false - Motor Coach Industries

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Welcome to the MCILEARN Series 

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Today’s Topic: 

A/C Troubleshooting: Micromax Systems 

If you do not have an audio connection, please dial 866-339-6642 and enter *8173541434*. The stars must be entered. 

© 2011 Motor Coach Industries, Inc. All Rights Reserved.

Agenda 

• Micromax Controller & Micromate Console Installations 

• Diagnostics & Testing of Micromax System using 

Micromate Console 

• Troubleshooting Electrical Faults 


Micromax Controller & Micromate Console 

Installations 


Micromax Controller Operation 

Computer / Processor Controlled 

• System Refrigerant; R-134a 

• Operates at full rated capacity for PULL DOWN mode, 

system capacity regulated by Compressor Unloaders 

depending upon system suction pressure 

• Coach heating system is used to modulate 

temperature of interior according to dash Micromate 

set point 

• Fresh air is induced as required by the ram air system 

• Fan speeds are automatically controlled, with 

adjustable manual override 


Micromate Control Panels 

16-10-6120 4 Button 

16-10-1056 8 Button 

16-10-6020 10 Button 

ss > 16-10-1875 

Remote diagnostic cable p/n 07-12-1699 


E/J Coaches 62780 > 64455 

16-01-6045 

Relay Module 

Logic Module 

16-10-1077 

Curbside #3 Baggage Bay Rear Bulkhead 


E J Coaches > 64455 

16-01-6045 

Relay Module 

Logic Module 

16-10-1077 

Curbside #3 Baggage Bay Overhead Compartment 

Faults, Parameters, 

Tests Decal 


D Coach > 56492 

16-01-6045 

Relay Module 

Logic Module 

16-10-1077 

Rear Bulkhead #3 Baggage Bay Compartment 


16-01-6045 Relay Module 

Fuses (device 

protection) LED ‘on’ 

means fuse is open 

Power Terminals 

Coach Interface 

Connector (JA) 

Boost 

Pump 

(JB) 

FAD LSV HV 

Drv 

LSV 

BP 

Unld 

#1 

Unld 

#2 

CL 

LSV 

High 

CF 

CF 

Logic Board 

Interface 

Connector (JC) 

High 

EVAP 

EVAP 

LED’s 

(active relay output) 

Model 

Number 


16-10-1077 Logic Module 

Manual Controls 

Input (J3) 

Configuration 

Jumpers 

Interlock 

Inputs (J4) 

Sensor 

Inputs (J6) 

Power LED, flashing once per second 

–OK Steady on- fault stored 

Code LED, Blinks 

out alarms. 

PC Interface 

Micromate 

Interface 

Connector (J2) 

Logic Power 

Connector (J1) 

Relay Board Interface (J5) 


Logic Module Configuration Jumpers 

• All Logic Modules shipped for 

use in MCI D Coach 

• D Coach configuration; 

A-B-C-F-H-J-M-O 

• J Coach configuration; 

A-B-C-F-J-M-N-O 

• ‘H’ jumper changes H/P Safety 

Cut-out setting, ‘L’ jumper is 

for programming purposes 

• ‘L’ jumper must be removed 

before coach is placed into 

service 


Micromax ‘Auto’ Mode 


Quiz 1 


Answers to Quiz 1 

1) The use of un-suppressed relays is recommended on the 

Relay Module 

FALSE 

2) The D Coach requires the ‘H’ configuration jumper to be 

installed on the Logic Module 

TRUE 

3) The Relay Module receives power from the coach 

Multiplex system 

FALSE 

4) The relay LEDs indicate when a relay is at rest (open) 

FALSE 

© 2011 Motor Coach Industries, Inc. All Rights Reserved. 

14

Micromax System 

Sensors, Inputs, & Outputs 


Micromax System Inputs 

• Micromate Console 

• Pressure transducers 

– Mounted on A/C compressor 

• Ambient temperature sensors 

– Mounted in / near condenser modules 

• Return air temperature sensors 

– Located in coach return air ducts 


Input Examples 


Micromax System Outputs 

• Compressor clutch 

• Condenser motor solenoids 

• Evaporator motor solenoids 

• Main & driver liquid solenoid valves 

• Coolant modulator valves 

• Coolant booster pump 

• Fresh air (RAM air) actuators 


Output Examples 


Diagnosis & Troubleshooting 


Typical J4500 Dash Console 


Basic Diagnostics 

1. Crank engine 

2. After initial self-test, unit 

will display set-point or 

active faults if present 

3. Pressing Up & Down 

arrows together for 3-5 

seconds will enter 

diagnostic mode 

4. Screen will display active 

or stored faults as twodigit 

codes 

A = Active I = Inactive 

5. Time stamps are available 

by pressing Auto key while 

fault is displayed 


Clearing Inactive Faults 

1. Use Up arrow to 

advance to end of fault 

list 

2. ‘-- -- --’ indicates end 

of fault list 

3. Press & hold Auto key 

until ‘Clr’ is displayed 

4. Active faults must be 

repaired and placed 

in-active before they 

can be cleared! 


System Parameters for Diagnostics 

Use Up arrow to access 

system parameters in 

read-only mode. “P” 

indicates parameter menu 

Most useful parameters: 

1. Return air 

temperature 

3. Ambient air 

temperature 

5. Suction pressure 

6. Discharge pressure 

20. Compressor hours in thousands “0,000” 2 = 2,000 hrs 

21. Compressor hours in hundreds, tens & ones “000” 

22. Evaporator motor hours in thousands “0,000” 2 = 2,000 hrs 

23. Evaporator motor hours in hundreds, tens & ones “000” 

29. Voltage received by the Relay Module from the coach 


Accessing ‘Test Mode’ for System Outputs 

Press & hold the Recirc / 

Fresh air button in the 

center for 3-5 seconds 

All components will turn 

off and “t00” will display 

10 button display – press 

‘Cool’ button 5 times in 5 

seconds to access Test 

Mode 

Test Mode has 12 separate tests that can be performed to determine if 

the coach and the Micromax Controller are capable of operating various 

system outputs 

Use the Up & Down arrow buttons to navigate the tests. If you do not 

select any tests for approximately 20 seconds, the system will default 

to the last set-point and operating mode 


Test Mode using 07-12-1699 Cable 

Cable is used to connect a spare 

Micromate Controller to the J2 

Use of a spare Micromate 

Controller and the 07-12-1699 

cable allows technicians to 

observe the Relay Module operate 

Certain fuse status LEDs such as 

the Coolant Booster Pump and 

Fresh Air actuator will only 

function when the outputs are 

‘forced’ in Test Mode 


Quiz 2 



1) Micromax and ML2-i fault codes are the same 

FALSE 

2) The four (4) button Micromate Console is a full function 

diagnostic device 

FALSE 

3) The use of the 07-12-1699 Cable allows connection of a 

Micromate Console directly to the Logic Module for 

diagnostic purposes 

TRUE 

4) Only inactive codes can be cleared from the memory of 

the Logic Module 

TRUE 


28

Testing of Input Sensors and Transducers 


Where to Test Sensors First? 

Connector J6 

Logic Module 


J6 Connector Detail 


Pressure Transducers Operation 

5 Volts 

SIGNAL 

RETURN 

GROUND 

B = 4.5 – 5.5 VDC 

5.0 VDC Nominal 

Refer to MCI Maintenance 

Manual, Section #16 or use 

table on following slide 

- or calculate- 

“C”VDC = 0.0098 X PSIG 

0.4659 


Pressure Transducer Values 


Temperature Sensor Check (Thermo-couples) 

• An accurate 

ohmmeter must 

be used to check 

resistance values 

shown in the 

table to the 

right. 

Temperature Sensor (AT, TSC, TSD & TSR) 

Resistance 

Temperature 

F 

C 

-20 -28.9 165,300 

-10 -23.3 117,800 

0 -17.8 58,500 

10 -12.2 62,400 

20 -6.7 46,300 

30 -1.1 34,500 

32 0 32,700 

40 4.4 26,200 

50 10.0 19,900 

60 15.6 15,300 

70 21.1 11,900 

77 25 10,000 

80 26.7 9,300 

90 32.2 7,300 

100 37.8 5,800 

110 43.3 4,700 

120 48.9 3,800 

Resistance in Ohms 


Quiz 3 



1) Transducers must be tested in an active, functioning 

circuit . 

TRUE 

2) Thermocouples are tested using the V-dc scale on a 

DVOM. 

FALSE 

3) When testing transducers, the voltmeter need only read 

to the tenth (0.0) of a volt. 

FALSE 

4) Suction and discharge transducers for the compressor are 

interchangeable for diagnostic purposes. 

TRUE 


36

Reference Materials Available 

• http://www.transportaircon.carrier.com 

– Online manuals 

– Online bulletins 

• T329 Rev -, 68G5-105 Series MCI J4500 Coach With 

Micromax 

• 62-03213 Rev J, Service Tool Catalog 

• Tools 

– Diagnostic cable, p/n 07-12-1699 


Questions and Answers 

Press the * on your phone to ask your question 


Thank you for your business

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