No power at the A/C clutch?

JAMESZZZ91

MEMBER
2020 FORD F-250
6.2L
V8
4WD
AUTOMATIC
200,000 MILES

I have two ford f250 trucks, a 2020 and 2021. Both trucks currently have no power at the A/C compressor fuse therefore the clutch will not engage. I understand the system is cutting power to the fuse due to both of these trucks having a low side pressure over 100psi. I just had the 2021 vacuumed, tested and recharged to the exact level required. It worked great for 2 weeks and now it is no longer working. Same issue, clutch won't engage, no power at clutch fuse and very high pressure on low side. I've replaced the pressure switch, did nothing. The 2021 has had ac vacuumed, tested and recharged like 6-10 times since we bought it, always works great for a few weeks then no power. It seems none of the shops or the dealer can resolve this problem. Our 2020 has been recharged 2-3 times and is experiencing very similar issues as the 21, no power at fuse and high pressure on low side. I know there is no leak as when we vacuum the lines, they have the same amount of freon that was installed, it's just the pressure keeps building until the PCM cuts power to the clutch. I don't know why this is happening or how to fix this, tired of spending money at shops that are supposed to be knowledgeable, but we all know they just want your money to hit a few buttons on an ac machine to get you out the door and back in when it fails. I don't think the A/C expansion valve, orifice tube could be blocked since they are newer trucks. I know the A/C pumps and clutch plates are working fine, I know there is freon in the system, but I don't know why the pressure keeps building up. Please for the love of God someone give me some insight here before I cut the tops off these trucks and use them as burn barrels. Possibly the A/C expansion valves?

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
42,949 POSTS

Hello,

Can I ask if when the AC is running does the cooling fan come on? Also, did anyone do a CAN scan of the HVAC system? You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

If the engine is running hot or overheating the PCM will shut the AC system down FYI. If the system is overcharged this will happen as well. If they are using a cheap gauge set the readings could be off. Please go over this video to help see what the pressures should be and how to do the job correctly:

https://youtu.be/4EqdrBVb0sY?si=eQq3HwT-zAAd9MXB

NOTE: Compressor control and the evaporator temperature are a function of many parameters, not a straight on off to avoid freezing the evaporator. The PCM monitors multiple temperature sensors correlation (AAT, CHT, ECT IAT, MAF...) as applicable. The PCM runs this logic after an engine off and a calibrated soak period, typically 6 to 8 hours. This soak period allows the Ambient Air Temperature (AAT) sensor and the other temperature sensors to stabilize and not differ by greater than a calibrated value, typically 18 C (64.4 F). If a sensor input is found to be reporting a temperature imbalance the PCM does not allow the A/C clutch to engage. For more information on PCM sensors, Refer to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

There is a pressure transducer that can go bad and cause this issue, here is the location so you can check it out it. Check out the images (below). Let us know how it goes.

Images (Click to make bigger)