AirComm Corporation Cessna 414 421 Air Conditioning System Service Manual R134a

TR-134 
Revision J 
  
 
  
September 13, 2013 
Page 24   
 
 CONDITION  
SERVICE PRESSURE 
GAUGE READING  
 PROBABLE CAUSE  
CORRECTIVE ACTION 
FAULTY 
COMPRESSOR 
 
Insufficient cooling. SUCTION  
PRESSURE:  much 
above normal 
 
 
DISCHARGE 
PRESSURE: much  
below normal Internal problem in 
compressor, or damaged 
gasket and valve. 1. Discharge system. 
2. Remove and 
check 
compressor. 
3. Repair or 
replace 
compressor. 
4. Check oil level. 
5. Replace receiver drier. 
6. Evacuate and 
charge...

TR-134 
Revision J 
  
 
  
September 13, 2013 
Page 25   
5.4 Compressor Troubleshooting 
 
A. General 
 
The following procedures are used for troubleshooting the compressor. 
 
B. Tools and Equipment 
 
 
Designation  
Ref. No.  
Qty  
Remarks 
 
 
Service Pressure Gauge  
Comm. Avail.  
1  
None 
 
DC Power Supply  
  
A/R  
None 
 
C. Compressor Troubleshooting Procedures 
 
With the air conditioning system operating, do any of the following conditions 
occur: 
 
NOTE:  Always attach a service gauge...

TR-134 
Revision J 
  
 
  
September 13, 2013 
Page 26  4. Rough running.  Internal compressor 
problem. 
 Replace compressor. 
 
6.0 CHECKS 
 
6.1 General 
 
The following procedures are used to perform typical maintenance checks for air 
conditioning system refrigerant leaks, refrigerant charge and compressor oil 
level. 
 
CAUTION:  Do not operate air conditioning system with condenser air outlet 
blocked. 
 
A. Tools and Equipment 
 
 
Designation  
Ref. No.  
Qty  
Remarks 
 
 
Service Pressure...

TR-134 
Revision J 
  
 
  
September 13, 2013 
Page 27   
6.3  Refrigerant System Leakage Check 
 
A.  The system leakage check is to be performed in an area with an ambient 
temperature of 65F or above. 
B.  Install service pressure gage to low and high pressure R-134a service 
valves. 
C.  Check for system pressure of approximately 64 psig or above.  The low 
pressure gage may be used to check system pressure.  If system 
pressure is below 64 psig, a small amount of refrigerant R-134a may be 
added...

TR-134 
Revision J 
  
 
  
September 13, 2013 
Page A-1   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
APPENDIX A 
  

TR-134 
Revision J 
  
 
  
September 13, 2013 
Page A-2   
A-1.0 CHARGE PRESSURES 
 
A-1.1 Normal Range 
 
OAT
65 25 35 135 155
70 35 40 145 160
75 35 45 150 170
80 40 50 175 210
85 45 55 225 250
90 45 55 250 270
95 50 55 275 300
100 50 55 315 325
105 50 55 330 335
110 50 55 340 345Normal range for pressuresSuction (psig) Discharge (psig)
 
Table A.1 
 
A-1.2 Interpreting Readings 
 
Suction Discharge
Low Low
Low Hi gh
Hi gh Low
Hi gh Hi ghNeeds service.  Possible 
faulty compre ssor.
Overcharged....