Hi all, have had a big look around online over last few weeks and cant 100% find the answer to my problem I am having so hopefully someone has had similar problem and can help.

Recently I have replaced the compressor in my discovery 4 after chasing faults for some time. Rightly or wrongly I went with the Hitachi repo from ebay :/

Compressor is working fine, pumps up to pressure quickly and works on demand. However since replacing I am hearing the air exhaust valve operating a huge amount more than I did on the OEM Hitachi unit. It is letting out a loud, short phhisst approx 4 times in 10 minutes of the vehicle sitting idling. I did not want to lunch the new compressor so pulled the relay and to my surprise the exhaust valve continues to operate, this must be on a separate circuit. It did this for a week until the system is out of air. During this time the vehicle does not drop at any individual corner and bags, air connections and valve blocks do not show any leak with soapy water(I rebuilt blocks a year ago)

Assuming the exhaust valve/solenoid is the item mounted directly infront of the compressor? If so I have not touched this apart from testing for leaks. Will order a rebuild kit but just wanting confirmation I am on the right track as I have lost confidence in the suspension system after numerous fixes and thought it was time to consult some others on here.

A few questions.
a) Has anyone had this same problem and am I on track?
b) Is the exhaust valve venting pressure from the resivor or the gallery?
c) What is controlling venting, assuming it is not only pressure activated as it is still venting even with pump relay pulled and pressure in res/gallery would have been reduced hugely.

d) Slightly separately; Is there a way to reduce temp cut off for the compressor in aid of increasing life and piece of mind?

Thanks
Gaz