Tool Briefing 52 PTEN FEBRUARY 2017 www.VehicleServicePros.com t Fig. 2: Used for “contact” testing of components when measuring between two points on the same component is necessary, this Fluke Thermocouple Module (No. TK80) allows techs to convert a DMM to a temperature probe. of components when measuring between two points on the same component is necessary (see Fig. 2). • Thermal imager – a relatively new technology that is making its many uses known in the automotive repair industry. This tool has many uses in HVAC, such as obtaining temperature of components within the dash without removing dash panels to get at the component (see Fig. 3). There are some rule of thumb temperature tests you can perform to determine if the system is functioning normally, or use to determine what some of the likely causes of failure are. Starting with an analog or digital thermometer, check and record the ambient air temperature one to two feet in front of the radiator. Then insert a thermometer in a dash vent on both sides of the vehicle (see Figs. 4 and 5). With the air conditioner on high, record both temperatures. Remember to place a fan in front of the vehicle to allow sufficient air flow across the condenser and radiator. The results of these tests will determine if the system is cooling sufficiently and if it is delivering cooled air equally side to side. The outlet vent temperature on most vehicles will be 30 degrees F or more lower than ambient temperature on a well-functioning system. It should also be noted because ambient air temperatures can affect how well refrigerant condenses; you cannot expect outlet temperature Use a DMM with the temperature probe to test the inlet and outlet evaporator lines. They should read within +/- 5 degrees F of each other. If the temperature variance is higher or lower it may be due to a low refrigerant charge, orifice tube issues or too much oil; all of which can cause problems later. Using a thermal imager, such as the Snap-on EETH300, in the shop has proved to be increasingly useful for vehicle diagnosis. Because it may be a relatively new tool to you, it is a good idea to start building a library of “known good” and faulty components. Over time as you utilize this tool, you will be able to have a visual display of temperature variances and be able to obtain them much faster than before. This tool has advantages such as having the ability to “see through” other components like the dash to visualize warmer components and record their temperature (see Figs. 8 and 9). With HVAC issues, this can help diagnose faulty evaporators, heater cores and blend doors, among other components. Thermal imagers are also quickly becoming the “go-to” tool for testing heated and cooled seats, along with heated windows and mirrors. Without a thermal imaging tool, it is difficult to see if these systems are working correctly, if at all. To sum it up, accept the fact that technology changes. With those changes, it is necessary to utilize new tools and access the abundance of information in order to keep up with technology and to diagnose and repair vehicles efficiently and effectively. It is important to thoroughly review all aspects of the repair. Having the proper tools in your arsenal helps to ensure the repair has been diagnosed and fixed correctly. t Fig. 7: Another view of the user conducting a condenser line contact temperature test. B.Hoyland to be at 58 degrees F on a 110 degrees F day because you were able to reach that temperature on a 90 degrees F day. It goes without saying a quick and safe way to obtain temperatures of underhood components with a running engine is an infrared thermometer. Using an infrared thermometer equipped with a laser pointer ensures you are measuring the components you desire (see Fig. 6). We used the Mastercool 5224 Infrared Thermometer to test the compressor, condenser and evaporator. Measuring the compressor in the center of the housing away from hoses and lines should be within 20 degrees F of other engine components. Higher temperatures may indicate a low oil charge or problems within the compressor. Using the infrared thermometer, test the condenser to check if there is a sufficient temperature drop between the inlet and outlet temperatures. There should be between a 20 degrees F and 50 degrees F drop in temperature. If not, higher than 50 degrees F readings can indicate a low charge or other issues, while under a 20 degrees F drop can indicate insufficient air flow. Due to the radiator being so close to the condenser, it may be difficult to differentiate radiator temperature from the condenser. In this case, use a DMM with a temperature probe on the condenser lines (see Fig. 7). This method of “contact” testing may be more accurate as it will read temperatures of only the component(s) you are testing. Circle 155 on card, or enter at “e-inquiry” on VehicleServicePros.com
Professional_Tool_And_Equipment_News_February_2017
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