Carrier RAV-SP180UT-UL Service Manual page 56

No. Item
8 Freeze preventive control
(Low temperature release)
9 High-temp. release
control
Outline of specifications
1) The cooling operation (including Dry operation) is
performed as follows based on the detected
temperature of Tc sensor or Tcj sensor.
When [J] zone is detected for 6 minutes
(Following figure), the commanded frequency is
decreased from the real operation frequency.
After then the commanded frequency changes every
30 seconds while operation is performed in [J] zone.
In [K] zone, time counting is interrupted and the
operation is held.
When [ I ] zone is detected, the timer is cleared and
the operation returns to the normal operation.
If the commanded frequency becomes S0 because
the operation continues in [J] zone, the return
temperature A is raised from 41°F (5°C) to
53.6°F (12°C) until [ I ] zone is detected and the
indoor fan operates with [L] mode.
[˚C]
5
2
In heating operation, the freeze-preventive control
works if 4-way valve is not exchanged and the
following conditions are satisfied.
(However the temperature for J zone dashing control is
changed from 35.6°F (2°C) to 23°F (–5°C.))
<Conditions>
Q R
• When or is established 5 minutes after
activation.
Q
Tcn ≤ Tc (n – 1) – 5
R
Tcn < Tc (n – 1) – 1 and Tcn ≤ Ta < 41°F (5°C)
1) The heating operation is performed as follows based on the detected temperature
of Tc sensor or Tcj sensor.
• When [M] zone is detected, the commanded frequency is decreased from the
real operation frequency. After then the commanded frequency changes every
30 seconds while operation is performed in [M] zone.
• In [N] zone, the commanded frequency is held.
• When [L] zone is detected, the commanded frequency is returned to the original
value by approx. 6Hz every 60 seconds.
Setup at shipment
Control temp. °F (°C)
A
132.8 (56)
(129.2 (54))
NOTE:
When the operation has started or when Tc or Tcj < 86°F (30°C) at start of the
operation or after operation start, temperature is controlled between values in
parentheses of A and B.
– 56 –
I A
K
J
Tc, Tcj
˚F [˚C]
B
125.6 (52)
(125.6 (52))
Remarks
Tcj:
Indoor heat exchanger
sensor temperature
Tcn:
Tc temperature when
5 minutes elapsed
after activation
Tc (n – 1):
Tc temperature at
start time
M
A
N
B
L