Mitsubishi Pury-250YMF R22 fault code 1302

[vippaker]

Hi.
Can anybody help me finding the reason for the error code 1302 appear on the Mitsubishi Pury-250YMF with R22 gas.
In the service manual code 1302 means: High pressure abnormality
I have changed the pressure sensor 63HS and high pressure switch 63H but the code still comes up and the compressor or fans won't come in. The pressure sensor 63HS reads 70psi so is not above high threshold.
I did find blown F03 2A fuse on the PCB, replaced it and it has not blown again but the unit after reset comes on again with 1302 fault code. What else besides high pressure sensor and switch can cause that fault if the compressor is not running?

[install monkey]

302
1368
1370
Liquid
side
Intermediate
side
High pressure abnoramlity (BC controller)
High pressure
abnoramlity 2
(Outdoor unit)
When press. sensor detects 1kg/
cm
2G (0.098MPa) or less just before
starting of operation, erro stop
is observed with code No.
“1302”
displayed.
When liquid side press, sensor, gas
side pressure sensor, or intermediate
pressure sensor detects
30kg/cm
2G (2.94MPa) or more, error
stop is observed with code No.
“

[vippaker]

(http://www.refrigeration-engineer.com/forums/member.php?14239-install-monkey)Hi. Install monkey
None of this apply. The fault is on the outdoor unit as the fault comes with the unit address, so i assume is not the BC controller. The pressure read by the sensor is 0.48MPa (70psi) so is below high pressure level of 2.94MPa and above low pressure level of 0.098MPa. Any ideas?

[install monkey]

have u got a service manual

(http://www.refrigeration-engineer.com/forums/member.php?14239-install-monkey)Hi. Install monkey
None of this apply. The fault is on the outdoor unit as the fault comes with the unit address, so i assume is not the BC controller. The pressure read by the sensor is 0.48MPa (70psi) so is below high pressure level of 2.94MPa and above low pressure level of 0.098MPa. Any ideas?

[stufus]

Faulty check valve on compressor discharge pipe,or duff PCB.
Cheers
Stu

[Thermatech]

YMF outdoor units have X20 relay. The coil of the relay is in the 240v 63h high pressure safety switch circuit.
F3 protects this 240v circuit.
If the compressor never tries to start it may be due to x20 open circuit due to failed coil & possible cause of the blown F3 fuse.

If the compressor does start up but trips within a few seconds with no rise in pressure suspect compressor discharge check valve failed in closed position.

To confirm allow compressor to start. watch gauge pressure or set sw1 to display HP sensor data.
with multi meter watch 240v on HP safety switch.
If no rise in system high side pressure but safety switch goes open & comp stops on 1302 then discharge check valve must have failed.
look at the refrigerant flow diagram in the service manual & you will uderstand.