SUBCOURSE EDITION OD1750 A REFRIGERATION AND AIR CONDITIONING IV (EQUIPMENT COOLING) [...]... absorption air conditioning 2 The absorption system is one of the simplest of all types of automatic air- conditioning systems Though this machine has few moving parts, it has an immense cooling capacity We shall discuss in this chapter terminology, identification, and function of unit components; starting and operating procedures; and maintenance of the absorption system 5 Terminology, Identification, and. .. break the connection and make the necessary repairs 8 Cleaning the expansion valve strainer To clean the expansion valve strainer, you must close the liquid line shutoff valve and pump down the system to 2 p.s.i.g Disconnect the valve and plug the tube ends Remove the screen and clean it with a recommended cleaning solvent After the screen is clean and dry, reinstall it in the valve and connect the valve... capacity and the discharge valves check properly, you must remove the head and valve plate and check the valves physically 17 Disassembly, inspection, and reassembly of valve plates Pump down the compressor to 2 p.s.i.g and remove the compressor head capscrews Tap the head with a wooden or plastic mallet to free it if it is stuck and remove the cylinder head 18 Remove the discharge valves and valve... call is received from Building 1020 with a complaint of no air conditioning The system uses two D/X coils and two solenoid valves Which component should you check before troubleshooting the solenoid valve control circuit? (Sec 1, Par 14) 8 What type compressor must be used when twoposition control of a D/X coil and modulating control of a face and bypass damper are employed to control air temperature?... dioxide (40 p.s.i.g.) and check all the joints with a soap solution Release the pressure and repair any leaks that may have been found After the leaks have been repaired, charge the system with the recommended refrigerant to 10 p.s.i.g Add enough dry nitrogen or carbon dioxide to build the pressure to 150 p.s.i.g and leak test with a halide leak detector Purge the system and repair all leaky joints... it, purge the compressor, and start the unit Figure 20 shows two different types of strainers, basket and disc, and their location in the compressor motor 10 Purging noncondensable gases Noncondensable gases (air) collect in the condenser (water-cooled) above the refrigerant The presence of these gases cause excessive power consumption, a rise in leaving water temperature, and high compressor discharge... the compressor suction and discharge valves and connect your gauge and manifold to the appropriate compressor gauge connections The next step is to connect a refrigerant drum to the middle manifold hose Open the drum valve and purge the hoses, gauges, and manifold Then tighten all the hose connection Turn the suction shutoff valves a couple of turns from the backseat position and open the drum valve... deck and the middle bowed upward 21 Worn valves may be reconditioned by lapping them, using a fine scouring powder and a piece of glass Mix refrigerant oil with the powder to form a liquid paste Then move the valve in a figure 8 motion over the paste and glass After the valve is reconditioned, clean and reinstall it 22 Use new valve plate and cylinder head gasket when you install the valve plate and. .. p.s.i.g for R-12 and 200 to 230 for R-22 4 Servicing and Troubleshooting 1 We have covered several service techniques in the previous section that relate to installation, including leak testing, dehydrating, and charging into the low side as a gas and into the high side with liquid We shall now go further into servicing as it relates to disassembly, inspection, and reassembly of individual components... pump and contamination of the indicator, you must install shutoff valves in the suction line at the vacuum pump and the vacuum indicator When shutting off the pump, close the indicator valve and pump valve, and then turn off the pump Now we are ready to dehydrate the system 21 Procedure for dehydrating the system Connect the pump and vacuum indicator to the system Put a jumper line between the high and . SUBCOURSE EDITION OD1750 A REFRIGERATION AND AIR CONDITIONING IV (EQUIPMENT COOLING)