with the Cadillac one (194?) and installed a new temperature sensor.  Last oil change (maybe 1K miles ago), I started using that Valvoline 5W30 Restore and Protect.  The oil pressure gauge (for what it's worth) shows a solid 40 and the oil level is full.

 

I bought a new water pump and I am looking for a 180 thermostat and temp sending unit. 

 

I understand that by turning the AC off, I was significantly lowering the temperature entering the front of the radiator, but I am hoping someone can help me understand what was causing the AC output temp to climb in relation to the engine temp or is that not true?  Did the ECM shut down the compressor without turning off the light on the dash?  If the compressor was already off, why did my pressing the AC button (to turn it off) have an immediate affect on the temp gauge?  The AC was blowing hot air off and on at least a week before this trip.  It wasn't until I was on the highway that I found what appears to me to be some kind of relationship.

You'll want to get a gm temp sensor not an off brand one. I personally switched thermostat housings to this one that uses a ls3 style thermostat. I don't use my A/C so I can't help with that issue. 

 

https://www.montmotorsports.com/dms-billet-thermostat-housing-w-ls3-style-160-degree-thermostat-gen-v-lt/

Edited July 29, 2024 by Homewrecker007

[Texasdeere]

If the cooling fans are running properly and the coolant looks good I would suspect the thermostat and or the temp sensor.

 

Most of them seem to fail open.  But anything is possible.

 

I have no idea what is going on the the AC though.  That's a weird one.

Edited July 29, 2024 by Texasdeere

[Joe 121]

@Homewrecker007160 thermostat seem kind of cold to me.  That website doesn't show any other options.  How do you get by in those Ohio winters?

[mikeyk101]

Last year, I had to replace my thermostat in my 2016 and put in a Motorad 194⁰ thermostat as I wanted a "cooler" thermostat than the stock 207⁰ one. My OEM was getting stuck open and middle of winter and I wasn't getting enough heat. I wanted the 194⁰ as I also tow a toy hauler occasionally and figure this would help with cooling in warmer weather. The Motorad one began to fail maybe 4 or 5 months later and it was sticking closed or partially closed causing hotter coolant temps. I was getting the higher temps like you when accelerating or running at extended highway speeds. I will never by another Motorad part again. IMHO, for these parts and several others on these trucks, OEM is the way to go. I ended up going back to a GM thermostat but discovered that the thermostat for Corvettes and Cadillac CTS was a 194⁰ and an exact swap. I installed that and it went back to normal. The part number for that is 15-11113 or 12674634

 

GM Genuine Parts 15-11113 Water Pump Outlet Assembly with Thermostat https://a.co/d/fKzyzNL

 

And just an fyi, the coolant temp gauge on the dash is pretty worthless. 210⁰ is the "normal" temp it shows but that doesn't mean the coolant is at 210⁰. It could be as low as 185⁰ or as high as 225⁰ and will still show 210⁰. If it is moving up, it's already heading to 230⁰ or higher. 

Edited July 29, 2024 by mikeyk101

[Buckwild27]

8 hours ago, Joe 121 said:

@Homewrecker007160 thermostat seem kind of cold to me.  That website doesn't show any other options.  How do you get by in those Ohio winters?

I got 187° thermostat. You can toss the 160° it's the only way you can get the housing to run the ls3 style thermostat.  

[Joe 121]

@Homewrecker007That makes much more sense.  Back in the old days, I lived in Ohio.  I had this great idea that I could run my 70 Barracuda without any thermostat at all.  I didn't make it past November.

 

@mikeyk101It's that Cadillac thermostat that I have installed right now.  I didn't understand until recently why the temp gauge continued to show 210 degrees.  50K miles later, I think that is what my problem is.  I had the truck out today with the scanner plugged in.  I could see the temperature changing as I drove.  I had to quit when I couldn't get the temp below 236 even with the AC off.

 

I think that is telling me the temp sensor is working, but it won't hurt to replace it anyway.

 

I saw this question asked before (I think it was Grumpy Bear), but I didn't see an answer.  Does anyone have a part number for the 180 thermostat in the housing?

  

[Buckwild27]

27 minutes ago, Joe 121 said:

@Homewrecker007That makes much more sense.  Back in the old days, I lived in Ohio.  I had this great idea that I could run my 70 Barracuda without any thermostat at all.  I didn't make it past November.

 

@mikeyk101It's that Cadillac thermostat that I have installed right now.  I didn't understand until recently why the temp gauge continued to show 210 degrees.  50K miles later, I think that is what my problem is.  I had the truck out today with the scanner plugged in.  I could see the temperature changing as I drove.  I had to quit when I couldn't get the temp below 236 even with the AC off.

 

I think that is telling me the temp sensor is working, but it won't hurt to replace it anyway.

 

I saw this question asked before (I think it was Grumpy Bear), but I didn't see an answer.  Does anyone have a part number for the 180 thermostat in the housing?

  

If I'm remembering correctly he has a remote thermostat housing with a ford thermostat in it. But I'm not 100% on that one. 

[mikeyk101]

There is obviously something not right with your coolant system. Since you have that 194⁰ thermostat in, it shouldn't be heating up like that. Makes me wonder if there may be a blockage in one of the passages or even a bunch of clogged fins in the condenser as well as the radiator blocking air flow.

 

The only time I have had issues (except with the motorad thermostat) and this was when I still had theboriginal stock 207⁰ thermostat was when pulling a toy hauler which was just over 6000lbs up a 7-8⁰ grade out west for several miles. And I was stupidly trying to run at 55-60mph to keep up with another couple I was traveling with. Coolant temp soared, oil temp soared, trans temp soared, all kinds of warnings began showing up on dash and told me I was close to limp mode but there wasn't anywhere to pull over and let it cool down until close to top. Other than that, and the bad motorad experience, no issues.

 

I even towed my toy hauler a couple weeks ago a couple hundred miles and was running 65mph for quite a few of those along with stop and go traffic and no issues. Temps were in the lower 90's. Never had to shut off the AC and it was nice and cool. (Knock on wood because I'm still fully expecting the condenser to spring a leak soon...). Granted, no serious grades but there were quite a few rolling hills.

[Joe 121]

@mikeyk101I checked the condenser for damage/blockage.  It looks good from the front.  To me, it's acting like a stuck thermostat or a broken water pump.  Now I don't if water pumps still loose their impellers anymore, but I have seen it in the past (distant past).  It's also possible for the thermostat (even if it's factory) to be stuck partially open.  I won't know until I open it up.  the Parts I've ordered should be here by this weekend.

 

What I don't understand is why my AC is intermittently blowing hot air.  I can't think of a reason these problems might be related, except that they appeared to have started about the same time.

 

While I have your attention, can somebody explain to me why I can buy 1lb cans of 134A, but I can't get a 20lb cylinder?  Those 1lb cans waste more freon than anything else.  Maybe I just don't know how to suck all the freon out of them.  I'm still using a scale and the compressor to charge a system.

[Buckwild27]

1 hour ago, Joe 121 said:

@mikeyk101I checked the condenser for damage/blockage.  It looks good from the front.  To me, it's acting like a stuck thermostat or a broken water pump.  Now I don't if water pumps still loose their impellers anymore, but I have seen it in the past (distant past).  It's also possible for the thermostat (even if it's factory) to be stuck partially open.  I won't know until I open it up.  the Parts I've ordered should be here by this weekend.

 

What I don't understand is why my AC is intermittently blowing hot air.  I can't think of a reason these problems might be related, except that they appeared to have started about the same time.

 

While I have your attention, can somebody explain to me why I can buy 1lb cans of 134A, but I can't get a 20lb cylinder?  Those 1lb cans waste more freon than anything else.  Maybe I just don't know how to suck all the freon out of them.  I'm still using a scale and the compressor to charge a system.

https://refrigerantscenter.com/products/r134a-30lb?variant=41525582233669&cmp_id=568504723&adg_id=1180877249544920&kwd=&device=m&utm_source=bing&utm_medium=cpc&utm_campaign=Shopping July 2024&utm_term=4577404353503663&utm_content=Ad group %231

[Joe 121]

@Homewrecker007Thanks, that was helpful

[Joe 121]

I replaced the water pump as planned.  The old one did not show any signs of failure that I could see, but it has 175K+ miles, so it's gone.  The old antifreeze looked good to me, nice and pink.  I installed the Mishimoto 180 thermostat and put it all back together. 

 

According to my scanner, with the AC on, it is running between 181 and 183 in the city (500 to 1.5K RPM).  If I hit the throttle (up to 3K RPM), it will climb to 190 and then go back down (about half a minute).  Maybe twice in a half of an hour, it did climb to 190 without going above 1.5K, but it didn't stay there vary long.  The A/C stayed in the middle 60s, but I wasn't driving very long (89 degrees with Humidity near 80%).

 

I have no experience with tracking the temperature at this level, so I have no idea what to expect.

 

I didn't have time to take it out on the highway today as my good friend Debbie is coming to visit tomorrow morning and I need to get the house ready for her.

[Joe 121]

Put it in tow mode and got out on the highway.  It mostly stayed between 181 and 183.  It did jump to 190 when I accelerated from 60 to 70 and got the RPM up to 4K for a few seconds.  It recovered quickly.  This was all with the A/C on.  I could push the RPMs up but I really don't know what to expect at this level of tracking the temp.  Anyone have any suggestions?

 

I've convinced myself it was the thermostat and the A/C was a red herring. Next is to figure out why I'm only getting down to mid 60s when others are reporting A/C in the 50s.

[CamGTP]

The rise in temps with an RPM increase like that is normal on a LS or LT engine, every single one I've owned has done that. I can make my truck see 220-225 easy on a 0-80mph down an on ramp or while I'm doing tuning. After 30 seconds to a minute the temps are back down to normal as all the coolant runs through the radiator. In the winter time it's much harder to see those temp swings as the outside air stays in the 0-25 degree range.

 

My uncles 2014's had  lack luster A/C too and needed the condenser replaced on it like they all do. After replacing both the compressor and condenser the A/C temps are right back down into the 40's even on muggy hot days here.