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What temperatures can tell you about the climate system

By autotech-nath on June 20, 2017
Keeping a car’s AC system running at peak performance means monitoring the health of the components through a variety of information, including temperature. By knowing where and what to measure, you can troubleshoot the AC system cost-effectively and quickly.
One way of conducting temperature diagnostics on the climate system is through the temperatures difference method – measuring the condenser’s inlet minus the outlet temperatures and then comparing it to the appropriate range based on the manufacturer’s suggested temperature points. This helps to highlight poor system performance due to high pressure within that part of the system. Michael Ingvardsen, Nissens Training Manager and climate specialist, says: “When customers take their vehicles in for service, they know their AC system isn’t working correctly, but they don’t know why. Nissens trains diagnosticians to take the information they get from customers and use that to aid their search for the answers and come to a conclusion quickly. By training people in the most effective ways of using loop components temperature diagnostics, mechanics can quickly and easily find the answers, and solve the problem. This creates happy customers for the mechanics – and happy
customers tend to return.
Screen Shot 2017-06-20 at 20.35.40
When it comes to temperature, any number of causes can affect it. If the measured temperature falls outside either end of the recommended temperature ranges, it could be due to:
• Restricted airflow from internal clogs or contamination
• Faulty valves
• Leakage in the loop
• A malfunctioning condenser, AC fan or fan clutch
• Lack of lubrication
Looking elsewhere within the AC system loop, measuring temperatures at various points and components can also give you important information about the health of the system. Temperatures may not directly reflect refrigerant charge levels, but overcharging can generate higher pressure and heat, which can then affect the compressor (among other components), and even lead to failure.
An example of how temperature diagnostics can help the mechanic can be seen if the evaporator begins to freeze, bringing temperature below prescribed levels. Here, air or moisture in the AC loop should be considered as a possible culprit, along with possible improper or contaminated refrigerant.
“What will signal a problem for both drivers and mechanics within the AC system loop, is temperature: for the driver, a slow down or lack of cooling coming from their AC system within the cabin, while the mechanic will notice temperature measurements outside the manufacturer’s suggested range,” says Michael.
“These incorrect measurements will signify different problems, depending on their location, including malfunctioning or failed condensers or compressors, faulty valves stuck in a particular position, or even an excess level of refrigerant due to overfilling. Excess refrigerant can lead to higher pressure within the loop components, driving the temperature outside the prescribed range. It is incredible how much detailed information temperature can give us about the system.”
Whenever you have a vehicle with a cooling issue, measuring temperature outputs of the system can provide a quick and cost-effective method of diagnosis for a wide range of problems. Based on the temperature measurements and further investigation, and along with replacement of any faulty components, Nissens argues that a thorough flushing and cleaning of the system should be performed to ensure the system is free of contaminants or particles that can cause similar issues over time.
To easily identify the correct temperature ranges for the climate system, and causes for abnormalities in these
temperatures, Nissens has developed a free technical temperature diagnostics poster that provides a complete
overview of possible causes and solutions.
The poster can be downloaded for free at:


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