heat pump Mitsubishi stop heating after some dayes working

[Hami]

I have installed 2 unit Mitsubishi hara 6,6 ,they worked in heat mode very good but almost after 3 days both of them stop heating. I checked the low pressure was 150psi
and very hot on suction line but other tiny line is not any . how is possible two separated unit should get same problem at the same time and what has gone wrong under installation?

[The Viking]

Low pressure at 150psi you say, where did you measure this? On the service port on the outside of the outdoor unit or inside the outdoor unit?

Also, what is the outside temperature like in Norway at the moment?

Unless it is well below zero where you are, my best guess sitting in front of my computer some 2000 Km away is that you either got a leak on each system and lost their refrigerant charge or that you got debris in the pipework blocking things up.
This is a situation where you really need an experienced engineer with his/her hands directly on the system.

:cool:

[Hami]

Hi Viking
Thanks for reply , actually there is only one service port I have here by outdoor unit where on suction valve I can measure pressure and that service valve is very hot.Outside temp. is between 5 to -5 , as you say it looks blocked somewhere in system ,condenser is cold and I couldn't find any leak.
for sure when I find out the problem will share with you .

[Brian_UK]

That large pipe should be hot when in heating mode as it contains hot gas.

[install monkey]

there should be a common suction port on it if its mr slim

[The Viking]

So if you had 150psi on that port then the discharge pressure is 150psi...

Now, who installed this?
Was OFN used when brazing?
Was there proper pressure testing before vaccing?
Were the systems properly vacuumed out?
How were the gas charges verified?

The way forward is to reclaim the refrigerant and weigh how much refrigerant there is in each system and compare this with what the systems should hold.

:cool: