Air conditioning not working when cooler outside.

[RangerBill]

Just some added random information. I don't see why this would be connected but I try not to ignore things coincidences. My engine is wanting to idle high and I also can smell a hint of diesel exhaust as well. It may very well have nothing to do with the AC issue, and it may have had something to do with driving in flooding conditions, I'm not sure. It just seems odd.

Check for any DTC codes.

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[Motorpsychology]

Interesting........ This is a first as I have seen others including my 2012 Frontier operate the Compressor in freezing temps. I'm pretty sure my 2022 Transit does the same.

The A/C button may light, but does the compressor clutch actually engage below 32ºF/0ºC? I'm guessing most modern systems have either a thermal or load shutdown to disengage or prevent engaging the compressor as the refrigerant oil thickens with colder temps, and possibly damaging the compressor or bursting a high pressure line.

 

[Frenchy]

The A/C button may light, but does the compressor clutch actually engage below 32ºF/0ºC? I'm guessing most modern systems have either a thermal or load shutdown to disengage or prevent engaging the compressor as the refrigerant oil thickens with colder temps, and possibly damaging the compressor or bursting a high pressure line.

In my 2012 I don't have to have the AC Compressor commanded by me to have it turn on necessarily. As long as the defrost or defrost/floor is selected then it will engage it.

 

[Grandaccess]

Right, the AC compressor just will not engage unless it's hot outside. It was like 78°F when this was going on. Definitely didn't want to use my heater . Maybe I just need a charge? But I didn't know if there was a different solution before going that route.

78F?
After the truck itself comes up to Temp does it work?

it could be Much worse! I am already at the high for today LOL

 

[Grandaccess]

The A/C button may light, but does the compressor clutch actually engage below 32ºF/0ºC? I'm guessing most modern systems have either a thermal or load shutdown to disengage or prevent engaging the compressor as the refrigerant oil thickens with colder temps, and possibly damaging the compressor or bursting a high pressure line.

The A/C button may light, but does the compressor clutch actually engage below 32ºF/0ºC? I'm guessing most modern systems have either a thermal or load shutdown to disengage or prevent engaging the compressor as the refrigerant oil thickens with colder temps, and possibly damaging the compressor or bursting a high pressure line.

I just seen his location, South America, for them its a Bad Time for the AC to stop working
you would find me slumped over the wheel in walfart parking lot if my AC didnt come on right away, I would call a tow truck, I stop Breathing at 72F

 

[skrumpe]

The A/C button may light, but does the compressor clutch actually engage below 32ºF/0ºC? I'm guessing most modern systems have either a thermal or load shutdown to disengage or prevent engaging the compressor as the refrigerant oil thickens with colder temps, and possibly damaging the compressor or bursting a high pressure line.

It's actually a pressure switch that relies on pressure of the refrigerant to engage the clutch, at least it was when I was certified in automotive AC. I had a 1984 LTD wagon I converted to 134a about 25 years ago and had to bypass the switch to start filling it. On this one, it was on the accumulator/drier, other cars had it on the low pressure line. It's to keep from running the compressor without refrigerant to keep from burning it out, but also likely to your point about the oil circulating in the system.

As to the point about the clutch not operating in sub-freezing temperatures, it's because the pressure tends to drop so low that the switch doesn't engage. As for Frenchy's point, it's possible the engine compartment warmed everything up enough to raise the pressure to the point the compressor engaged.

 

[Grandaccess]

It's actually a pressure switch that relies on pressure of the refrigerant to engage the clutch, at least it was when I was certified in automotive AC. I had a 1984 LTD wagon I converted to 134a about 25 years ago and had to bypass the switch to start filling it. On this one, it was on the accumulator/drier, other cars had it on the low pressure line. It's to keep from running the compressor without refrigerant to keep from burning it out, but also likely to your point about the oil circulating in the system.

As to the point about the clutch not operating in sub-freezing temperatures, it's because the pressure tends to drop so low that the switch doesn't engage. As for Frenchy's point, it's possible the engine compartment warmed everything up enough to raise the pressure to the point the compressor engaged.

The OP is Not in North America.
78F is not sub-zero

 

[smittybr]

78F?
After the truck itself comes up to Temp does it work?

it could be Much worse! I am already at the high for today LOL

Yes, in the mid to upper 70s Fahrenheit, it doesn't want to engage. But man... This humidity here makes it awful at that temp. I'm from Texas, so I'm used to a drier climate with anywhere from it normally being over 100°F in the summer to getting as low as 5°F in the winter. The AC is a welcome necessity here in Brazil.

 

[Frenchy]

Yes, in the mid to upper 70s Fahrenheit, it doesn't want to engage. But man... This humidity here makes it awful at that temp. I'm from Texas, so I'm used to a drier climate with anywhere from it normally being over 100°F in the summer to getting as low as 5°F in the winter. The AC is a welcome necessity here in Brazil.

One thing I can say is that when the AC compressor doesn't engage, sometimes it can be another issue separate of the HVAC system that's sending a signal not to use it.

 

[airline tech]

Ok, I believe you are low on freon (most likely)
Reason - The system has a (Low Pressure) threshold it has to be above for the clutch to engage.
Temperature directly affects the (system pressure) , so system pressure @ 75 deg, is too low for the clutch to engage, when it warms up above 75 deg, it hits the minimum low-pressure point, and it engages
Basically, its just at that (perfect level) for you to see the (difference)

Other: Possibles - Failing Pressure Switch (Not reading correct pressure) or a bad Ambient Temp Sensor - (Does the Sync Screen or IPC display the correct temp?)

You could hook ap a scan tool and find all the related PIDs for the AC, there are a number of PIDs like what I posted above for (AC Clutch is inhibited for reason xyz) as I only posted 2 of them.

You can also view the (Pressure Switch) PID and also hook up a gauge set and compare actual gauge pressure to the reported pressure - this would be a good indicator if the pressure switch of reporting false pressure.

Minimum Pressure is around 42 PSI - Threshold for engagement, if below it will not engage
Note: The PID will normally read 14.7 PSI higher than the manifold gauge pressure if comparing.

For Brazil - and using 80 Deg F and 30-60% Humidity -with AC Clutch Engaged -
Discharge Pressure should be between 185 and 230 PSI (Approximate)

So, to highlight:
Pull up the PIDs for the system and better to do it @ known issue temperature and look at the AC Pressure PID - if below 42 PSI -This is why it's not engaging and as well check all the AC (Inhibited) reasons - it has one specifically for Low Pressure.

I have been working on building a (PID Reference) Database of normal for ALL PIDs and will be setting up some (Custom-Ref) PIDs as well, including all the AC System in one set and many others such as the - Transmission (Test Drive) PID Monitor for a ref point of what we should be seeing during the drive - in an attempt to highlight exactly what is happening as far as pressure when the transmission starts the (Harsh Shifts) - just for a knowledge addition and curiosity.

anyway, here is a couple pages of the complete (PCM) database run @ Idle parameters and note AC was off and only using heat -so the 68.44 PSI is just static system pressure with the current ambient temp and engine bay temp from idling.

 

[Frenchy]

Ok, I believe you are low on freon (most likely)
Reason - The system has a (Low Pressure) threshold it has to be above for the clutch to engage.
Temperature directly affects the (system pressure) , so system pressure @ 75 deg, is too low for the clutch to engage, when it warms up above 75 deg, it hits the minimum low-pressure point, and it engages
Basically, its just at that (perfect level) for you to see the (difference)

Other: Possibles - Failing Pressure Switch (Not reading correct pressure) or a bad Ambient Temp Sensor - (Does the Sync Screen or IPC display the correct temp?)

You could hook ap a scan tool and find all the related PIDs for the AC, there are a number of PIDs like what I posted above for (AC Clutch is inhibited for reason xyz) as I only posted 2 of them.

You can also view the (Pressure Switch) PID and also hook up a gauge set and compare actual gauge pressure to the reported pressure - this would be a good indicator if the pressure switch of reporting false pressure.

Minimum Pressure is around 42 PSI - Threshold for engagement, if below it will not engage
Note: The PID will normally read 14.7 PSI higher than the manifold gauge pressure if comparing.

For Brazil - and using 80 Deg F and 30-60% Humidity -with AC Clutch Engaged -
Discharge Pressure should be between 185 and 230 PSI (Approximate)

So, to highlight:
Pull up the PIDs for the system and better to do it @ known issue temperature and look at the AC Pressure PID - if below 42 PSI -This is why it's not engaging and as well check all the AC (Inhibited) reasons - it has one specifically for Low Pressure.

I have been working on building a (PID Reference) Database of normal for ALL PIDs and will be setting up some (Custom-Ref) PIDs as well, including all the AC System in one set and many others such as the - Transmission (Test Drive) PID Monitor for a ref point of what we should be seeing during the drive - in an attempt to highlight exactly what is happening as far as pressure when the transmission starts the (Harsh Shifts) - just for a knowledge addition and curiosity.

anyway, here is a couple pages of the complete (PCM) database run @ Idle parameters and note AC was off and only using heat -so the 68.44 PSI is just static system pressure with the current ambient temp and engine bay temp from idling.

Another trick that can be used is with basic pressure gauge with everything not running. Believe it or not system pressure should be at ambient temperature assuming that the system is full.

Also keep in mind that perhaps the PCM does have a code in it or some kind of condition not allowing the AC compressor to come on.

 

[airline tech]

Here are a couple more from my Autel:

 

[skrumpe]

The OP is Not in North America.
78F is not sub-zero

I was NOT addressing that issue, I was addressing the function of a pressure switch on the system. I was also pressed for time and unfortunately couldn't go further into the OP's problem. Most likely due to loss of refrigerant or some electrical issue that would have to be traced to find the cause.

 

[Grandaccess]

Yes, in the mid to upper 70s Fahrenheit, it doesn't want to engage. But man... This humidity here makes it awful at that temp. I'm from Texas, so I'm used to a drier climate with anywhere from it normally being over 100°F in the summer to getting as low as 5°F in the winter. The AC is a welcome necessity here in Brazil.

All Our humidity here is on the ground, the prediction is 135 inches for the season 2 years ago we got 41 inches in two days LOL ya we made national news
my driveway is 400' so 400' x 8'wide and 3'deep is 12,800 cubic feet to move

 

[smittybr]

Ok, I believe you are low on freon (most likely)
Reason - The system has a (Low Pressure) threshold it has to be above for the clutch to engage.
Temperature directly affects the (system pressure) , so system pressure @ 75 deg, is too low for the clutch to engage, when it warms up above 75 deg, it hits the minimum low-pressure point, and it engages
Basically, its just at that (perfect level) for you to see the (difference)

Other: Possibles - Failing Pressure Switch (Not reading correct pressure) or a bad Ambient Temp Sensor - (Does the Sync Screen or IPC display the correct temp?)

You could hook ap a scan tool and find all the related PIDs for the AC, there are a number of PIDs like what I posted above for (AC Clutch is inhibited for reason xyz) as I only posted 2 of them.

You can also view the (Pressure Switch) PID and also hook up a gauge set and compare actual gauge pressure to the reported pressure - this would be a good indicator if the pressure switch of reporting false pressure.

Minimum Pressure is around 42 PSI - Threshold for engagement, if below it will not engage
Note: The PID will normally read 14.7 PSI higher than the manifold gauge pressure if comparing.

For Brazil - and using 80 Deg F and 30-60% Humidity -with AC Clutch Engaged -
Discharge Pressure should be between 185 and 230 PSI (Approximate)

So, to highlight:
Pull up the PIDs for the system and better to do it @ known issue temperature and look at the AC Pressure PID - if below 42 PSI -This is why it's not engaging and as well check all the AC (Inhibited) reasons - it has one specifically for Low Pressure.

I have been working on building a (PID Reference) Database of normal for ALL PIDs and will be setting up some (Custom-Ref) PIDs as well, including all the AC System in one set and many others such as the - Transmission (Test Drive) PID Monitor for a ref point of what we should be seeing during the drive - in an attempt to highlight exactly what is happening as far as pressure when the transmission starts the (Harsh Shifts) - just for a knowledge addition and curiosity.

anyway, here is a couple pages of the complete (PCM) database run @ Idle parameters and note AC was off and only using heat -so the 68.44 PSI is just static system pressure with the current ambient temp and engine bay temp from idling.

Thank you, very much for the info! My initial thoughts were refrigerant as well. However, I didn't want to jump to that conclusion if it could be something else simpler. My ambient air temp seems to be reading correctly on the display. I will check the system pressure next and go from there. I appreciate it!

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