(FACTORY SPECIFICATION PARTS) as replacements. Use of “fits-all,” or “look alike” parts could result in early parts failure, safety hazard, or substandard perfor- mance of a WHIRLPOOL appliance. It could also result in an unnecessary repeat of your repair efforts.
Fundamental Properties Of Gas ... 1-1 Measuring Heat Energy ... 1-1 Fuel Types ... 1-2 Characteristics Of Gas Fuels ... 1-4 Distribution Of Natural Gas ... 1-5 Distribution Of L.P. Gas ... 1-6 Pressure Regulators ... 2-1 Functions ... 2-1 Regulator Operation ...
Natural And L.P. Gas Conversion ... 5-1 General ... 5-1 Converting A Pressure Regulator ... 5-2 Converting Cooktop Burners ... 5-2 Converting An Oven Burner ... 5-3 Converting An Oven Thermostat ... 5-3 Burner Flame Adjustment ... 5-4 Performance Check ... 5-5 Testing The Components ...
This program is designed to teach the servicer basic skills in handling common service procedures for gas ranges. This program does not cover the diagnosis and repair of all range problems and components, (oven liner, wiring harness, etc.). PROGRAM OBJECTIVE Upon completion of this program, the participants will be able to identify the location of major range components, as well as diagnose problems, and remove and repair the components causing the problem.
FUNDAMENTAL PROPERTIES OF GAS MEASURING HEAT ENERGY When burning a gas fuel, heat energy is produced. This heat energy is usually expressed in British Thermal Units, or B.T.U.’s. One B.T.U. is equal to the amount of heat needed to raise one pound of water one degree Fahrenheit (see Figure 1-1).
Gas Fuels are categorized as follows: #1 = Natural Gas #2 = Mixed Gas #3 = Manufactured Gas #4 = Liquefied Petroleum Gas #1 — NATURAL GAS Natural Gas is found underground. It is referred to as “wet gas,” because it contains heavy hydrocarbons, such as propane and butane.
Category 1 – Natural Gas – Contains Methane & Ethane. Sour Natural Gas Contains Hydrogen Sulfide Which Corrodes Copper & Brass. It Has A Heat Valve Of 900 to 1200 B.T.U. Per-Cubic-Foot. Specific Gravity Is 0.65 To 0.70. Category 3 –...
CHARACTERISTICS OF GAS FUELS Each of the four types of gas has a specific boiling point (see Figure 1-2). The boiling point is referred to as the temperature where gas turns from a liquid to a gas at atmospheric pressure. If temperatures fall below the freezing point (32˚F), the liquid will not turn into a gas, and there will be no flame.
DISTRIBUTION OF NATURAL GAS Utility companies send natural gas through underground pipes, called “mains.” The gas in these mains is pressurized at between 25 and 60 pounds-per-square-inch (psi). Branches carry the pressurized gas to the various buildings, and are connected to gas meters. The meters decrease the main’s gas pressure to 7 inches water column pressure (1/4 pounds) for use by the appliances inside the buildings (see Figure 1-6).
DISTRIBUTION OF L.P. GAS For Liquid Propane (L.P.) gas, appliances generally operate on gas pressure rated at between 10 and 12 inches water column pressure. Each appliance usually has its own pressure regulator to more accurately meet the designed requirements (see Figure 1-8). L.P.
PRESSURE REGULATORS A Gas Pressure Regulator is a mechanical device that performs the following two functions: • Reduces higher incoming gas pressure to a desired lower outgoing gas pressure. • Maintains a steady, even flow of gas as it leaves the regulator. The Appliance Pressure Regulator is used to further reduce the gas pressure to the desired level for the particular application (see Figure 2-1).
REGULATOR OPERATION The pressure of the gas coming into the pressure regulator pushes against a spring-loaded diaphragm, forcing it upward. The diaphragm spring puts pressure on the diaphragm. In order to control the flow rate, the diaphragm has a tapered plug suspended from it to restrict or increase the gas flow pressure (see Figure 2-3).
The amount of spring tension applied to the diaphragm determines the output pressure of the regulator (see Figure 2-5). Gas Inlet A manual gas shutoff on some pressure regulators will allow the gas to be turned off to the oven burners during service to allow gas flow to the cooktop to remain on.
Pressure regulators contain an air vent in the upper chamber to allow a free flow of air in and out of the chamber during operation (see Figure 2-7). The vent’s secondary purpose is to safely control the flow of gas to the atmosphere (200cc-per-hour or 7 BTU-per-hour) in case the diaphragm ruptures.
The model/serial plate on the gas range (see Figure 2-8) provides information about the proper water column pressure. Whirlpool ranges operate on 4 inches water column on natural gas, and 10 inches WCP on L.P.
Observe the movement of the water in the manometer. The gas pressure is read by adding the water movement in both legs of the tube, as shown in Figure 2-10. It should measure within the pressure rating stated on the rating plate. The Magnehelic gauge (see Figure 2-11) can also help measure gas pressure.
GAS VALVE—The gas valve controls the gas flow to the individual burners. The valves on all Whirlpool ranges are push-to-turn types to keep them from being turned on accidentally. When the valve is turned on, gas flows through the valve and out an orifice.
A typical Whirlpool gas valve and its component breakdown is shown in Figure 3-2. The gas valves are used to control the gas flow to the top burners. The gas valves are usually mounted to the top of the manifold pipe with a screw and rubber washer. The gas valve housing contains a hollow gas control seat.
An orifice is an opening used to control the direction and amount of gas that is discharged to a burner. Orifices are available in different sizes and shapes and can be removed and replaced without replacing the valve. PLUG-TYPE ORIFICES The cooktop burner orifice uses a plug-type orifice, as shown in Figure 3-5.
L.P. AND NATURAL GAS ORIFICES The actual size and configuration of each orifice depends on several factors. The most important factor, however, is the type of gas that will be used by the gas range system. The two most frequently used types are: liquefied petroleum (L.P.) gas, and natural gas. L.P.
UNIVERSAL ORIFICE—OVEN APPLICATION Gas cooking systems for both L.P. gas and natural gas can be used without changing orifices by using a univer- sal orifice. The universal orifice consists of an L.P. gas insert that is threaded into a cap orifice. This insert is actually an orifice itself.
GAS VALVE ORIFICE DIAGNOSTICS A gas valve orifice is often a source for gas range problems. Some of the problems that arise with an orifice are as follows: The orifice may become clogged from dirt, or slag in the gas lines. The result will be an over- restricted gas flow, causing the mixture to become too “lean”.
To understand how a burner operates, it is important to understand the following terms (see Figure 3-9): Gas: The fuel used by the burner, either natural or L.P. Primary Air: The air mixed with the gas in order to make the gas combustible. Secondary Air: The supplemental, or ambient air, surrounding the flame.
The Cooktop Burner Assembly controls the combustion of gas and directs its flame (see Figure 3-11). Burners are manufactured from galvanized steel and have common component parts: An Air Shutter to control the amount of primary air to be mixed with the gas. A Venturi to provide a pathway for gas to flow to the burner from the orifice.
BURNER HEAD When gas leaves the orifice, it passes through the venturi, and is forced into the burner head. As the gas passes between the orifice and the burner head, primary air is mixed with the gas to form a combustible mixture. The burner head disperses the gas/air mixture for ignition. In addition to the burner ports at the top of the burner head, there are also ports along the side of the burner, called charge ports and climber ports .
FLAME CHARACTERISTICS A Properly Burning Flame A properly burning flame has an inner cone, an outer cone, and an outer envelope. These three parts should be definable and distinguishable, although the outer envelope may not be easy to see. (see Figure 3-14). The inner cone is the point where the air/gas mixture ignites and the combustion process begins.
The inner-cone combustion process will occur in increased levels, and will release more of the harmful by-products, CO and Aldehydes. The level of secondary air will no longer be enough to convert these chemicals into the safe by-products CO dangerous chemicals released into the room. NOTE: It is normal for the burners without mixing tubes to have blowing flames during the first minute of operation.
The over-fueled burner has more of a normal flame structure and less of a blowing noise than a burner with too much primary air. The easiest way to determine whether the burner is over-fueled is to vary the air shutter opening size. If the flame length can be reduced to the correct size and structure by adjusting the air shutter, then the problem is not an over-fueled burner.
In the case of an over-fueled burner, the excessive length of the flames can result in the quenching at the oven flame spreader or top burner grate even though the flame spreader and grate may be at the proper distance. Check for this before adjusting the burners. When quenching occurs, (see Figure 3-20), the customer may complain of a chemical odor.
IMPROPER FLAME DIAGNOSTICS For any of the improper flames discussed, refer to the following chart for the appropriate corrective actions. In most of the malfunctions described thus far, the burner flames will change character- istics when a problem develops. However, there are times when the symptom of a burner problem is an unusual noise.
CLEANING THE BURNERS The most common burner maIfunction is clogging due to excess dirt and debris, which can enter the burner through the burner ports. This excess dirt can block one or several of the ports so that the burner will have trouble lighting, or will not light at all. In this case, the burner ports must be cleared using a pin (see Figures 3-21 and 3-22).
STANDING PILOT IGNITION SYSTEM OPERATION The ignition system provides heat, which is the third element necessary for combustion. Whirlpool ranges use two different processes to provide this element. The first process is a standing pilot ignition, and the second is an electronic ignition.
When the gas control valve is turned on, gas flows to the burner head, and out the ports. There are ports at both the top and side of the burner head, as shown in Figure 3-25. The side ports direct gas to a flash tube , where it is drawn through the tube to the pilot flame, where it is ignited inside the tube.
ADJUSTING THE PILOT FLAME HEIGHT A pilot that frequently blows out may be set too high, or too low. To adjust the pilot flame to the correct height, perform the following steps: Turn off the controls and prop open the cooktop. Using a screwdriver, turn the needle valve screw slowly in the direction necessary to set the size of the pilot flame, as shown in Figure 3-27.
CLEANING THE PILOT The small opening of a pilot can easily become clogged with dust, grease, or food, preventing proper gas flow. A pilot that will not light, or will not stay lit, may simply need to be cleaned. To clean the pilot, insert a straight pin into the pilot opening, as shown in Figure 3-28, and move it up and down gently, being careful not to enlarge or deform the opening.
The ignitor switches are mounted on the stem of each burner control valve, and are rotary-actuated. There are two types of switches used on Whirlpool ranges. One is for a 90˚ valve, shown in Figure 3-29, and the other is for a 220˚ valve. Each gas valve has its own ignitor switch. The ignitor switches are wired in parallel.
The Ignitor Spark Module is a solid-state device that is used to provide high voltage for the top burner ignitors (see Figure 3-30). Whenever the ignitor module is energized by one of the ignitor switches, a solid state circuit and pulse transformer within the module electronically increases the constant AC line voltage to periodic high voltage pulses, and sends these pulses to all of the ignitor electrodes at the same time.
Refer to Figure 3-32 for the following sequence. CONVENTIONAL BURNER When a main burner control knob q is turned to the “lite” position, the gas valve r opens, and gas flows through the pressure regulator s into the manifold t through the open valve. As gas passes through the valve and its orifice, it is directed into the venturi u, where it mixes with primary air to create the proper mixture necessary for combustion.
Refer to Figure 3-33 for the following sequence. SEALED BURNER When a main burner control knob q is turned to the “lite” position, the gas valve r opens, and gas flows through the pressure regulator s into the manifold t through the open valve. As gas passes through the valve and its orifice, it is directed into the venturi u, where it mixes with primary air to create the proper mixture necessary for combustion.
ELECTRONIC IGNITION DIAGNOSTICS Problems with electronic ignition systems usually occur in one of two ways: the electrode will not spark, or the sparking will not stop. If the ignitors are in series, and one is not sparking, none will spark. Also, all spark ignitors use the same ignitor spark module, but different switches.
THE OVEN BURNER SYSTEM STANDING PILOT IGNITION The complete Standing Pilot Ignition System (see Figure 4-1) is controlled by two very important mechanical components. The first is a thermostat that is mounted on the manifold pipe and accessible to the customer, and the other is an oven safety valve that controls the gas flow into the oven burner.
The Thermostat is a hydraulic valve that has two separate gas lines and a sensing bulb (see Figure 4-2 ). The pilot gas line maintains a pilot flame in the oven, and the main gas line provides gas to the oven safety valve. The sensing bulb is a mercury-filled tube that controls the thermostat to open or close the gas lines, and release gas from the manifold pipe to the oven safety valve.
The interaction between the thermostat and the safety valve is very important and critical to the operation of the oven. The thermostat provides two separate functions each time it is turned on, but first, we need to know what the thermostat does when it is in the “OFF” position. Even with the thermostat in the “Off”...
As this is taking place, the thermostat also opens the main gas line, and provides gas to the safety valve (see Figure 4-6). As soon as the safety valve is hydraulically opened by the signal from the sensing bulb, gas is released from the safety valve to the oven burner, and ignited by the heater pilot flame.
NOTE: The thermostat used in the Standing Pilot range needs to be converted if L.P. gas is being used. A "Nat" or “L.P.” setting is located on the front face of the thermostat (see Figure 4-8 and its inset). LIGHTING THE OVEN PILOT To light the pilot, perform the following steps (see Figure 4-9): Turn off all the range controls.
The Glo-Bar Ignition System (see Figure 4-10) is a 120-volt electrical system that consists of three important components. The three components, a thermostat that is controlled by the customer, an ignitor and a safety valve, both located inside the oven, create a very efficient system that is safe and dependable.
The Thermostat contains a set of contacts that open and close, (see Figure 4-11A), depending on the temperature selected by the customer, and the temperature monitored in the oven cavity. When the thermostat is turned to the “ON” position, contacts within the thermostat close to complete an electrical circuit (see Figure 4-11B).
The Oven Ignitor is made of a silicon-carbide material (see Figure 4-13). When voltage is applied to the ignitor, it heats up to 2000˚F. As its temperature increases, its resistance decreases, allowing 2.5 to 3.0 amps to flow to the bimetal in the safety valve. This measurement is critical to the proper operation of the ignitor.
The oven uses a Single Safety Valve that is bimetal-operated (see Figure 4-16). It has one gas inlet and one gas outlet, for the combination Bake and Broil burner. The safety valve uses an electrically-operated device at the gas outlet to control the gas flow to the oven burner. The device consists of an electric heater coil wrapped around a bimetal strip.
When current flows through the ignitor, heat is applied to the bimetal strip. The amount of heat necessary to warp the bimetal enough to open the valve requires 3.0 amps of current flow in the circuit (see Figure 4-18). The reason the valve is designed not to open below 3.0 amps, is to insure that the temperature of the oven ignitor is above 1800˚F before the valve opens.
When the thermostat senses that the selected oven temperature is reached, its internal contacts open, as discussed earlier, and the electrical circuit is terminated (see Figure 4-20). The bimetal cools and closes the safety valve to shut off the gas flow to the oven burner. This cycling of the electrical system continues throughout the cooking cycle.
SELF-CLEANING SYSTEM All Whirlpool Self-Cleaning Gas ranges use two burners in the oven to provide even heating during the Bake and Broil functions, and higher temperature during the Self-Clean cycle (see Figure 4-22). To provide each of these features, the system incorporates a bake burner that operates just like the Glo-Bar Ignition System already discussed, plus an additional broil burner that provides the benefit of broiling inside the same oven cavity.
Self-Clean ovens use a dual safety valve that is bimetal-operated. The dual valve has one gas inlet and two gas outlets; one for the Bake burner and the other for the Broil burner (see Figure 4-23). It uses two identical electrically-operated devices, one for each outlet, to control thc gas flow. The devices consist of an electric heater coil wrapped around a bimetal strip.
The electronic board is constructed with individual relays to operate the Bake, Broil, and Self Clean functions independently of each other. The Microcomputer board electrical diagrams (see Figure 4-26) show how opening and closing the relays operate the various customer-selected cycles. OVEN CONTROL TRANSFORMER LATCH SOLENOID...
By the construction of the relays, both the Bake Function (see Figure 4-27), and the Broil function (see Figure 4-28), can not operate at the same time. The normally-closed position of the opposite relay is needed to complete the circuit. BAKE P3-1 BROIL...
F0 = If the most recent F-code is recalled via user input, F0 indicates no failure has occurred. F1 = Electronics Subsystem Failure. Replace electronic control board. E0 = EEPROM communication error. E1 = EEPROM checksum error. E2 = A/D converter error (is there an error bit in the micro?; does this mean lost a voltage rail?).
600˚F. The system can be activated by the consumer manually, using a lock lever, or electrically. Whirlpool ranges utilize an electronic locking system to assure that the range will not operate unless the oven door is safely locked during high temperatures.
When the solenoid plunger extends, two things happen (see Figure 4-30). As the latch solenoid locks the door, it also activates the two door latch switches. Both door switches are normally-open switches. As the solenoid moves to lock the door, the switches toggle, and: a) Open the oven light circuit so that the light cannot be operated during the Clean function.
When the oven temperature reaches 600˚, the oven door cannot be opened until the oven cools down to below 550˚. At that point, the latch solenoid relay will close for just a second, and provide a 120 VAC pulse to the latch solenoid (see Figure 4-31). This unlocks the door and toggles the door latch switches to their normal state.
NATURAL AND L.P. GAS CONVERSION Ranges must be adjusted when going from one type of fuel to another due to the characteristics of the gases. This means that, for efficient combustion, air must be mixed with the gas. The amount of air to be mixed with the amount of gas is called the air-to-gas ratio .
CONVERTING A PRESSURE REGULATOR By varying the tension of the regulator spring, the gas outlet pressure can be controlled for natural and L.P. gas. The regulator spring tension is adjusted by reversing the spring retainer (see Figure 5-1A) or the regulator cap (see Figure 5-1B). Gasket Natural Gas Intlet...
CONVERTING AN OVEN BURNER The oven burners use universal orifice hoods. To convert the oven burners, use a 1/2 " combination wrench and turn the orifice hood 2 to 2-1/2 turns so it is just against the L.P. orifice inlet. DO NOT OVERTIGHTEN the hood, or you will damage the inlet.
BURNER FLAME ADJUSTMENT After converting the range to L.P. gas operation, it may be necessary to adjust each burner flame (cooktop and oven burners). A proper cooktop burner flame should be approximately 5/8 " high and have a well-defined blue flame. The oven burner flame should be approximately 3/4 " high and have a distinct blue flame.
TESTING THE COMPONENTS WARNING LABELS This manual is intended for factory-service technicians only. We recommend that customers DO NOT service their own units, because of the complexity and risk of high-voltage electrical shock. The following information should be read carefully. Page 6-1...
GENERAL INFORMATION When diagnosing a problem, always begin by checking the range for the proper line voltage, open fuses, and defective components. New ranges that have been in operation for only a short time should be checked for loose connections or incorrect wiring. When using a test meter, use one that has a sensitivity of 20,000 ohms-per-volt, or greater.
TESTING AN OVEN GLO-BAR IGNITER If the glo-bar ignitor (see Figure 6-2) does not glow, perform the following steps to test it: Turn off the gas and electrical power to the range. Disconnect the oven igniter quick-disconnect plug from the main harness connector. Connect an ohmmeter across the wire ends or terminals of the glo-bar.
TESTING AN IGNITOR SWITCH The ignitor switch (see Figure 6-3A) is located on the gas control valve stem and closes when the knob is turned to the LITE position (see Figure 6-3B) to provide power to the ignitor spark module. To test a switch: Turn off the gas and electrical power to the range.
TESTING AN OVEN LIGHT SWITCH The oven light switch can be a rocker-type, (see Figure 6-4A), or a pushbutton-type (see Figure 6-4B) switch. The rocker switch is manually operated, and the pushbutton switch is operated by the oven door. The pushbutton switch may have more that two terminals, depending on the model. The terminal callouts for the two types of pushbutton switches are shown below.
TESTING AN OVEN TEMPERATURE SENSOR Some oven controls use an oven temperature sensor (see Figure 6-5) to operate the bake, broil, and self-clean functions. The oven temperature sensor is a “Resistance Temperature Detector (RTD)” and is composed of a stainless steel tube with a thin film of platinum on the end. The sensor is usually located inside the oven cavity at one of the upper rear corners.
TESTING AN OVEN DOOR LATCH Gas ranges that have a self-clean feature incorporate an oven door latching system, (see Figure 6-6), which locks the oven door during the self-clean cycle. The door latch assembly consists of a solenoid and one or two switches. Figure 6-6 To test the solenoid windings, perform the following steps: Turn off the gas and electrical power to the range.
To test the switch(es): Turn off the gas and electrical power to the range. Disconnect the wires from the switch terminals. Set the ohmmeter to the R x 1 position. Connect one of the ohmmeter leads to the common (COM) terminal. Touch the other ohmmeter lead to the normally-open (N.O.) switch terminal.
TESTING A GAS SAFETY VALVE Some gas ranges use an electrically-controlled gas safety valve to control the flow of gas to the oven burner. The electric safety valve controls the gas flow by means of a bimetal-controlled diaphragm. Self-clean models have a single inlet, dual outlet, bimetal-operated safety valve. To prevent miswiring, the bake and broil terminals are sized differently.
TESTING THE GAS CONTROL VALVES The top burner gas valves control the gas flow to the top burners. The valve is a barrel and core, grease sealed, locking type valve (see Figure 6-12). Before the stem can be turned, it must be pushed in to unlock the valve.
TESTING THE GAS PRESSURE REGULATOR The pressure regulator is a mechanical device that reduces the higher incoming gas pressure to a lower outgoing pressure, and maintains a steady, even flow of gas. The pressure regulator has one outlet that is connected directly to the gas safety valve. The inlet has a manual shutoff valve so that the gas to the safety valve can be turned off (see Figure 6-13).
TROUBLESHOOTING CHART PROBLEM Gas odor. Gas odor with all pilots lit or with electronic ignition. Surface burner does not light. Surface burner pilot does not stay lit. Surface burner flame low or uneven. Surface burner flame too high, noisy, or blowing. Surface burner flame yellow or sooty.
PROBLEM Oven burner does not light. Oven burner pilot does not stay lit. Oven does not hold set tempera- ture so that oven bakes unevenly. Self-cleaning oven does not clean. POSSIBLE CAUSE Pilot light out. Pilot light set too low. Clock timer set improperly.