Ontario lockout of 2 ton geo, sight glass question

Hi everyone.
I have a 2 ton closed loop geo, the goes into lock out mode

in the last few days the ton as been locking out leaving only the aux heat running.
the manual say a the led blinking once means high pressure or lock out.

I have changes the air filter. to make sure that was not it, but the other one was not that dirty...

one thing I have noticed is the sight glass it is labeled, caution (purple), wet (orange), dry (blue).
it seem to me the the "flow" stops while the compressor is running. so much that I cant tell if its dry.

I had a technician in yesterday, he could not understand why the unit was locking out.

Current outside temp: -7C, wind chill -11C


please see my signature for info on the whole system... let me know if I should add more details...



Thank you

 

Many things, need more info.

EWT and Flow needs to be checked, then the antifreeze level.

Lack of antifreeze can stop the flow due to the coil freezing, which will cause a high pressure lockout.

 

High pressure arising from a water coil freeze-up in heating mode...doesn't a cold coil reduces low side pressure?

 

Meant to say FP1, not high pressure.

 

It's all in the manual here-
http://www.nordicghp.com/wp-content...0MAN-06-ISSUE-02-R-Series-Two-Stage-R410a.pdf

High Pressure faults in heating are most commonly caused by inadequate or no airflow.
1-Check airflow and fan operation
2-Check for faulty HP switch
3-Check control board for HP circuit operation
4-Only if NOT 1 through 3- Check refrigeration circuit for overcharge, blockage or stuck txv