Taurus Car Club of America : Ford Taurus Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1 (Edited)
Please help with where to troubleshoot, here is the background:
-AC compressor was stuck and ripped the serpentine belt.
-Replaced AC compressor and dryer. recharged the system and all worked.
-Drove it for 2k miles and then no ac again.
-All fuses under the hood and inside are good.
-Tried to jump start the clutch is is engaging, tried to jump the low and high side pressure switch and nothing happen but went into the fuse box and jump start with taking the relay off and use a paperclip, then the clutch engages. replaced the relay for the ac clutch and still no luck.
Gave up and went to the shop, they diagnosed that the PCM ground is bad, they said that the PCM fault caused grounding ac control circuit not working and recommended to replace the PCM. Well, did replace the PCM and still the issues is the same! the system is fully charged, and blowing cold air when clutch engages.
At this point, I really don't know what else to check. I was charged $128 for diagnosis which did not help either, they wanted $900 for the PCM but was able to replace way a lot cheaper. I am not sure how effective then if I go back and toss another diagnosis fee for just another trial and error! Any help will really be appreciated. Thanks
 

·
Registered
Joined
·
387 Posts
I would recommend something simple which you may doubt will work. If the ground for the PCM is bad, stop and clean the ground for the PCM. Replacing the PCM will not correct a bad PCM ground. Chartmaker and others convinced me to clean that ground and it cleared a PCM trouble code. The ground is to a painted surface. I followed instructions to clean the bolt and took sandpaper to create bare metal to ground. If you replaced the PCM you know where the ground is. While you are at it I would clean all the grounds. If you need a photo of the PCM ground I probably can provide one. Located at the firewall passenger side above the low pressure AC valve.

Scott
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
I would recommend something simple which you may doubt will work. If the ground for the PCM is bad, stop and clean the ground for the PCM. Replacing the PCM will not correct a bad PCM ground. Chartmaker and others convinced me to clean that ground and it cleared a PCM trouble code. The ground is to a painted surface. I followed instructions to clean the bolt and took sandpaper to create bare metal to ground. If you replaced the PCM you know where the ground is. While you are at it I would clean all the grounds. If you need a photo of the PCM ground I probably can provide one. Located at the firewall passenger side above the low pressure AC valve.

Scott
Hey Scott, thanks for your inputs.
Sure I can give it a try, No I don't know where is the grounds you are referring to; however, the ground code was gone after replacing the PCM. All PCM codes are cleared. Only code I currently have is B1352 Ignition Key in Circuit failure but I don't think it is related to ac!
Here is a couple of updates as of today. when cut key on Run and turn the ac on.
Tested the AC clutch plug and there was no voltage.
Read the ACCS PID using FORscan and it was off, jumped the low pressure switch and still the ACCS PID reads off!

Now when I unplug the high side switch and jump it, the fans start when the ac is on (still clutch is off) then when I jump start the ac clutch relay then the clutch starts and blows cold air. Now, from all of the above it seems that the PCM is not receiving ACCS signal which would allow the ac to turn on. Not sure really what to test at this point!

Thanks.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #4
Solved, replaced the cutoff switch on the high side and all worked afterwards! was wired that the old cut off switch was working sometimes, seems like it was about to fail.
 
1 - 4 of 4 Posts
Top