General System Troubleshooting Q3 and Qht Controls for Chilled Water Systems
14 L-2962 ENGLISH
TROUBLESHOOTING
GENERAL SYSTEM TROUBLESHOOTING
Before you call for service, review this list. It may save you time and expense. This list contains common occurrences that are
not a result of defective workmanship or materials. If you need service after trying these procedures, call your nearest Dometic
dealer.
See additional troubleshooting information in the manual for your specific air conditioning system. See also “Digital-Controls
Troubleshooting” on page 15.
Table 6: General System Troubleshooting
PROBLEM POSSIBLE REASON/SOLUTION
System will not start. 1. Air handler circuit breaker is off. Turn circuit breaker on at ship’s panel.
2. Digital control is not turned on. Press the Power button.
3. Wrong wiring at terminal strip. Check wiring diagram; correct if necessary.
4. Input-line voltage is insufficient. Check power source (shore/generator) for proper
voltage. Check wiring and terminals for proper sizes and connections. Verify with a
volt-meter that the power at the unit is the same as the power source.
5. Push-on connectors or butt splices became disconnected during installation.
Disconnect power supply and open electric box, check wiring diagram, correct if
necessary.
System runs continuously. 1. Set point temperature is improperly set: too low for cooling or too high for
heating. Raise or lower set point.
2. Porthole or hatches open. Close all port holes and hatches.
3. Improper air sensor location. Check your specific control troubleshooting section.
Low airflow. 1. Airflow is blocked. Remove any obstructions in return-air stream. Clean return-air
filter and grille. Check for crushed or restricted ducting; ducting must be as straight,
smooth and taut as possible.
2. Fan speed is set to manual low. If the fan speed is set to manual low, press and
release the Fan button until the desired fan speed and airflow are reached. If you
want automatic fan speed control, press and release the Fan button until the letter “A”
displays.
Fan is not running.
Check “Digital-Controls Troubleshooting” on page 15.
No cooling or heating. 1. Temperature set point is satisfied. Lower or raise set point.
2. Fan is not running. Check your specific control troubleshooting section.
3. Control is in fan-only mode. Set system for Cool Mode or Heat Mode.
4. Digital control is programmed for Cool or Heat only. See “Digital-Controls
Troubleshooting” on page 15.
5. Chilled-water loop is inadequately cooled or heated, chiller system is not in the
proper mode of operation, or Electric Heater is disabled. Check the loop inlet
water temperature at the digital control by pressing the Up and Power buttons
simultaneously while in the On mode. If the water temperature is not at least 10°F
warmer (for heat mode) or cooler (for cool mode), the bypass valve will not open.
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