Matt,

Does your pump ever cycle in the down position?  What is the pressure reading immediately after a normal gear extension?  1200 psi is quite high for the down side.  While not the root cause of your problem, this pressure is high enough to trigger the high side pressure switch.  I am curious how much of this pressure is caused by pressure switch and relief valve settings and how much by thermal influence.  With the plane on the ground it is normal to see low side circuit will go up and down in pressure with changes in ambient temperature.  The high side should remain at or near zero though.

Chris

 

 

Chris Zavatson

N91CZ

360 std