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Refrigeration Diagnosis Chart

Observe refrigeration system in areas listed below while engine operates at 2, 000 RPM with control lever in "HI" and temperature dial at 65. Blower motor should be disconnected when required in chart.

System Defect Outlet Air Temp. (in "HI") Sight Glass Head Pressure At Ambient Temperature Evaporator Pressure Evaporator Outlet Pipe (Ahead of STV) Oil Bleed Line System Correction
-No Defect-
Normal		 40-50° Clear Temperature 29-32 P.S.I. Cold Warm  
Bubbly with blower off 70 80 90 100 Maintains press with blower disconnected Gets cold with blower disconnected
160
200		 190
230		 220
260		 250
290
Low Charge (1) Warm Foamy or Bubbly Low Normal to Low Warm Cold Find and repair leak. Recharge
Lost Charge (1) Warm Clear Very low Very low Warm Warm Find and repair leak. Recharge
Expansion (1) valve inlet screen(2) plugged Warm Clear Low Low Warm Warm Replace X-valve
Capillary (2) broken (Valve (1) Closed). Goes to vacuum with blower disconnected Cold-Equalizer line also cold Clean or replace inlet screen
Capillary bulb-poor contact to pipe or bad insulation Normal to Warm Clear Normal High Cold to Cool Warm Reclamp bulb at 3 o'clock location. Replace insulation
Suction throttling valve-setting too high Warm Clear Normal High Cool to Warm Cold  at low Ambient temp Warm  at high Ambient temp Replace STV
Won't pull down with blower disconnected
STV-Shut due(1) to loss of (2) bellows vacuum or binds shut Warm Foamy to Bubbly Normal High Warm Warm Replace STV (Note: car with this defect will not take full charge)
Equalizer Line cold
STV-Stuck (1) Open Cold Clear Low High or Low Cold Warm Replace STV
May lose air flow on humid days Goes to vacuum with blower disconnected
Restriction in (1) receiver (Liquid line cold) Warm Bubbly Low Low Cool or Warm Cool or Warm Replace receiver dehydrator
Over charge (blows relief valve on hot days) Normal Clear High Normal Cold Warm Recharge to specification
(1) Can cause superheat switch to close and shut off compressor.
(2) Run test at least twice. Allow system to warm up and equalize before repeating. If condition doesn't recur, system has excess moisture causing ice to form in valve. Discharge, evacuate for 1/2 hour, recharge, Change dehydrator if necessary.
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