Problems

Possible Reasons

Truck Refrigeration Units Repair Manual                                         

      Truck
      Refrigeration
      Units
      Not
      Refrigerating

   Evaporator fans working

Condenser fan not work, compressors work                 

Check out whether the fans contact fall off or not, fans whether damage or not and ground wire whether working or not.

Both condenser fans and compressors not working
 

Check out temperature detect switch (TDS) whether damage or not, electric relay whether pull in or not,and its contact whether loose.
 

Condenser fans working, compressors not working
 

Check out clutch whether damage or not, connector lug whether fall off, belt whether loose

 

  Evaporator
fans not  working

Both condenser fans and compressors working

Check out whether speed-control switch working or not, fan lines whether break or not, and blower ground lines whether damage or not.
 

Both condenser fans and compressors not working
 

Check out whether the fuse blows out or not, and whether the electric relay working or not.
 

 Compressors working

Evaporator fans and condenser fans working

Fill too much refrigerant,check it whether meet the standard amounts with high and low pressure controller

Not using truck reefer units for a long time, and check whether it still has refrigerant or not.
 

    Truck
    Refrigeration
    Units
    Refrigerating
    Not
    Enough
 

                           Compressors    working

Evaporator fans,condenser fans working; evaporators and condensers working
 

Liquid receiver inlet and outlet connect inversely.
Check out the expansion valve whether blocked by ice or filth, and change liquid receiver.
 

Fans and other parts all working

Check whether condenser surface blocked by filth.

 Problems 

Reasons

Self-checking

At the beginning, it refrigerates well, but after a while using refrigerating effect decline; the high and low pressure data is lower.

Driving reefer trucks on the bumpy roads, because of the shocking frequently, resulting in wire contacts loose, and refrigerant leakage.

 

Using leakage meter check out where the leaking place is, screw down loose contacts and fill in refrigerant.   
 

The truck reefer unit not refrigerating; blowing hot air from blower outlet; expansion valve outlet and inlet blowing air same temperature; low presser controller shows lower number reading.
 

Using improperly.
Expansion value temperature wrap damages, valve bore closed, and resulting in refrigerant leakage.
 

Change expansion value, refill in refrigerant.

Outlet air not cooling and compressor temperature increasing; the pointer in low pressure controller downs quickly nearly to “0 “and high pressure reading more increasing.

Expansion value filter screen is blocked by mess, and it frosts in expansion value or the expansion value “sweats”.

If the blocking is not serious, start off freezing system at intervals can clear the mess.
Or take away the expansion value, use alcohol cleaning it, empty refrigerant and refill refrigerant again. 
 

 Refrigerating not enough,foresting in evaporator; both high and low pressure reading are lower. 
 

Expansion value orifice has no effect. 

Empty refrigerant, change expansion value and refill refrigerant.
 

 After few days working of the units, refrigerating is declining gradually, high pressure controller reading higher and low pressure controller reading lower.  
 

Drying agent in reservoir is saturate; expansion throttle is blocked by ice.

Empty refrigerant, change expansion value and refill refrigerant.
 

Start off the freezing system, only has air flowing but cold air, and high and low pressure controller no reading. 

TDS poor contact or compressor electromagnetic clutch wire damages.

Use the multi-meter check out the TDS whether damage or not; change the compressor electromagnetic clutch.
 

Item

Fault Code

  Diagram Display

Solutions

Inner temp. sensor

Inner temp. sensor open

circuit: P1-H
 
Inner temp. sensor

short-circuit: P1-L
 

  Refrigeration mode when set temperature
 
   is under 0℃ and vice versa.

   Fault code flashes every 1 sec.

Defrost temp. sensor

Defrost temp. sensor open

circuit：P2-H

Defrost temp. sensor

short-circuit: P2-L

Defrosting according to defrost temperature

shut down.

Fault code and inner temperature alternate

display every 1 sec.
 

Refrigerant

line pressure

High pressure fault：HP

Low pressure fault：LP

All shut down.

Fault code and inner temperature alternate

display every 1sec.
 

Power voltage

Under DC 19V / DC10V ： LUEr

Over DC 32V / DC16V： HUEr

All shut down.

Fault code and inner temperature alternate

display every 1sec.
 

Temp. abnormal alarm

High Temp Alarm: HA

Low Temp Alarm：LA

No variation in output.

Stand-by

Stand-by model cannot

detect AC power:

NOSP

  All shut down. Fault Code. If want use

ROAD OPERATION,

must restart the controller.