SRL Service Manual
Revision 00
July 2007
Page 45 of 56
10.2.8 High Dewpoint (Warning)
Cause: Temperature sensor B1 (dewpoint temperature) is registering a temperature above
the High Dewpoint Warning Setting (parameter A6: Default 15
o
C [59
o
F]) for more
than 3 minutes.
Result: Cuts power to the alarm contacts. Turns on Warning Light & alternates between
“Hd” and the dewpoint reading on the digital display.
Possible Causes & Remedies:
1) High ambient temperature in the compressor room due to:
a. Warm weather,
b. Poor compressor room ventilation,
c. Poorly located dryer (restricted air flow through the condenser),
d. Compressor aftercooler is exhausting warm air near the dryer.
Remedy - increase ventilation to the compressor room, duct the compressor after-
cooler out of the room, or move the dryer to a cooler location.
2) Excessive thermal load on the dryer due to excessive air flow rate and/or air inlet
temperature. (Can be confirmed using the instructions in Section 13.)
Remedy – Improve the efficiency of the aftercooler on the compressor, install an
additional or larger air or water cooled aftercooler upstream the dryer, or install a larger
dryer. If the overload is limited to a very short period of time, this alarm can be
avoided by partially opening the air by pass line to reduce the load to the dryer. Please
note that this will significantly increase the downstream dew point.
3) The dewpoint temperature sensor (B1) is out of calibration, causing a high reading.
This can be confirmed by using a temperature gun to check the temperature at the
location of the dew point probe, and comparing it to what the probe is reading.
Remedy – Replace the defective component.
4) A low refrigerant charge is keeping the air from being adequately cooled.
Remedy – Check or leaks at welds, threaded connections, schrader valve caps, and
joints of the condenser and evaporator. Repair the leak, pull the system to deep
vacuum and charge the dryer with the correct amount of refrigerant as specified in the
Section 2.3.
5) Scroll compressor is rotating backwards because the phases are inverted. In this
case the compressor does not compress the refrigerant so there is no cooling of the air.
Remedy - Swap two phases on the power supply.
To Reset: Alarm will reset automatically when the dewpoint goes at least 2
o
C below the High
Dewpoint Alarm Setting (A6). Warning Light goes off, power is restored to the alarm
contacts and “Hd” disappears from the display.
Notes: This warning is on a 15 minute delay at startup to allow the dryer to get down to
operating temperature without triggering a false alarm.
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