Temp gauge and A/C problem

[Fasosa5]

Hi everyone, new member here.
my wife and I have had our 2010 4.6 for about 4 or 5 years now. Today as she was picked our daughter up from school she said the A/C was blowing hot air and the temp gauge hadn't budged from its resting place. When she got home I found that the upper radiator hose had been leaking (there was no longer any coolant in the reservoir) and the smell of coolant was very strong. I filled it with water to see if I could replicate the leak but nothing happened. The temp gauge also stayed down the whole time. Any insight would be greatly appreciated.

 

[Mark_888]

When you say "temp gauge hadn't budged from its resting place" what place is that? Is that at the bottom, top, or in the middle? If it is all the way down, your thermostat is broken. You must get this fixed immediately to prevent engine overheating, because the engine cooling system will not work properly if the system thinks the engine is cool, even though it is actually hot.

You need to have at least 40 percent coolant mixed with distilled water in the cooling system to keep the engine at proper temperature and keep it from over-heating. The temp should be below the half-way spot on the temp gauge.

 

[EdP]

Not sure if you car is set up that way, but with some, if the engine coolant is allowing overheating the AC will not go on so it does not add to the load of the radiator. Now that you added water, the AC may be working again. You may not see the leak until it heats enough to build pressure in the system. This is a good time to replace the hose and fresh coolant. Agree with Mark _888 about the T-stat if the temperature is not coming up. Replace it. If the bttom hose is old, get that too rather than have to blow out in August.

 

[Fasosa5]

I will definitely keep that in mind although I could feel hot coolant/water moving through both lower and upper radiator hoses. During my search for information though I found another thread with someone experiencing the same problem. Whenever their A/C starts blowing hot air their coolant temp drops all the way down (same as mine). I'm thinking the two may be somehow related.

 

[homeofstone]

OP. You said you have had car 4 or 5 years. Has the coolant system been checked and flushed during that time? It should have been.

 

[Fasosa5]

OP. You said you have had car 4 or 5 years. Has the coolant system been checked and flushed during that time? It should have been.

Yes

 

[OUsig]

My 2013rspec did the exact thing but only 1 time...! I noticed the AC wasn't cold whwn parked, looked at the engine temp and it was low. I turned off the car for a while and then drove off. The gauge went back to normal temp and AC worked fine.
Well just today I noticed the AC is warm again when at idle but the engine temp is normal (right below half).
I pulled over and popped the hood. I could hear the AC compressor kick on and the engine fan was barely moving

Seems I will be replacing that very soon

 

[Fasosa5]

[Update]
I removed the thermostat housing assy and found that the thermostat is open, I poured water in one side and it came out threw the thermostat. I also plugged my OBDII scanner in and got P0116 engine coolant temp circuit. I will be replacing the sensor as soon as it comes in this evening.

 

[OUsig]

great please be sure to follow up as I just ordered a new fan assembly...will update when I replace that also

 

[Fasosa5]

[Update]
New sensor installed but no change occurred. I am now waiting on a new thermostat. It will take a few days to get here but I will update once it's installed.

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[OUsig]

Just to add
I ordered new radiator hoses, engine belt and the full fan assembly.
My car is doing the same as the OP. Today is very humid here in the Dallas area. AC doesnt do anything unless driving and now my engine coolent is reading at min/low all day.

I have left the AC off and prop the hood up when I stop as I am paranoid about it overheating.

Will keep this thread updated with my issues and hopefully fixes!

 

[Fasosa5]

[Update]
O.P. Here, new thermostat arrived today. I changed it out but am having no luck. As of today the car now has a new coolant temp sensor and thermostat but the problem remains. I will be taking to a shop tomorrow as I now suspect the problem my lie within the A/C system itself. My suspicions come from other members who have posted similar symptoms and mentioned replacing the compressor. Unfortunately they did not update their post so I don't know if that will solve the issue.

 

[OUsig]

Does your AC blow cold air when you are driving? If so the AC isn't the issue.
There are many sensors working under the engine bay for the engine cooling and AC/temp system.
I'm sorry if stated already but have you looked at the radiator fan to make sure it was engaging appropriately?
I am going into the dealership this Thursday for a full diagnostic and will report back.

 

[Fasosa5]

Does your AC blow cold air when you are driving? If so the AC isn't the issue.
There are many sensors working under the engine bay for the engine cooling and AC/temp system.
I'm sorry if stated already but have you looked at the radiator fan to make sure it was engaging appropriately?
I am going into the dealership this Thursday for a full diagnostic and will report back.

No, the A/C blows hot air all the time. Radiator fan also functions as it should.

 

[OUsig]

Any update OP?
My update is I replaced the engine fan, belt, hoses and coolent flush.
Engine fan still doesn't turn on 🤣 good times.
So I gave in, at the dealership now to get it figured out.

 

[OUsig]

Ok got my car back. It is the fan controller. Apparently an important part with a list price of $460. Part # 25385-3M280

 

[Fasosa5]

[Update]
O.P. here, this will be my final update as the problem seems to have been solved. I ended up taking the car to a trusted mechanic. The connected their scanner and found additional codes that my handheld scanner didn't. The important code being oil temperature sensor. At some point (cause still unknown) the oil temp read too high and caused the car to go into limp mode. This cause the a/c to blow hot air and the thermostat to stay open with the radiator fan on keeping the cooling as cold as possible. They simply reset the trouble codes and completed a drive cycle and had the car functioning as normal. It has been a week since and so far no issues.

 

[OUsig]

NICE! better outcome than myself but good to hear

 

[OUsig]

Final update here. turns out it was the fan control module. Expensive part new yet I found one online from a wrecked Genesis for $80.
Dealership wanted 2 hours labor to instal. I did it in 30 minutes...no problem if this happens to anyone else.
Now my fan works as it should! Never thought that would be so exciting

 

[OlderGuy1stGenesis]

[Update]
O.P. here, this will be my final update as the problem seems to have been solved. I ended up taking the car to a trusted mechanic. The connected their scanner and found additional codes that my handheld scanner didn't. The important code being oil temperature sensor. At some point (cause still unknown) the oil temp read too high and caused the car to go into limp mode. This cause the a/c to blow hot air and the thermostat to stay open with the radiator fan on keeping the cooling as cold as possible. They simply reset the trouble codes and completed a drive cycle and had the car functioning as normal. It has been a week since and so far no issues.

I would accept most but not all of your diagnosis. yes, a sensor can go bad and ''lie'' causing other problems through inaccurate sensing. I dealt with this for years in commercial, industrial air conditioning. Yes (based in information received, true or false, it might kill the enable command for the AC.

And yes a modern car could command one fan or multiples to remain on. But as far as I know all modern thermostats are wax pellet or mechanically operated. That is, they start out closed, and open only according to temperature, (wax formulation either opens at lower or higher temperatures), so that is fixed on engine operation time and ambient temperature. So we could command an electric fan on, yes, but command a wax pellet thermostat open ? not in your life !