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S e r v i c e L i t e r a t u r e
ML193UHEK series units are high-efficiency gas furnac-
es manufactured with Lennox DuralokPlus
steel clamshell-type heat exchangers, with a stainless
steel condensing coil. ML193UHEK units are available in
heating input capacities of 30,000 to 110,000 Btuh (8.8 to
32.2 kW) and cooling applications from 2 through 5 tons
(7.0 through 17.6 kW). Refer to Engineering Handbook for
proper sizing.
Units are factory equipped for use with natural gas. A kit
is available for conversion to LPG operation. All ML193U-
HEK units are equipped with a hot surface ignition system.
The gas valve is redundant to assure safety shut-off as
required by C.S.A.
The heat exchanger, burners and manifold assembly can
be removed for inspection and service. The maintenance
section gives a detailed description on how this is done.
The ML193UHEK can be "twinned" with a second unit.
Two units can operperate as one, in a shared duct system
controlled by a single thermostat. All specifications are
subject to change. Procedures outlined in this manual are
presented as a recommendation only and do not super-
sede or replace local or state codes.
WARNING
This furnace is equipped with an ignition control
factory enabled for use with A2L refrigerant systems.
Disabling the refrigerant detection functionality on
A2L system is prohibited by safety codes. Refer
to furnace installation instructions for refrigerant
system setup.
Table of Contents
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Optional Accessories
. . . . . . . . . . . . . . . . . . . . . . . . . . 3
Blower Performance Data
Twinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
I-Unit Components
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
II Placement and Installation . . . . . . . . . . . . . . . . . . . . 26
III-Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
IV-Heating System Service Checks
V-Typical Operating Conditions
VI-Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
VII-Low GWP Application . . . . . . . . . . . . . . . . . . . . . . . . . . 54
VIII-Sequence of Operation and Flow Charts . . . . . . . .. .57
IX-Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
UNIT INFORMATION
UNIT INFORMATION
ML193UHEK With R-454B SERIES UNITS
aluminized
™
. . . . . . . . . . . . . . . . . . . . . . 4
. . . . . . . . . . . . . . 46
. . . . . . . . . . . . . . . . . 50
100163
Improper installation, adjustment, alteration, service
or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional HVAC
instale (or equivalent), service agency or the gas
supplier.
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal
injury. Take care while handling this equipment and
wear gloves and protective clothing.
Page 1
ML193UHEK
WARNING
CAUTION
.
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Summary of Contents for Lennox ML193UHEK Series
- Page 1 ML193UHEK 100163 S e r v i c e L i t e r a t u r e ML193UHEK With R-454B SERIES UNITS ML193UHEK series units are high-efficiency gas furnac- es manufactured with Lennox DuralokPlus aluminized ™ steel clamshell-type heat exchangers, with a stainless steel condensing coil.
- Page 2 SP ECIF ICATIONS Model ML193UH ML193UH ML193UH ML193UH Heating 030XE36BK 045XE36BK 070XE36BK 090XE36CK Performance AHRI Reference No. 20256877 20256878 20256879 20256880 AFUE Input - Btuh 30,000 44,000 66,000 88,000 Output - Btuh 29,000 42,000 63,000 84,000 Temperature rise range - °F 25 - 55 30 - 60 40 - 70...
- Page 3 OPTIONAL A C C ESSORIES “B” Width Models “C” Width Models CABINET ACCESSORIES Horizontal Suspension Kit - Horizontal only 51W10 51W10 Return Air Base - Upflow only 50W98 50W99 High Performance Economizer (Commercial Only) 10U53 10U53 CONDENSATE DRAIN KITS Condensate Drain Heat Cable 6 ft.
- Page 4 BLOWER DATA ML193UH030XE36BK PERFORMANCE (Less Filter) Air Volume / Watts at Various Blower Speeds External High Medium-High Medium Medium-Low Static (Black) (Brown) (Blue) (Yellow) (Red) Pressure in. w.g. Watts Watts Watts Watts Watts 0.10 1403 1145 0.20 1386 1122 0.30 1361 1094 0.40...
- Page 5 B LOWER DATA ML193UH090XE36CK PERFORMANCE (Less Filter) Air Volume / Watts at Various Blower Speeds External High Medium-High Medium Medium-Low Static (Black) (Brown) (Blue) (Yellow) (Red) Pressure in. w.g. Watts Watts Watts Watts Watts 0.10 1442 1320 1172 0.20 1413 1289 1138 0.30...
- Page 6 BLO WER DATA ML193UH110XE60CK PERFORMANCE (Less Filter) Air Volume / Watts at Different Blower Speeds Bottom Return Air, Side Return Air with Return Air from Single Side Return Air − Air volumes in bold (over 1800 Both Sides or Return Air from Bottom and One Side. cfm) require Optional Return Air Base and field fabricated External transition to accommodate 20 x 25 x 1 in.
- Page 7 PARTS IDENTIFICATION FLEXIBLE NO-HUB EXHAUST COLLAR BURNER BOX ASSEMBLY TOP CAP GAS VALVE DuralokPlus HEAT EXCHANGER ASSEMBLY COMBUSTION AIR INDUCER BURNER ACCESS PANEL BAG ASSEMBLIES (shipping location) PRIMARY LIMIT COLD END BLOWER ACCESS HEADER BOX PANEL BLOWER COMBUSTION ASSEMBLY AIR PRESSURE SWITCH CONTROL BOX former, circuit breaker and interlock switch)
- Page 8 The 24 VAC secondary of the two systems must be in Twinning phase. All thermostat connections are made to one control The control board in this furnace is equipped with a provi- only. See diagram below. sion to ”twin” (interconnect) two(2) adjacent furnaces with The twinned furnace without thermostat connections is a common plenum such that they operate as one (1) large to have the call for heat supplied by an external 24VAC...
- Page 9 I-UNIT COMPONENTS 3. Circuit Breaker (CB8) A 24V circuit breaker is also located in the control box. The ELECTROSTATIC DISCHARGE (ESD) switch provides overcurrent protection to the transform- Precautions and Procedures er (T1). The breaker is rated at 3A at 32V. If the current CAUTION exceeds this limit the breaker will trip and all unit opera- tion will shutdown.
- Page 10 Indoor Blower Operation DIP Switch Settings TABLE 1 The heat fan-on time of 30 seconds is not adjustable The 1/4” QUICK CONNECT TERMINALS heat fan-off delay (amount of time that the blower oper- 120V HUM POWER FOR HUMIDIFIER (120 VAC ates after the heat demand has been satisfied) may be LINE INCOMING POWER LINE (120 VAC)
- Page 11 On Board Links Must NOT Be Cut To Select Thermostat Wiring Connections AC ON System Options Heat / Cool FURNACE OUTDOOR T'STAT TERM. STRIP UNIT DO NOT CUT ANY ON-BOARD LINKS FIGURE 3 On Board Links Must Be Cut To Select Wiring Connections Thermostat Heat Pump Options...
- Page 12 Single Stage, Constant, Torque, Non-Communicating 107792-XX FIGURE 6 Indoor Blower Speeds 1 - When the thermostat is set to “FAN ON,” the indoor blower will run continuously on the (FAN) speed when there is no cooling or heating demand. See table below for for allowable circulation speeds. 2 - When the ML193UHEK is running in the heating mode, the indoor blower will run on the heating speed (HEAT).
- Page 13 TABLE 4 Integrated Diagnostic Codes/Status of Equipment Code Diagnostic Codes/Status of Equipment Indoor Blower Operation: Continuous Fan only mode Defrost mode Idle mode (Decimal blinks at 1 Hertz -- 0.5 second ON, 0.5 second OFF). Cooling stage (1 second ON, 0.5 second OFF) 1 or 2 displayed / Pause / Repeat codes. Dehumidification mode (1 second ON, 1 second OFF) / Pause / Repeat Codes).
- Page 14 The sensor #1 is of a type not suitable for use in the application. incorrect Replace the sensor with a Lennox approved replacement part. This fault clears when a sensor suitable for the application is detected by the furnace control board, but blower will latch for a minimum of 5 minutes.
- Page 15 TABLE 4 Continued Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E164 Low GWP Test Low GWP Test mode activates by manually engaging Low GWP test button. Normal operations resumes and code clears automatically after 1-minute E200 Hard lockout - Rollout circuit open or previously Correct cause of rollout trip, or replace flame rollout switch.
- Page 16 Burner Box Assembly Burner Assembly Rollout Switch(s) Flame Sensor Ignitor Gas Valve Burner Box Front FIGURE 7 B-Heating Components (FIGURE 7) the burners. During operation, flame is sensed by current passed through the flame and sensing electrode. The ig- Combustion air inducer (B6), primary limit control (S10), nition control allows the gas valve to remain open as long ignitor, burners, flame rollout switch (S47), gas valve as flame signal is sensed.
- Page 17 Measuring Flame Signal Flame Signal In Microamps Normal Drop Out 0.5 - 1.4 Flame Sensor Wire Remove sensor from integrated control and connect alligator clip (−) to ame sensor lead. Multi−Meter Intergrated Control Set Dial to DC MICROAMPS Flame Sensor Terminal (−) T o Flame Terminal...
- Page 18 Test 1 Check ignitor circuit for correct resistance. Remove HSI/CAI 4-pin plug from control. Check ohms reading across terminals 2 and 4. Reading should be between 39 and 70 ohms. If value is correct, this is the only test needed. If the reading on the meter is not correct, (0 or infinity) then a second test is needed.
- Page 19 2. Heat Exchanger (FIGURE 10) Primary Limit Location and Heat Exchanger Units use an aluminized steel primary and stainless steel secondary heat exchanger assembly. Heat is transferred to the air stream from all surfaces of the heat exchanger. The shape of the heat exchanger ensures maximum effi- ciency.
- Page 20 -110 1.406” TABLE 6 8. Combustion Air Pressure Switch (FIGURE 12) Altitude Ft ML193UHEK series units are equipped with a differential 0-4500 4501-7500 7501-10000 Unit pressure switch located on the cold end header box. The switch monitors across the combustion air inducer orifice Set Point “w.c.
- Page 21 Measuring Pressure Differential Black Tubing (positive +) Red and Black Tubing or Red Tubing (negative -) To Cold End Header Box To Cold End Header Box Field Provided Tubing To Pressure Switch “+” High “-” 1 - Remove thermostat demand and allow unit to cycle off.
- Page 22 TABLE 7 Problem Corrective Action Check that the pressure switch is open without the com- Pressure switch stuck closed bustion air inducer operating. Replace if defective. Pressure switch does not close due to obstruction in vent Check for restricted vent. Remove all blockage. Check for pipe.
- Page 23 C- Blower Compartment BLOWER WHEEL REPLACEMENT IMPORTANT Center Blower Wheel in Blower Housing Each blower is statically and dynamically balanced as an assembly before installation in the unit. Units are equipped with a constant torque ECM motor. It has a DC motor coupled to an electronic control module both contained in the same motor housing.
- Page 24 Multi−Meter (set to V AC) Multi-met (set to VAC) "9A” Test 3 (if necessary) NOTE- Ignition control illustration is typical "7A” Check for 120 volts across terminals “L1” and “Neutrals” on the Turn power on to unit. Check for 120 volts integrated control.
- Page 25 Replacing the Motor Module approximately the same resistance within an ohm. 3 - Check to see if the blower wheel spins freely. NOTE - Not all motors have field replaceable control mod- ules. Only motors that utilize a 4 pin power connector and Motor Test 5 pin signal connector as shown below may have replace- able controls.
- Page 26 II-PLACEMENT AND INSTALLATION IMPORTANT Pipe & Fittings Specifications Exhaust and intake connections are made of PVC. Use PVC primer and solvent cement when using All pipe, fittings, primer and solvent cement must conform PVC vent pipe. When using ABS vent pipe, use with American National Standard Institute and the Ameri- transitional solvent cement to make connections to can Society for Testing and Materials (ANSI/ASTM) stan-...
- Page 27 TABLE 10 OUTDOOR TERMINATION USAGE* STANDARD CONCENTRIC Wall Kit 1-1.2 inch 2 inch 3 inch Flush Mount Kit 2 inch 3 inch Vent Pipe 71M80 69M29 Input Size Field 60L46 (US) 51W11 22G44 Dia. in. (US) (US) 44J40 (US) Fabricated 44W93 (US) (US)
- Page 28 Vent Piping Guidelines as a vacation home, make provisions for draining NOTE - Lennox has approved the use of DuraVent ® condensate collection trap and lines. Centrotherm manufactured vent pipe and terminations Exhaust Piping (FIGURE 24, FIGURE 26 &...
- Page 29 In some applications which permit the use of several dif- Which needs ferent sizes of vent pipe, a combination vent pipe may be most elbows? used. Contact Lennox’ Application Department for assis- Intake or tance in sizing vent pipe in these applications. exhaust? NOTE - The exhaust collar on all models is sized to ac- commodate 2”...
- Page 30 TABLE 12 Maximum Allowable Intake or Exhaust Vent Length in Feet NOTE - Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
- Page 31 TYPICAL EXHAUST AND INTAKE PIPE CONNECTIONS IN UPFLOW DIRECT OR NON-DIRECT VENT APPLICATIONS 2” EXHAUST EXHAUST INTAKE INTAKE 2” 2” 2” 2” 2” 3” 3” 030/045/070 Only 1−1/2” TRANSITION Exhaust 2” 6” Min Exhaust DO NOT transition from larger to smaller DO NOT transition pipe in horizontal runs from smaller to larger...
- Page 32 Intake Piping TYPICAL AIR INTAKE PIPE CONNECTIONS The ML193UHEK furnace may be installed in either direct HORIZONTAL NON−DIRECT VENT APPLICATIONS vent or non-direct vent applications. In non-direct vent ap- (Horizontal Right−Hand Air Discharge Application Shown) plications, when intake air will be drawn into the furnace from the surrounding space, the indoor air quality must be considered and guidelines listed in Combustion, Dilution and Ventilation Air section must be followed.
- Page 33 General Guidelines for Vent Terminations CAUTION In Non-Direct Vent applications, combustion air is taken If this unit is being installed in an application with from indoors and the flue gases are discharged to the out- combustion air coming in from a space serviced by an doors.
- Page 34 TABLE 14 Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For Winter Design Temperatures Single - Stage High Efficiency Furnace Winter Design Unit Input Size Vent Pipe Temperatures1 °F Diameter (°C) 1-1/2” 32 to 21 2 in (0 to -6) 2-1/2 in...
- Page 35 ‡ Permitted only if veranda, porch, deck or balcony is fully open NOTE - This figure is intended to illustrate clearance on a minimum of two sides beneath the floor. Lennox recommends requirement and does not serve as a substitute for avoiding this location if possible.
- Page 36 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of locally adopted installation codes. two sides beneath the floor. Lennox recommends avoiding this location if possible. FIGURE 34 Page 36...
- Page 37 Details of Intake and Exhaust Piping Terminations for TABLE 15 Direct Vent Installations Exhaust Pipe Termination Size Reduction NOTE - In Direct Vent installations, combustion air is taken ML193UHEK Model Termination Pipe Size from outdoors and flue gases are discharged to outdoors. *030, *045, *070 1-1/2”...
- Page 38 7 - If intake and exhaust piping must be run up a side wall to position above snow accumulation or other obstructions, piping must be supported. At 12” EXHAUST least one bracket must be used within 6” from the (305mm) VENT 5-1/2”...
- Page 39 FIELD FABRICATED WALL TERMINATION NOTE − FIELD−PROVIDED REDUCER MAY BE 2” (51mm) 3” (76mm) REQUIRED TO ADAPT Vent Pipe Vent Pipe LARGER VENT PIPE SIZE TO TERMINATION A− Minimum clearance above grade or average 12” (305 mm) 12” (305 mm) snow accumulation B−...
- Page 40 Crawl Space and Extended Horizontal Venting 12” (305mm) ABOVE AVE. Lennox provides kit 51W18 (USA) kit 15Z70 (Canada) to SNOW install 2” or 3” PVC exhaust piping through the floor joists ACCUMULATION and into the crawl space. See figure below.
- Page 41 If this is not pos- sible, a heat cable kit may be used on the condensate trap and line. Heating cable kit is available from Lennox in various lengths; 6 ft. (1.8m) - kit no. 26K68 and 24 ft.
- Page 42 CONDENSATE TRAP LOCATIONS Condensate Trap With Optional Overflow Switch (Unit shown in upflow position with remote trap) From Evaporator Coil HorizontalFurnace4” Min. to 5” Max.above FieldProvidedVent condensatedrain connection) Min. 1” Above Condensate Drain Connection 1” Min. 2” Max. FurnaceCondensate DrainConnection *5’...
- Page 43 Furnace with Evaporator Coil Using a Separate Drain (Unit shown in horizontal left-hand discharge position) Field Provided Vent Evaporator (4” min. to 5” max. above Coil condensate connection) 4”min 5”max 5’ max. PVC Pipe Only Condensate Drain Connection (Trap at coil is optional) Drain Pan Piping from furnace and evaporator coil must slope down a minimum 1/4”...
- Page 44 TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC Optional Condensate Drain Connection Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) 90° Street Elbow 3/4 inch PVC (not furnished) Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) Condensate Drain Connection In Unit 1 (25 mm) Min.
- Page 45 III-START-UP 2 - Set the thermostat to the lowest setting. 3 - Turn off all electrical power to the unit. A-Preliminary and Seasonal Checks 4 - This furnace is equipped with an ignition device 1 - Inspect electrical wiring, both field and factory which automatically lights the burners.
- Page 46 Use of a All units are C.S.A. design certified without modifications. specialty Gas Leak Detector is strongly recommended. It is available through Lennox under part number 31B2001. Refer to the ML193UHEK Operation and Installation In- See Corp. 8411-L10, for further details.
- Page 47 Manifold Pressure Measurement Follow the steps below and use FIGURE 57 as a reference. Gas manifold Kit 10L34 provides additional components if needed. 1 - Connect the test gauge positive side “+“ to manifold pressure tap on gas valve. 2 - Tee into the gas valve regulator vent hose and connect to test gauge negative “-”. 3 - Start unit and let run for 5 minutes to allow for steady state conditions.
- Page 48 E-Proper Combustion F-High Altitude Furnace should operate minimum 15 minutes with correct NOTE - In Canada, certification for installations at eleva- manifold pressure and gas flow rate before checking com- tions over 4500 feet (1372 m) is the jurisdiction of local bustion.
- Page 49 G- Proper Ground and Voltage 2 - In addition, measure the AC voltage from Line Hot to Line Neutral (spade terminals) on the integrated WARNING control. See FIGURE 58. This voltage should be in the range of 97 to 132 Vac Electric Shock Hazard.
- Page 50 V-TYPICAL OPERATING CHARACTERISTICS C-External Static Pressure 1 - Tap locations shown in FIGURE 60. A-Blower Operation and Adjustment1 2 - Punch a 1/4” diameter hole in supply and return NOTE- The following is a generalized procedure and does air plenums. Insert manometer hose flush with not apply to all thermostat controls.
- Page 51 Condensate Hose Screens (FIGURE 61) the data given in the appropriate Lennox Product Specifications bulletin. Additional information is provided Check the condensate hose screens for blockage and in Service and Application Note ACC002 clean if necessary.
- Page 52 17 - Mark and disconnect any remaining wiring to Condensate Hose Screens heating compartment components. Disengage strain relief bushing and pull wiring and bushing through the hole in the blower deck. 18 - Remove the primary limit from the vestibule panel. 19 - Remove top cap screws to allow top cap to be tilted upward to allow clearance for removing heat Hose...
- Page 53 40 - Secure burner assembly to vestibule panel using 7 - Disconnect and label ground wire from burner/ four existing screws. Burners are self aligning to manifold assembly. center of clam shells. 8 - Remove four screws that secures burner/manifold 41 - Reconnect gas supply line to gas valve.
- Page 54 VII- Low GWP Application WARNING For use with Lennox approved evaporator coil and LGWP sensors only. Use original manufacturer recommended LGWP sensors if using non Lennox approved evaporator coil. CONNECTING THE FURNACE CONTROL BOARD SENSOR. See FIGURE 64 and follow steps below: FIGURE 63 1 - Route sensor wire #1 through provided grommet.
- Page 55 FURNACE CONTROL BOARD LOW GWP MODES OF 2. The furnace control board activates the blower (high OPERATION speed). The blower purges refrigerant from the cabinet, plenum, and ductwork. The modes of operation for the furnace control board are Initializing, Normal, Leak Detected, and Fault. 3.
- Page 56 LGWP TEST BUTTON FUNCTIONALITY External Alarm (For applications with external alarms wired directly to the The furnace control board is equipped with a Test/Reset furnace control board) push button. The Test button can be used to perform sev- The furnace control board triggers the external alarm sys- eral functions, depending on the mode of operation of the tem when it enters Leak Detected mode.
- Page 57 VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION BLOWER SPEED CHART (ML193UH) FACTORY CONNECTED SPEED TAPS UNIT COOL HEAT PARK PARK BURNERS 030XE36BK BLACK YELLOW BROWN BLUE 045XE36BK BLACK YELLOW BROWN BLUE 070XE36BK BLACK BLUE BROWN YELLOW FLAME ROLLOUT FLAME FLAME ROLLOUT IGNITER 090XE36CK BROWN...
- Page 58 IX - Troubleshooting HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER DELAY OFF. CONTROL SELF-CHECK OKAY? (RESET CONTROL BY TURNING MAIN POWER OFF.) SEVEN SEGEMENT LED FLASHES E111 IS POLARITY CORRECT? - POLARITY REVERSED.
- Page 59 HEATING SEQUENCE CONTINUED 15 SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. SEVEN SEGEMENT LED E110 LOW LINE VOLTAGE. ONCE VOLTAGE IS ABOVE IGNITOR WARM UP -- 20 SECONDS. IS VOLTAGE ABOVE 70 VOLTS? 75 VOLTS, HEATING SEQUENCE RESTARTS. 4 SECOND TRIAL FOR IGNITION.
- Page 60 COOLING SEQUENCE OF OPERATION POWER ON IGNITION CONTROL MAIN POWER ON. GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF WITH NORMAL DELAY. CONTROL SELF DIAGNOSTIC CHECK. SIGNAL CIRCUIT BOARD FAILURE AT LED. IS CONTROL OPERATING NORMALLY? INTERRUPT MAIN POWER TO RESET CONTROL. SEVEN SEGEMENT LED FLASHES E117 IMPROPER GROUND IS THERE A PROPER GROUND? CONTROL WILL CONTINUE TO CALL FOR COOLING...
- Page 61 CONTINUOUS FAN SEQUENCE OF OPERATION MANUAL FAN SELECTION MADE AT THERMOSTAT. CONTROL (G) ENERGIZES SYSTEM FAN AT FAN SPEED. EAC TERMINAL IS ENERGIZED. THERMOSTAT CALLS FOR HEAT (W). SYSTEM FAN CONTINUES FAN SPEED WITHOUT THERMOSTAT CALLS FOR COOLING. INTERRUPTION. EAC TERMINAL REMAIN ON. HUM TERMINAL IS ENERGIZED WITH COMBUSTION SYSTEM FAN SWITCHED TO COOL SPEED.
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