Bruce Nunnally

Mailbag: A/C on causes Overheating

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2 hours ago, BodybyFisher said:

Ok, you need to check to see that the air purge line is clear, if it is clogged air can't get out of the cooling system.  This especially become a.problem on a cooling system refill. 

There is a hose that crosses from the coolant tank to the crossover.  It is located near the top of the tank, not the overflow hose, the other 3/8 hose.  When the engine is COOL.   Remove the clamp if there is one, and gently remove that hose and direct it into a coffee can, have a helper if you can start and idle the engine.  A stream of coola

2 hours ago, BodybyFisher said:

Ok, you need to check to see that the air purge line is clear, if it is clogged air can't get out of the cooling system.  This especially become a.problem on a cooling system refill. 

There is a hose that crosses from the coolant tank to the crossover.  It is located near the top of the tank, not the overflow hose, the other 3/8 hose.  When the engine is COOL.   Remove the clamp if there is one, and gently remove that hose and direct it into a coffee can, have a helper if you can start and idle the engine.  A stream of coolant should flow from that hose into the coffee can.  If not, the air purge is clogged, let me know the outcome and if its clogged, I'll tell you how to clear it

nt should flow from that hose into the coffee can.  If not, the air purge is clogged, let me know the outcome and if its clogged, I'll tell you how to clear it

 Have checked it before i will again nd it still ran a lil hot it went up one i turned the AC off it dropped down in like 30sec i turned the AC right back on nd stayed down till i turned back in driveway but i will try that once it cools off 

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1 hour ago, Chris Deville said:

I tooked it off nd let it run and water ran out that line it stop nd started back up a couple times was not comin out hard or fast but it did come out that line 

That is good then.  It will appear to spit and spurt, that is normal.

Please send a photo of your gage when you think it's hot.  Also post a video of the fans on high.

Your coolant level should be about 2 inches below the top of the tank.

Your coolant concentration MUST be at least 50/50, check it with a gage you buy.  Otherwise you will boil at a lower temp.  

Does coolant ever come out the overflow?

Is the front of the radiator clear of leaves, dirt and obstructions?

OEM thermostat?, or aftermarket?

You do realize that the waterpump has it's own belt correct?  Is that belt cracked, look shiny like its slipping?


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Ouch, now that will drive your blood pressure up. 

You have presented us with a problem that is not very common unless there is a catastrophic loss of coolant

So tell me again, this ONLY happens when the AC is on, otherwise it never does this?

Did you look at the fans when this happened?

Check codes right now, P codes and post them here.

Are they any other things that appear to be happening, coolant loss, boil over, coolant smell?

Ill do some research, lets see what others have to say.

Please answer my questions here, so we can fully understand what is going on.  


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I have not been following this post. 

Just a suggestion.. The coolant sensor may be bad.

That hot....it should be obvious the engine is that hot.....sizzles...bad smells....deep boiling sounds etc. 

I had a non GM product recently.....it was getting the 'stop engine hot warning' message etc. Coolant sensor was showing 285F+ or something like that on the scanner. 

Yet.... out under the hood...all seemed well. No massive heat wave blast...no boiling....no sizzle....no smells. 

The coolant sensor had shifted high. A new coolant sensor and all is well. 

 

Another idea.....maybe someone put in one of those high performance 'chip' resistors being sold on eBay a few years back.

Or....radiator may be clogged with sealer...."if a little bit is good..more must be better"..

Or...maybe a cooling fan wired backward...

 

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3 hours ago, BodybyFisher said:

Ouch, now that will drive your blood pressure up. 

You have presented us with a problem that is not very common unless there is a catastrophic loss of coolant

So tell me again, this ONLY happens when the AC is on, otherwise it never does this?

Did you look at the fans when this happened?

Check codes right now, P codes and post them here.

Are they any other things that appear to be happening, coolant loss, boil over, coolant smell?

Ill do some research, lets see what others have to say.

Please answer my questions here, so we can fully understand what is going on.  

Just seeing this and yes i can drive it all day wit the AC off. I can even let it run in one spit all day wit ac on just while im driving it goes up while the AC is on it will go down if i turn it off but for some reason it ant want to go back down at that time 

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1 hour ago, Logan said:

I have not been following this post. 

Just a suggestion.. The coolant sensor may be bad.

That hot....it should be obvious the engine is that hot.....sizzles...bad smells....deep boiling sounds etc. 

I had a non GM product recently.....it was getting the 'stop engine hot warning' message etc. Coolant sensor was showing 285F+ or something like that on the scanner. 

Yet.... out under the hood...all seemed well. No massive heat wave blast...no boiling....no sizzle....no smells. 

The coolant sensor had shifted high. A new coolant sensor and all is well. 

 

Another idea.....maybe someone put in one of those high performance 'chips' being sold on eBay a few years back.

Or....radiator may be clogged with sealer...."if a little bit is good..more must be better"..

 

@Logan, Bingo, that is EXACTLY with I was thinking above, asking for P codes, whether it was boiling over, etc.  This could be a false message.  Great minds, think alike :yupi3ti:


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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46 minutes ago, Chris Deville said:

Just seeing this and yes i can drive it all day wit the AC off. I can even let it run in one spit all day wit ac on just while im driving it goes up while the AC is on it will go down if i turn it off but for some reason it ant want to go back down at that time 

Do me a favor and check for codes as I asked above and report back P codes, thx


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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18 hours ago, BodybyFisher said:

@Logan, Bingo, that is EXACTLY with I was thinking above, asking for P codes, whether it was boiling over, etc.  This could be a false message.  Great minds, think alike :yupi3ti:

 

18 hours ago, BodybyFisher said:

Do me a favor and check for codes as I asked above and report back P codes, thx

My bad got off late

Abs-c1214 current c1248current 

Amp no code 

DDM- B3832current u1000history 

DDS no code 

DIM- p1536 history u1000history

IPC-u1000history

IPM-B0409current B0419current B0429current

IRC-u1000history u1164history u1016history

LRD no code 

PCM-p0118history p0410current p1115history 

PDM u1000history

RFA no code

RCC no code

RIM-u1000current 

RDd u100history

Sdm no code 

Vtd no code

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Here is your problem, @Logan nailed it.  Check the connection at the ECT sensor it is located on the rear head below the crossover facing outboard.  Because it is history, it may be intermittent.

P0118

P0118 CADILLAC - Engine Coolant Temperature Circuit High Input Repair Importance Level: 3/3 Repair Difficulty Level: 2/3  Possible causes Low engine coolant level Faulty Engine Coolant Temperature (ECT) sensor Faulty engine coolant thermostat Engine Coolant Temperature (ECT) sensor harness is open or shorted Engine Coolant Temperature (ECT) sensor electrical circuit poor connection

 


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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3 hours ago, BodybyFisher said:

Here is your problem, @Logan nailed it.  Check the connection at the ECT sensor it is located on the rear head below the crossover facing outboard.  Because it is history, it may be intermittent.

P0118

P0118 CADILLAC - Engine Coolant Temperature Circuit High Input Repair Importance Level: 3/3 Repair Difficulty Level: 2/3  Possible causes Low engine coolant level Faulty Engine Coolant Temperature (ECT) sensor Faulty engine coolant thermostat Engine Coolant Temperature (ECT) sensor harness is open or shorted Engine Coolant Temperature (ECT) sensor electrical circuit poor connection

 

I changed it nd still ran hot 

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You need to clear codes then and see if P0118 comes back in history again.  It could be in the connector or wiring.  Disconnect the battery fir 5 min, reconnect and drive the car for a day, then post codes here again.


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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So it is saying it is hot but it is not.

The only reason I can think of that it has in common with the AC is that there is more load which means more resistance in the cirvuits, and therefore a weak point will fail


GM FAN FOREVER

Nice, clean, luxury= fine automobile

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This appears to be an intermittent code because it is history. 

Why was this sensor replaced?   Did you test the old sensor with an ohm meter for accuracy and proper calibration with an ohm meter?  The resistance and temp parameters are in the FSM.

What was the connector like when you replaced it?  Did the connector feel loose when it was removed and replaced? Is there corrosion on the connector contacts?

The description of this code:

The DTC detects a CONTINUOUS open or short to HIGH in the ECT signal circuit or the ECT sensor.

I suspect that the message "ENGINE HOT - AC OFF" is in fact because the AC is ON.... and that you are actually getting similar conditions with the AC OFF, but because the AC is OFF, you don't get this message.  You seem to be getting a FALSE message.

I have a feeling that your TEMP gauge is inaccurate and probably HIGH.   Do not ignore this code, get this fixed, you will NEVER know if in fact you are overheating.

Check the connector at the ECT sensor for corrosion, looseness and that it is properly connected.  Check the wiring all the way up as far as you can go for burns and breaks

Also, show us a photo of the gauge with the AC off. Notice if you see the gauge on HOT or jumping up to HOT while you drive.

Let us know what you can find.


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I thinking its then fans dont think both run on high when its time and one dont blow that hard when its on low i replaced all 5 fues for fan still same gone buy new fans for it probably tomorrow and see way that goes and i replaced the temp sensor to see if it would still over heat and it did i also checked nd replaced both wires and the water has pushed has pushed back out of the resevere tank also think i need a new top for it it want hold no water or pressure at all but i will get back to u once i get the new fans nd top just ant had time have to get these other cars done 

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Suddenly you say it "pushed out of the reserve tank" and "you think you need a top (cap?) as it won't hold pressure"?

You describe coolant as water, that concerns me.  Is it 50/50 coolant concentration or water? How did you confirm that it is 50/50 coolant to water?, did you use a gage?

You replaced 5 fuses?, for fans, are there 5 fuses?, or do you mean relays?, I know there are 3 relays.  Do you mean fuses or relays?  You test fuses with continuity test.  

You replaced the engine coolant temp sensor "to see if it would still overheat"?

Chris first off, this is a give and take of information.  For these facts to come out now is maddening for people here who dont just parts replace "just to see" but they diagnose the problem based on diagnostic codes, symptoms and experience.  HOWEVER, to be able to help you we need an accurate report on what is going on, what has been done and full answers to our questions.

You sir are parts replacing and this has been frustrating.  

Where are you located?, if you are from another country maybe this is caused by a language barrier or a lack of understanding as to how this works 

It doesnt dawn on you to pressure test the cooling system and replace the cap since it's not holding pressure BEFORE replacing fans?  You do know that water/coolant boils at a lower temp with no pressure as compared to water/coolant under 16 psi of pressure correct?  Fix the loss of pressure FIRST.  A lack of pressure will allow the coolant to boil, if the cap doesnt hold pressure the coolant will leave via the overflow, causing more boiling.  

Playing this game, you will damage this engine

Until now we knew very little about what has been done and why.  Now I believe the history code for the ECT sensor was triggered by you and we were directed down the wrong path.

Good luck to you.  If I were you I would find a mechanic, that is not to be taken as an insult, these engines require specific experience and a basic understanding as to how cooling systems work, not parts replacing to diagnose them.  Understand this, replacing an engine coolant temp sensor or fans, relays, "just to see" when it has NOT set a code is not productive, especially when you say the system isn't holding pressure and the 'top' (cap) is questionable.

Did you disconnect the battery as I requested to see if the ECT sensor comes back?

If you want to DETAIL exactly what you have done from the beginning, what and how you tested, what you replaced AND WHY, maybe we can help, but in order to do so, we need to be on board 100%. 


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Keep in mind that at highway speeds the fans are completely unnecessary due to the air being rammed through the radiator.  If it overheats at highway speeds it is NOT the fans


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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U told me to check the temp sensor and the wires right and i didd the tem sensor had alot of corrosion on it so did the negative wire the temp sensor also looked to be burned it was turning colors u said it could be a false code u also said that the temp sensor code came up and they are 3 relays nd 2 30 fuses for the fans and with the coolant i had got the little tester u tild me to go buy with the little five balls in it but back to the fans i went nd got more relays for it because it onky seems as if inly one of them turn on high but it still runs the same  but maybe the way i bypassed the heater core creating this air pocket so maybe i am the reason but i have not done no more to it then was said or told to try in here 

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There is something VERY wrong with the communication here. 

YOU ORIGINALLY CHANGED THE TEMP SENSOR, and you still had the history code, I am trying to RUN down the HISTORY CODE.

You do NOT change a TEMP SENSOR without a code indicating a problem

You do NOT change relays without codes indicating a problem.

I said I thought you MIGHT have an intermittent code, to check the connector YES, but I also said to disconnect the battery to see if the code comes back

Did you disconnect the battery, to get rid of all codes and did the ECT code come back?  Disconnect the battery, drive a day, check codes, report them here.   

During the ride, take a photo of the TEMP GAGE, I want to see where it is

At the time I DID NOT know that your cooling system WAS NOT holding pressure, and the CAP or TOP as you say was suspect.  

YOU should NOT change the cooling fans if the system is not holding pressure and the CAP might be bad, that MUST be fixed first, or coolant will boil at a low temp and spiral out of control.

The coolant concentration must be at LEAST 50/50

If you removed the 2 hoses off the heater core and simply connect the hoses together that should be ok.  Explain how you bypassed the heater core?

FIX the pressure leak in the cooling system and replace the cap it MUST HOLD PRESSURE.   The upper hose MUST get hard. 

Do me a favor, write in bullet points, small paragraphs NOT large paragraphs, its too hard to slice and dice


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I am a little confused here.

If the pigtail had corrosion did you replace it?

IS there corrosion now at or in pigtail to the coolant temp sensor?

Are you thinking the engine is actually overheating or is it just saying it is? If it is actually overheating it should be pretty well hotter than normal under the hood.

Ditto on replacing the fans unless they were tested and failed. 


GM FAN FOREVER

Nice, clean, luxury= fine automobile

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19 minutes ago, rockfangd said:

I am a little confused here.

If the pigtail had corrosion did you replace it?

IS there corrosion now at or in pigtail to the coolant temp sensor?

Are you thinking the engine is actually overheating or is it just saying it is? If it is actually overheating it should be pretty well hotter than normal under the hood.

Ditto on replacing the fans unless they were tested and failed. 

Thanks rockfangd for commenting this has been confusing.  I do believe he stated it has boiled over, look at this post from above:

I thinking its then fans dont think both run on high when its time and one dont blow that hard when its on low i replaced all 5 fues for fan still same gone buy new fans for it probably tomorrow and see way that goes and i replaced the temp sensor to see if it would still over heat and it did i also checked nd replaced both wires and the water has pushed has pushed back out of the resevere tank also think i need a new top for it it want hold no water or pressure at all but i will get back to u once i get the new fans nd top just ant had time have to get these other cars done  

It wont hold water or pressure at all?


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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On 8/18/2018 at 4:43 PM, BodybyFisher said:

Here is your problem, @Logan nailed it.  Check the connection at the ECT sensor it is located on the rear head below the crossover facing outboard.  Because it is history, it may be intermittent.

P0118

P0118 CADILLAC - Engine Coolant Temperature Circuit High Input Repair Importance Level: 3/3 Repair Difficulty Level: 2/3  Possible causes Low engine coolant level Faulty Engine Coolant Temperature (ECT) sensor Faulty engine coolant thermostat Engine Coolant Temperature (ECT) sensor harness is open or shorted Engine Coolant Temperature (ECT) sensor electrical circuit poor connection

 

 

On 8/18/2018 at 9:10 PM, BodybyFisher said:

You need to clear codes then and see if P0118 comes back in history again.  It could be in the connector or wiring.  Disconnect the battery fir 5 min, reconnect and drive the car for a day, then post codes here again.

 

On 8/18/2018 at 10:28 PM, rockfangd said:

So it is saying it is hot but it is not.

The only reason I can think of that it has in common with the AC is that there is more load which means more resistance in the cirvuits, and therefore a weak point will fail

 

On 8/23/2018 at 10:57 PM, BodybyFisher said:

Thanks rockfangd for commenting this has been confusing.  I do believe he stated it has boiled over, look at this post from above:

I thinking its then fans dont think both run on high when its time and one dont blow that hard when its on low i replaced all 5 fues for fan still same gone buy new fans for it probably tomorrow and see way that goes and i replaced the temp sensor to see if it would still over heat and it did i also checked nd replaced both wires and the water has pushed has pushed back out of the resevere tank also think i need a new top for it it want hold no water or pressure at all but i will get back to u once i get the new fans nd top just ant had time have to get these other cars done  

It wont hold water or pressure at all?

The top was bad it is holding it ince i replaced it and  the bypass i did not have a 90degree spliter had to run the lines up a little to the one i did have but it runs wit the air on it just goes up 1 or 2 lines nd drops back down and im still yet haven't tested the fans but i am goin to tomorrow to see whats goin on there but i can drive it with the AC on now it just go up and come back down every now and then  

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Glad to hear you are making progress!


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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It just needed the pellets or some sealent in it and now no over heating i did not know that the northstar needed these pellets once u remove all the water or fluse the engine and it say it under the hood dont know why i kept over looking it had them just never thought to use them but i just dropped 2 in and like not even half a bottle of some block seal in it no more problems for now and it had passed all the test when we did them but thanks i really appreciate the help your time and help thanks again and i might be back got 4 more that i got to fix lol

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