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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3375
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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Keep getting a AC5 fault code on my APU, serial numberJA:

Customer Question

keep getting a AC5 fault code on my APU
JA: What is the complete model and serial number of your machine?
Customer: serial number(###) ###-####JA: Are you fixing this yourself? What have you tried so far?
Customer: item 900217m
JA: Anything else you want the equipment mechanic to know before I connect you?
Customer: I reset the system and restarted a few times, keeps going back to this code, just wondering what to check next
Submitted: 1 month ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 1 month ago.

My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

What you are getting is ACS, not AS5. It means Air Conditioning Sensor. The refrigerant level is low in the system or one of the sensors for the refrigerant is shorting. Most likely it is a low refrigerant issue. It uses 134 like the truck does so you can have the truck stop, like a T/A repair it without the need to go to Thermo King.


You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see, touch, smell, hear the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.

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