Mitsubishi Electric PURY-80TMU Service Handbook page 92

Checking code Meaning, detecting method
1505 Suction 1. Judging that the state when the
pressure suction pressure reaches 0MPa
abnormality during compressor operation
indicates high pressure by the
discharge temperature and low
pressure saturation tempera-
ture, the back-up control by gas
bypassing will be conducted.
2500 Leakage (water) When drain sensor detects flood-
abnormality ing during drain pump OFF.
2502 Drain pump When indirect heater of drain sen-
abnormality sor is turned on, rise in tempera-
ture is 20 (36) deg. or less (in wa-
ter) for 40 seconds, compared with
the temperature detected before
turning on the indirect heater.
2503 Drain sensor Short/open is detected during drain
abnormality pump operations. (Not detected
when drain pump is not operating.)
Short : 90˚C (194˚F) or more detected
Open : -40˚C (-40˚F) or less detected
Operation of When float switch operates (point
float switch of contact : OFF), error stop is ob-
served with code No. "2503" dis-
played.
Note : °C Scale (°F Scale)
Cause
• Operation while neglecting to open
ball valve. Especially for the ball
valve at low pressure side.
At cooling : Gas side ball valve
At heating : Liquid side ball valve
• When plural systems are existing,
the low pressure abruptly drop at
indoor stopping by the erroneous
wiring of transmission line (differ-
ent connection of transmission line
and refrigerant piping).
• Temporary vacuum condition due
to refrigerant distribution unbalance
(insufficient refrigerant of low pres-
sure line) immediately after charg-
ing refrigerant.
1) Water leak due to humidifier or the
like in trouble.
1) Drain sensor sinks in water be-
cause drain water level rises due
to drain water lifting-up mechanism
trouble.
2) Broken wire of indirect heater of
drain sensor.
3) Detecting circuit (circuit board)
trouble.
1) Thermistor trouble.
2) Poor contact of connector.
(insufficient insertion)
3) Full-broken of half-broken ther-
mistor wire.
4) Indoor unit circuit board (detecting
circuit) trouble.
1) Drain up input trouble.
2) Poor contact of float switch circuit.
3) Float switch trouble.
–91–
Checking method & Countermeasure
Once vacuum operation protection is
commenced, do not attempt to
restart until taking the measures
below.
<Checking method>
• Check ball valve for neglecting to
open.
• Check extended piping for
clogging when ball valve is
opened.
• Check transmission line for errone-
ous wiring. (Confirm the correct wir-
ing and piping connection between
indoor and outdoor units by oper-
ating indoor unit one by one.)
<Countermeasure>
• After checking with the above
method, make error reset by
power source reset.
• Then operate for 10~15-minutes
under the operation mode reverse
to that when the vacuum opera-
tion protection occurred (Heating
if error occurred in cooling, while
cooling if it occurred in heating),
and then enter into the ordinary
operation state.
Check water leaking of humidifier
and clogging of drain pan.
Check operations of drain pump.
Measure resistance of indirect heater
of drain sensor.
(Normal: Approx. 82Ω between 1-3 of
CN50)
Indoor board trouble if no other
problems is detected.
Check resistance of thermistor.
0˚C (32˚F) : 15kΩ
10˚C (50˚F) : 9.7kΩ
20˚C (68˚F) : 6.4kΩ
30˚C (86˚F) : 4.3kΩ
Check contact of connector.
Indoor port trouble if no other
problem is detected.
Check drain pump operations.
Check connect contact.
Check float switch operations.