A four door reach in freezer that is set to 0 degrees was up to 30. It was cutting off on low pressure, cycling on every couple of minutes and cutting back off in about 30 seconds when suction got back down to about 10-15 psi. This was a few hours ago in the dark on a roof, so not looking for the leak until next week. Added some 404 (told by boss not to clear sight glass, just watch my pressures). At about 155 head/32 suction I was told to cover about half of the condenser (taped cardboard to it) to get my head up to about 190-200. Head pressure went up to right about 190, freezer temp coming down nicely. I didn't ask my boss why (he knows his stuff and was on vacation talking me through it on cell), but am really curious if this is something you guys have done before. I'm going back tomorrow morning to check the temp first thing and he will be back in town to address the issues Monday, this was just a quick fix so the customer wouldn't lose product (actually so it could still be used to sell product out of). So what's the scoop on doing this?