Mitsubishi Electric PUH-P8MYA Technical & Service Manual page 51

Symptom and operation when normal
7. Remote controller display is normal
and heating operation is performed
but without any capacity (does no
heat).
Cause
(1) Insufficient refrigerant.
(2) Refrigerant piping heat insulation insuf-
ficient.
t
(3) Filter clogged.
(4) Indoor unit heat exchanger clogged.
(5) Air duct short cycle.
(6) Outdoor unit bypass circuit faulty.
–49–
Symptom judgment and remedy
(1) - Since the discharge temperature rises when
there is leakage, judge by measuring the tem-
perature.
- Check piping connections, etc. for gas leak-
age.
(2) Check heat insulation.
(3) Open intake grille and check filter.
Clean filter, and remove dust and dirt.
(4) - Since the indoor piping temperature and out-
let pressure rise when the heat exchanger is
clogged, judge by measuring the outlet pres-
sure.
- Clean heat exchanger.
(5) Remove obstruction.
(6) Check refrigerant circuit operation state.