Ford AC trouble

Caleb Diagnostician Mishawaka, Indiana Posted   Latest  
Updated
Pico Technology
Electrical
HVAC
2007 Ford F-150 Lariat 5.4L (5) 4-spd (4R75E)
No Ac Compressor Operation

I cant believe I am asking a question about AC but I guess there is a first time for everything. I was called to look at this 2007 F-150 for no AC compressor engagement. When I initially looked at this truck there were codes for power steering pressure switch and no comm with ABS module. Visual inspection of the power steering line was the wrong one and had no fitting to install a pressure switch and the connector was hanging. I thought maybe this would inhibit AC operation. Second I found the IGN fuse blown to the ABS module which also powers the lowside AC pressure switch. The shop owner installed a new power steering line with a sensor and that fixed the power steering issue. A new fuse restored comm with the ABS module but still no compressor engagement. At this point after looking at some data, with nothing sticking out like a sore thumb I told him I needed IDS before I would go any further. Well fast forward 2 months and I now have IDS and he still has the truck. I noticed that the PCM had junkyard writing, I made sure it had the correct VIN in it from the windshield and was too the latest calibration. All okay. Anyway looking at data with IDS here is what I have. Also as a disclaimer all the PID values I am going to list have been double checked in generic for substituted values and there is no issues there. 

ECT ,CHT,AAT,IAT,PSP,Interior temp sensor all read correctly. AC pressure sensor is 93 psi. The wide open throttle PID shows normal with no AC cut. The AC relay command is always off. The AC relay permission always shows allowed. This truck has an automatic temp control head on the UBP network. It has a perfect 0-12 volt square wave when checked at the DLC and control head. The IPC is the gateway between the CAN Bus and the UPB network. There are no PIDs in the IPC for an AC request, only for rear defrost. When looking at data in the HVAC module the PID shows you pushed the AC button. The AC indicator also turns on and off accordingly on the HVAC control screen with the button pushes. I can ground the AC relay control wire right at the PCM and the compressor works fine. I cant seem to find a way to command the AC compressor relay with IDS or 3 different aftermarket scan tools. Im not sure where to go from here. Id like to tell him to put in a new OE PCM. Id also like to try an IPC. I think he is going to try a used control head because they are cheap. What am I missing?? I need some sort of network decoder to see if the AC request is or isnt getting to the PCM. Thanks guys this was long winded, I hope it makes sense!!

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Chris Technical Support Specialist
Commack, New York
Chris Default
   

Manual Ac control communicates with the IPC via a dedicated wire, (I believe it grounds it), Auto temp control communicates via network message. The as built configuration may not be set correctly in the ipc. Try to configure the IPC with asbuilt. if the asbuilt function is not in the ids menu, got to the utilities page and select update/special function and enter code 53061. then perform a PMI…

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Tommy Owner/Technician
Houston, Texas
Tommy Default
 

I have two suggestions. First does it have an evap temp sensor and if so is it reading properly.. Second do and KOEO test this should cycle the a/c compressor clutch relay during the test, at least you can see if pcm can control the a/c relay Good Luck

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Chris Technical Support Specialist
Commack, New York
Chris Default
 

You could also command the compressor on in datalogger if you have IDS there should be an AC CMD # pid listed. Pids with # are able to be active commanded.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Excellent point on the KOEO . Thanks Tommy.

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John Owner
Medford, New York
John Default
 

Caleb, I second Chris' suggestions. Make sure you have correct IPC for this vehicle as well. Had one a couple of weeks back that drove me nuts and had wrong year IPC. You can extract IPC part number from IDS session log. I typically do this because the IPC stickers fade(unknown how that happens) or get worn off.

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Justin Mobile Technician
Herriman, Utah
Justin Default
 

I have seen more than once a replacement IPC that came “preprogrammed“ from the ford dealer that after replacement had no ac as the complaint. Doing as built coding on the IPC fixed all of them. No codes. Not updating the software, but as built coding being the fix.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Update
 

Thanks Chris,John, and Justin. To run As built on the IPC actually crossed my mind and I forgot. Thanks for getting my head out of the sand!!

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Dave Mobile Technician
Ironton, Ohio
Dave Default
 

Look at the sun load pid. If it is reading a crazy number, disconnect the security light up on the top of the dash, it pops right out. The sun load sensor is built into the unit. I have had one that drove me nuts and the owner had already spent 2G's trying to get it fixed.

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Caleb: I don't disagree with the other suggestions. I also can't remember if this applies to your vehicle but the year is appropriate. Go into Programmable Parameters and look for an A/C selection. If it is there, verify that it is marked as "Equipped". This used to be a common issue after replacing an IPC, especially in the winter time. HTH, Guido

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Hey Anthony, I had a look at the Programmable Parameters Saturday but I dont think there was anything for that. I will definitely check when I go back.

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Glen Owner/Technician
Arthur, Illinois
Glen Default
 

Follow PPT test I (A/C is Inoperative Does Not Operate Correctly) Monitor the (ACCS) PCM PID reads ON when both of the following are met: The PCM receives an A/C request through the CAN bus and PCM receives voltage from the A/C cycling switch.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Thanks Glen. In my post I put AC compressor relay permission is allowed on scan data. Also the ACCS switch reads correctly.

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Glen Owner/Technician
Arthur, Illinois
Glen Default
   

ACCS pid reads ON or OFF?

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Honestly I don't remember on or off. However unplugging it AC permission is not allowed. When plugged in AC permission is allowed.

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Glen Owner/Technician
Arthur, Illinois
Glen Default
 

Just to be clear what is the "it" that was unplugged? Was this with the IDS? Just a thought if the ACCS pid actually is ON...wouldn't that imply that the cluster and related circuits are functioning as desinged? eg. A/C request is making it to the PCM

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Trying to learn along with this one Glen. What is the ACCS PID ? My two guesses are 1. - A/C Cycling Switch 2. A/C Commanded State. I know on my NGS when you highlight the abbreviation it has the translation at the bottom. thank you for your time.

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Jose Technician
Woodland, California
Jose Default
 

Had a similar issue with a Freestyle of similar year. It was the IPC as built data as previously mentioned by Chris

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Robert Owner
Holland, Michigan
Robert Default
 

We had similar problem with a Focus. If I recall the ac switch sent medium speed signal to cluster then cluster sent a high speed signal to pcm for relay operation only if temperature and pressure were a go. Pulled build data from Fords web site for cluster and now it works. No idea why it stopped working, car wash, vacuum static?? but has been working now for 8 months.

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Chris Technical Support Specialist
Commack, New York
Chris Default
 

We started seeing this issue with asbuilt mismatches around the era of the Ford Five Hundred. It seemed like there had to have been cluster replacements but I personally have seen them where the cluster looked original as could be, The difference in the HVAC trim level is whether the ac req from the HVAC module is a dedicated single signal wire or a networked message to the cluster to…

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Update
   

Alright, so I had a chance to get back yesterday and finish this thing. I pulled the cluster first to verify it was the correct part number for the VIN and it was. I programmed it with the original As-Built data with IDS and "Bam" right before winter the AC works now lol! Anyway wanted to mention that the door sticker shows the truck was built in Canada and it also had a Customs Import sticker…

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