[Shamu406]

Can this part stop the air compressor from working (not building up pressure at all)?

I don't own a Newell, but I have had this exact same problem with our coach, so I'll venture a opinion.  The answer to your question is "Yes".

The air compressor "works" all the time, but it only compresses air when told to by the D-2.  Recommend replacing your D-2.  This will very likely restore proper air compressor function.

http://www.manualslib.com/manual/392610/...tml#manual

Thanks Chuck! I will install the new one today.
Richard said the same thing too.