III-80
Troubleshooting
& Service Procedures
• Troubleshooting Overview
• Understanding System Function
• A Troubleshooting Example
• Manifold Gauge Set Installation
• Troubleshooting by Manifold Gauge Set Readings
• Review of Frequent Problem Areas
• Conclusion
Can you fix an air conditioner or heater system without finding and correcting the
cause of the problem? You bet you can! It happens every day and it·s not good for
business. Here is an example. A truck pulls in off the road and the operator asks to have
his rig serviced in a hurry. He tells you the air conditioner isn·t cooling like it should
and dashes into the restaurant for lunch.
You tip the hood, and check the sight glass on top of the receiver-drier. You see
bubbles, not a lot but a fairly constant stream of them. It is obvious the system is low
on refrigerant so you hook up the manifold gauge set, purge the gauge set hoses of
air, and add refrigerant until the sight glass clears. Then you check evaporator tem-
perature and it·s OK. The air conditioner is repaired right? Wrong! What you did is
add refrigerant and the problem went away. You did not find and fix the cause of the
problem.
Component failure in an air conditioning system may be the result of a problem
elsewhere in the system. For example, a belt or clutch failure might be caused by a
dirty condenser restricting air flow and increasing head pressures. High head pressures
commonly create problems with other system components. Take time to look beyond
the obvious for a potential hidden problem.
Troubleshooting Overview
Troubleshooting includes collecting enough information to locate the cause of the
problem, then correcting the problem and its cause by replacement, adjustment, and/or
repairing. You begin by gathering information from the most to the least important
sources.
Starting with the most important:
1. Your personal knowledge and experience with AC systems.
2. The vehicle operator's knowledge and experience—question him or her.
3. The work order.
4. Good test equipment and the HVAC system
The routine you follow when troubleshooting should proceed from the most to least
productive way of locating the problem and fixing the cause.
To Next Page
Loading...
Need help?
General
