A/C works one day and not the next

[Mhad84]

New poster here. Not a mechanic. I learn from youtube but cannot figure this out. I have a 2018 Explorer XLT, 3.5L. Front and rear a/c system. My freon has been checked and is full with no leaks anywhere. My compressor turns on, fuses and all have been checked. One day I will get in and turn on the a/c and it is good and cool. Next day it blows 75 degrees out of the vents. When it is cool the compressor kicks on and off as normal. When it blows 75, the compressor kicks on and just stays on and never shuts off. I was told to check the pressure switch but read in a different forum that this year model doesnt have that anymore. Can anyone make any suggestions on what to look for next???

 

[dvdswan]

Sounds like a software issue.

 

[FordFlintrock]

New poster here. Not a mechanic. I learn from youtube but cannot figure this out. I have a 2018 Explorer XLT, 3.5L. Front and rear a/c system. My freon has been checked and is full with no leaks anywhere. My compressor turns on, fuses and all have been checked. One day I will get in and turn on the a/c and it is good and cool. Next day it blows 75 degrees out of the vents. When it is cool the compressor kicks on and off as normal. When it blows 75, the compressor kicks on and just stays on and never shuts off. I was told to check the pressure switch but read in a different forum that this year model doesnt have that anymore. Can anyone make any suggestions on what to look for next???

You should have a Variable Control Valve controlled compressor not a CCOT design that cycles clutch on and off. Normal state for yours is clutch engaged especially from your locale in the south. Variable control valve system takes inputs such as ambient, cabin air, H/side pressure, evap temp and converts it into a compressor duty cycle on how much refrigerant is being pumped.
When working one day with clutch cycling it is prolly hitting a pressure or temp limit which then as a fail safe cycles the clutch.
One needs a live data scan tool to see what readings are in spec and are not.

 

[Mhad84]

You should have a Variable Control Valve controlled compressor not a CCOT design that cycles clutch on and off. Normal state for yours is clutch engaged especially from your locale in the south. Variable control valve system takes inputs such as ambient, cabin air, H/side pressure, evap temp and converts it into a compressor duty cycle on how much refrigerant is being pumped.
When working one day with clutch cycling it is prolly hitting a pressure or temp limit which then as a fail safe cycles the clutch.
One needs a live data scan tool to see what readings are in spec and are not.

So like the first response I got? Software issue?

 

[Mhad84]

Sounds like a software issue.

Sounds like a mechanics work and not work from my garage

 

[FordFlintrock]

Software issue possible. Hardware/wiring issue likely.

 

[ProjectSHO89]

Software issue? No. It's simply doing what it has been told to do.

Most likely, the VCV is not being activated as FordFlintrock mentioned. You need a scan tool to see what is being input to the PCM and to see what the PCM is outputting.

 

[peterk9]

Sounds like a mechanics work and not work from my garage

Welcome to the Forum.
Please report back when/if a resolution has been found. Thanks.

Peter