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Andy
Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1571
Experience:  International trucks, International, Maxxforce and Cummins engines, diagnostic, electrical, Hvac and refrigeration repairs
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I have a 2012 M2 112 business class truck having a/c

Customer Question

Hello I have a 2012 M2 112 business class truck having a/c problems , no power to compressor. do you have the wiring diagrams for this truck
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Andy replied 1 year ago.
Thanks for requesting me ! Can we start with the full 17 digit vin number please?
Customer: replied 1 year ago.
1fydc3bs8cdbh8683
Expert:  Andy replied 1 year ago.
Thanks ! i will look it up for you !
Expert:  Andy replied 1 year ago.
Your vin is not working in my system . Can you tell me which engine you have in it ?
Customer: replied 1 year ago.
cummins isl
Expert:  Andy replied 1 year ago.
Thanks I will look that up !
Expert:  Andy replied 1 year ago.
Ok Here is your AC wiring diagram ! I enlarged it but in doing so , it becomes too large so I had to split it into two halves . You just need to print both halves and paste them together to view the whole diagram . https://www.dropbox.com/s/0j30br60kzdzzt5/ac1.png?dl=0 https://www.dropbox.com/s/ph9rln8ig7aawuw/ac%202.png?dl=0 Please let me know if you need something ! And please do not forget to rate my service to you ! That is the only way that I am rewarded on here . Thanks.
Customer: replied 1 year ago.
thank you ,can you explain the theory & operation of this system?As in inputs/outputs & so on
Expert:  Andy replied 1 year ago.
With the engine on , and AC set to max , if you unplug the Cluch connector, do you have 12 volts ? Positive on one wire and ground on the other ?
Expert:  Andy replied 1 year ago.
In the diagram , you will see that the binary switch basically watches the pressures and if too low or too high , will cutoff the positive power to the clutch to prevent compressor damage . We need to check at the binary switch .
Expert:  Andy replied 1 year ago.
Assuming that system is full of freon and there are no leaks , if you have no power at the compressor clutch , then go to the binary switch and check for power there on pin A. If there is power on pin A , then jump power from pin A to pin B on the plug at the binary switch momentarily just to see that the clutch is engaging . If it is , replace the binary switch .Thanks
Customer: replied 1 year ago.
Thanks, ***** ***** traced power supply all the way back to the hvac module in the dash & can apply ground to the 338j circuit & the compressor engages. We replaced hvac module thinking there was a problem there not sending signal to bulkhead connector but still nothing. Seems as tho there is a missing input but I am having trouble pinning it down.
Expert:  Andy replied 1 year ago.
Ok do you have a good ground at the clutch connector ? You should be checking continuity between the engine ground somewhere clean and the clutch connector negative pin . Resistance should be low like less than 1-2 ohms .
Expert:  Andy replied 1 year ago.
Do you still need help ?
Expert:  Andy replied 1 year ago.
Hi there ! Have you been able to check the ground side for continuity ?
Expert:  Andy replied 1 year ago.
Do you still need help ? Happy to assist further if needed . Let me know . Please do not forget to rate my service to you at the end of this session. Feedback is important and bonus is appreciated too . Thanks

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