•
•
•
•
•
•
•
•
•
•
•
•
•
•

Compressor and clutch mounting
Compressor clutch coil wiring and connection
Compressor drive belt and belt tensioner
A/C hoses and connections
Condenser mounting
Condenser fins (blockage by debris)
Receiver-drier mounting
Expansion valve mounting
Filter element
Fresh air module drains
Fresh air module mounting and overall condition
Electrical connections to pressure transducer and low pressure switch
Electrical connections to actuators for airflow doors (recirculate, temperature, and mode doors)
Fan speeds and mode door operation

Yes: Repair as necessary. Restore system to
operational condition and operate the A/C system to
determine if the complaint was corrected..

No: Go to step 3.

Were any issues found?

Step Action

Decision

Diagnostic Trouble Codes:
Yes: Go to FAULT CODES in IK1900207
3

Check for A/C related DTC’s:
No: Go to step 4.
Are any A/C related DTC’s found?

Step Action

Decision
Yes: Go to step 5.

4

Static Pressure:

No: Go to Air Conditioning Mechanical
Pressures Diagnostics IK1900225

NOTE: Have the engine OFF and A/C system at ambient temperature when measuring static pressure.If the
engine has been run recently, allow the vehicle to sit for a minimum of one hour to allow system pressures and
temperatures to stabilize.
1. Inspect high and low side Schrader valves for presence of dye and pooling of oil in valve.
2. Connect gauges to the A/C system and record static pressure readings.
3. Use a temperature probe to determine the ambient temperature within 1 or 2 degrees. Record the measured
temperature.
4. Locate the ambient temperature on the chart below and compare the vehicle’s static pressure to the chart
pressure.
Temp °F
40 °F
45 °F
50 °F
55 °F
60 °F
65 °F
70 °F
75 °F
80 °F
85 °F
90 °F
95 °F

Temp °C
4.4 °C
7.2 °C
10.0 °C
12.8 °C
15.6 °C
18.3 °C
21.1 °C
23.9 °C
26.6 °C
29.4 °C
32.2 °C
35.0 °C

R134A PSIG
35
40
45
51
57
64
71
78
86
95
104
113

https://evalue.internationaldelivers.com/service_kb/DocTool/ArticleViewer.aspx?ControlID... 6/1/2015

IK1900228 - 2010 and Newer Vehicle Air Conditioning Diagnostics (Start Here)

100 °F
105 °F
110 °F

37.7 °C
40.5 °C
43.3 °C

Page 4 of 5

124
134
146

Are the A/C pressures in spec?

Step Action

Decision

Compressor Engagement:
Yes: Go to step 6.
5

Start engine. Turn the A/C on. Verify compressor engagement.
No: Go to Air Conditioning Electrical Diagnostics
IK1900223
Does the compressor engage?

Step Action

Decision

Performance Test:
Check the System Performance by performing the following steps:
A. Park the vehicle so there is no solar loading and no wind.
B. Position a thermometer approximately 30 to 60 cm (12­24 inches) in front of the vehicle grille.

Yes: System is operating correctly.
Discuss concern with customer.

C. Engage the engine cooling fan (unless viscous fan drive).
D. Close the hood, being careful not to damage the equipment.
E. Insert a thermometer into the passenger side, left instrument panel vent. Do not allow the thermometer to
touch the sides of the duct. Insert a second thermometer into the lower passenger bunk vent
F. Start the engine and raise the idle speed to 1500 rpm.
G. Open windows and close both cab doors.
H. Set the mode control to: NORM A/C; Highest blower speed; Coldest cooling temperature.

No: gauge readings are out of specification: Go to
Air Conditioning Mechanical Pressures
Diagnostics IK1900225

I. Operate the system for five minutes, or until gauge readings settle.
6
J. Record the following data:
Test Point
Ambient Air Temperature
Relative Humidity
Cab Air duct Temp
Low­Side psi @ 1500 RPM
Compressor on (cut-in PSI)

Value

Compressor off (cut-out PSI)
High-Side psi @ 1500 RPM
Compressor on (cut­in PSI)
Compressor off (cut-out PSI)
Lower Passenger bunk vent temp

No: gauge readings are correct but cab vent
temperature is out of specification: Go to
Air Conditioning Control Head
Diagnostics IK1900226

K. Compare gauge readings, vent temperature, ambient temperature, and humidity to the appropriate HVAC
System Pressure Test Chart.

Does the Cab and rear HVAC operate correctly?

Step Action
7

Rear A/C Test:

Decision

Yes: rear HVAC system operates correctly

A. Start engine and raise engine speed to 1500 RPM.
B. Turn cab A/C switch to NORM
C. Turn cab blower switch to highest speed.
D. Turn cab temperature switch to coldest position.

No: Rear A/C does not function: Go to Rear Air
Conditioning Electrical and Mechanical
Diagnostics IK1900227
No:

https://evalue.internationaldelivers.com/service_kb/DocTool/ArticleViewer.aspx?ControlID... 6/1/2015

IK1900228 - 2010 and Newer Vehicle Air Conditioning Diagnostics (Start Here)

G. Use the dash SLPR­TEMP switch to vary sleeper temperature from warmest setting to the coldest
setting.
H. Use the Rear HVAC Control panel blower switch to raise and lower rear blower
speed.
I. Use the Rear HVAC Control panel TEMP switch to raise and lower the duct air Temperature.
J. Review rear duct temperature recorded in step­6

Page 5 of 5

rear control panel TEMP and FAN switches are
inoperative while SLPR­TEMP and SLPR­FAN
switches function: Go to Rear A/C Control Panel
Inoperative IK1900231
No: one or both SLPR TEMP and SLPR FAN
switches are inoperative but rear control panel
TEMP and FAN switches functions correctly: Go
to Sleeper Fan and Sleeper TEMP Switch
Inoperative IK1900232

No: Front and rear controls function correctly, but
rear A/C blows warm air: Go to Rear A/C Blows
Warm Air IK1900231
Do the dash SLPR-FAN and SLPR-TEMP switches control the rear A/C?
Do the rear control panel blower speed and temperature switches control the rear A/C?
Does the stabilized rear duct temperature from step-6 meet specifications (See appropriate 2010 HVAC
SYSTEM PRESSURE TEST CHART)?
WARRANTY INFORMATION:

Standard Repair Times: Due to the variety of vehicle confirgurations and number of components affected, reference the SRT Manual (quick links below) for repair times.
Description
A/C SYSTEM PRELIMINARY DIAGNOSIS (EXCEPT 5000, 9000 SERIES), PERFORM
A/C MECHANICAL PRESSURES DIAGNOSIS (EXCEPT 5000, 9000 SERIES), PERFORM
A/C ELECTRICAL DIAGNOSIS ( EXCEPT 5000, 9000 SERIES) , PERFORM
A/C CONTROL HEAD DIAGNOSIS
A/C REAR UNIT ELECTRICAL AND MECHANICAL DIAGNOSIS (EXCEPT 5000,9000 SERIES),
PERFORM
SRT Manual

Other Resources:
Document Number

Description

S16046

HEAT VENTILATION AIR CONDITIONING (HVAC) FOR 2010 ­ 3200 Bus, DuraStar®,
TerraStar™, TranStar®, WorkStar® Models

0000002221

HEAT VENTILATION AIR CONDITIONING (HVAC) FOR 2010 ProStar and LoneStar Models
(Formerly S16047)

IK1900207

2010 and Later ProStar and LoneStar HVAC Information

IK1900022

A/C Refrigerant and Oil Capacities

air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning
air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning air conditioning
Hide Details

Feedback Information
Viewed:

5009

Helpful:

23

Not Helpful: 4
No Feedback Found

Copyright © 2015 Navistar, Inc.

https://evalue.internationaldelivers.com/service_kb/DocTool/ArticleViewer.aspx?ControlID... 6/1/2015