SERVICE MANUAL FOR 6700, 7000, 8000 & 9000 SERIES AIR CONDITIONERS (MECHANICAL CONTROLS ONLY) FOR WALL MOUNT THERMOSTATS AND LOW VOLTAGE CONTROL CIRCUITS, REFER TO THEIR APPROPRIATE MANUALS FOR ELECTRICAL CHECKOUTS ON DELTA T AND DELTA TX AIR CONDITIONERS, REFER TO MANUAL R-332 (2-86)
PREFACE !WARNING - SHOCK HAZARD! This service manual is primarily intended for the use of qualified individuals specially trained and experienced in the service of this type of equipment and related system components. TO PREVENT THE POSSIBILITY OF SEVERE PERSONAL INJURY, DEATH OR EQUIPMENT DAMAGE DUE TO ELECTRICAL SHOCK, ALWAYS BE SURE THE POWER SUPPLY TO THE APPLIANCE IS DISCONNECTED BEFORE DOING ANY WORK ON THE APPLIANCE.
TABLE OF CONTENTS Basic Components and Their Functions Refrigeration System Diagram I. Refrigeration Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II. Air Handling Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 III. Electric Power Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 IV. Tools And Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BASIC COMPONENTS AND THEIR FUNCTIONS REFRIGERATION SYSTEM DIAGRAM DISCHARGE LINE SUCTION LINE COMP.
systems exists from the discharge port of the compressor to the cap tube. The low side is from the cap tube to the compressor cylinders. The dividing points then are the cap tube and compressor cylinders. The purpose of this part of the Service Manual is to acquaint the Service Technician with the system components so that when he has a problem, he can intelligently analyze and isolate the problem and efficiently correct it. 1.
5. saturation temperature, we call its condition sub-cooled liquid. Suction Line The suction line is the tube which carries the superheated vapor refrigerant from the evaporator to the compressor. 6. During all of the three processes in the condenser (desuperheating, condensing, sub-cooling), the refrigerant gives up heat; but most of the heat is given up during the condensing process. Compressor The compressor is called a hermetic compressor which means that it is completely sealed (welded together).
The power supply to the air conditioner must be wired through a circuit breaker or time delay fuse. The power supply must be 20 amperes and 12 AWG wire minimum. Any size an on-board motor generator, its wiring may be identical to the commercial power described above. There are, however, some motor generators on which both the current carrying leads are insulated from the ground.
condition can be analyzed by using an ohm meter. Be sure to remove all the leads from the compressor terminals before making this check. through the condenser coil. 1) If the resistance between any two terminals is 0 ohms, the motor windings are shorted. An important step in installing a replacement fan motor is to check the direction of rotation before it is installed. On all models, the condenser fan pulls the air through the coil.
. Good Capacitor Run Capacitors If the capacitor is good, the indicator will move from infinity (the left side), towards zero ohms and slowly return back to infinity. Reverse the leads and test again. The result should be the same. The purpose of the run capacitors is to give the motors starting torque and to maintain high power factor during running. The run capacitors are always connected between the start and run or main terminals of the motor.
connected in series with the start winding and it gets the generated voltage of the start winding portion of the compressor motor. This generated voltage is much higher than line voltage and varies with the speed of the motor. Therefore, since the relay is designed to open the contacts at 75% of normal running voltage (measured between terminals #5 and #2), the contacts will open (thus disconnect the start capacitor) at approximately 75% of normal running speed.
1. second) if there is one volt of pressure. Ammeter And Its Use An ammeter is an instrument for measuring electric current. Current electricity is actually electrons moving from one atom to another through a conductor. In order to intelligently use electricity, we must have a measurement of a quantity of electrons. An ohm meter is really a resistance meter that is calibrated in ohms.
terminals, but we know by referring to the wiring diagram, that the black wire is the common terminal, the red wire is the start terminal and the white wire is the run terminal. accurate to within a fraction of an ounce to prevent damage to the compressor and insure proper performance. Systems must not be charged to a certain amperage pull. They must not be charged to certain suction line temperature. Notice that when we are using an ohm meter, the power must be turned off.
1. Most all electronic leak detectors are very sensitive and are field reliable. A word of warning – do not “give it a whiff of refrigerant” as a test to see if it is working because its sensitivity and life expectancy diminishes as it is exposed to refrigerant. like, how hot was the weather, what time was it, etc. He is a rich source of information. Listen to everything he says. You will compliment him and he will help you to identify the problem.
2. “The selector switch could be open.” Rotate the selector switch and check for continuity between the appropriate terminals. Terminals Switch Position L-1-3 L-1 L-2 L-1-4 L-2-4 Lo Heat Lo Fan Hi Fan Lo Cool Hi Cool 2. This problem is easy to find and it is usually corrected by opening the discharge louvers. 3. “The fan could be at fault.” A mechanical problem such as the wheel (squirrel cage) loose on the shaft is usually rather obvious.
1. Answer: 1. “The selector switch may be open to the compressor.” “The voltage could be low – ” a) Check the voltage between #1 on the overload switch and the “R” terminal of the compressor while it is not humming. This voltage must be 115 volts domestic USA models or 240 volts export/overseas models. No less than minus 10% is allowable. b) Check the voltage from “C” or “R” of the compressor while it is humming (trying to start). The latter reading will probably be lower, but it still must be 103.
Problem Answer: 5. 1. “The power is getting to the compressor.” 2. “The start circuit is starting the compressor OK.” 3. “The capacitors and relay are providing the starting torque.” Compressor trips breaker or thermal current overload. Compressor trips circuit breaker or thermal current overload immediately (no hum). Note that this problem is different from the previous one in that in the previous problem, the compressor did hum for several seconds.
The customer turns the system to fan/low or fan/high and nothing happens. When he turns the selector switch to “Cool”, the compressor starts but still no fan. Problem Question: The customer says he gets inadequate cooling even though he has several times set the thermostat down to call for a lower temperature until it is now all the way down to the lowest possible setting. 10. “What could cause the fan to be dead?” Answer: 1. “The selector switch could be open.
Question: “What could cause the compressor to draw overcurrent or to overheat?” in coming to a conclusion. The indications of non-condensables in the system are: Answer: 1. 2. “Dirty condenser coil.” a) Overcurrent Check the appearance of the coil. If it is coated with lint, cottonwood fuzz, leaves, etc., it is insulated and it cannot give up its heat to the outside air.
6. “Plugged up cap tube.” entering the return air grille of the air conditioning unit. A cap tube can become stopped up by oil sludge or contaminants in the system. This will only occur if the system has been open to allow moisture or other contaminants to enter the system or if the compressor has been overheated for a lengthy period of time. It is difficult to determine the difference between a stopped up cap tube and a low charge because the symptoms will be nearly the same.
TYPICAL WIRING DIAGRAMS 6700 SERIES AIR CONDITIONERS & CEILING ASSEMBLIES 20
6798-7XX, 6798A7XX SERIES 6799-7XX, 6799A7XX SERIES 6799-8XX SERIES AIR CONDITIONERS & CEILING ASSEMBLIES 21
7000 & 8000 SERIES 6799A8XX SERIES 6799B8XX SERIES AIR CONDITIONERS 22
CEILING ASSEMBLY WIRING DIAGRAMS 6759, 7000, 8000 SERIES COOL ONLY 6759, 7000, 8000 SERIES HEAT/COOL 23
WIRING DIAGRAM FOR 9000 SERIES ROOF MOUNT AIR CONDITIONERS WIRING DIAGRAM FOR 9330X715, 9330X716 HEAT/COOL CEILING ASSEMBLIES 24
WIRING DIAGRAM 9330X713, 9330X714 COOL ONLY CEILING ASSEMBLIES 25
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