Service manual

50TD 204
S Compressor mechanical problems
S Low Refrigerant Charge
Moisture Contamination
With the major changes in refrigerants in today’s marketplace and
the use of hydroscopic oils the control of moisture and contaminates
have become more critical to safeguard against than ever before in
the history of mechanical refrigeration.
Contaminates are also the most difficult of all problems to deter-
mine. A Meg–Ohm meter “Megger” can be a valuable tool to aid in
the analysis of this problem. A Meg–Ohm reading log may be
started any time after 90 days of operation of the product. To per-
form the test, proceed as listed.
Disconnect all three (3) compressor leads, take a Meg-Ohm meter
reading from each compressor terminal to a good chassis ground.
Compare reading to chart below:
Meter
Reading
Meg-Ohm
Compressor
Condition
Maintenance Required
100 - ∞
Okay None needed.
50 to 100 Moisture present Replace drier.
20 to 50 Severe moisture &
possible contaminated
oil with acid present
Replace drier with acid
hold type. Run 24
hours, change to regu-
lar drier.
.5 to 20 System has severe
contamination
Remove compressor
oil and refrigerant
charge. Evacuate,
install liquid and suc-
tion line driers (acid
hold type). Recharge
with new oil and re-
frigerant. Run 24
hours. Discharge sys-
tem, discard suction
line drier, replace the
liquid line drier. Evac-
uate and recharge.
(Continued on page 51).