Mitsubishi PUHZ-P100VHA3 U9 Fault

[Slim R410a]

Hi Guys,

Briefly looked at this last week - seems to run ok on cooling. Indoor is PLA-RP100BA cassette.

Heating - gets past the preheat for about 5mins then goes off on a U9 Fault.
Seems to not be ramping up to full speed. Pipe sensor (I think this the liquid 3/8) on remote (PAR-21) gets to 39/40deg max.
I did manage the get it to run full speed but only briefly on test mode.
Checked there is definitely 240V at the mains in connection.

Before I return, are there any obvious/common things I need to check?
Service manual is showing a few connections to check.

Thanks,

[hyperion]

U9 is often associated with abnormal voltage in the inverter. Suggest you phone the Mitsubishi Helpdesk from the site and they will give advice as to which terminals to check the voltages at.

[eire1]

Got this from the app
15297

[Slim R410a]

Thanks both :)

[eire1]

No prob, if you Google the Par 21 controller is shows you where to go once you get the request code. Let us know how you get on.

[Slim R410a]

Ok guys, from Request code 55 I've got 0020 detail code.

According to the outdoor unit service manual, page 85, 0020 is PAM error.

Whats the next step to check?

(I'm doing this as a favour in my own time, so unfortunately can't just go to site and call Mitsi helpdesk)