Discovered that the Kobelco compressor (Corner Station purge air supply) had shut down due to high oil temperature -> Restarted and adjusted the throttle valve which supplies cooling water to the oil heat exchanger -> Purge air was OK during removal and reinstallation of HAM1 East Door.  Must have shut down after the West door was removed but before it was reinstalled as exiting air was noticed when the West door separated but purge air pressure absent when the West door was rehung.