At some stage in the morning, I, Rodica and Cheryl thought that Laser room was hot. We checked the Beckhoff temperature monitors which looked fine, but it was so hot that we convinced ourselves that the monitors are bogus (later it turned out that Beckhoff monitors that are reporting temperatures were all frozen).
The touch panel interface from AirCare Automation was reporting that the A/Cs were both running, but they were clearly not running. Toggling running/stop from the touch panel didn't change the situation, it would say that A/Cs were running but they were not.
While we were trying various things, the temperature was running up quickly and the PMC started dropping lock and relocking repeatedly with a few minutes' interval because the PMC temperature servo couldn't keep up.
After a while I noticed that there are good old hardware A/C control panels from Mitsubishi in the laser room, the sensors of these panels were reporting 28 degree C instead of 20, and an error message was on the display. I switched it off and on, and after a while we felt that the temperature was coming down.
The room temperature came back to normal after a few hours, but some things (e.g. PMC) is very slow to respond, and it's still going back to where it used to. Because of this, PMC servo is dropping lock once per 10 minutes or so as of now.
I disabled the temperature servo of PMC and leave it like that for tonight.
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I wanted to see when exactly the room temperature started rising, but I couldn't because the Beckhoff monitors were all frozen from last Friday. But anyway it should have been me because I'm the only person who touched A/C.
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One thing though, I was told to turn A/C on and off from AirCare touch panel, but Livingston manual says this is done from Mitsubishi control panel. If this should NOT be done from the touchpanel, fine, but the touchpanel should not pretend as if it can control and monitor the status of A/Cs.
I looked at some monitors that are sort of related to PSL room temperature and found that the most likely failure point was NOT when I turned everything off (except the make up air) and then back on with some reduced HEPA setting in the evening on Monday, but it was when I turned everything back on with full speed in the morning.
For record, last night I temporarily turned off HEPA and A/Cs, and reduced the make up air to 30%, for a short while.
In the same evening I turned A/C back on, and left PSL laser room HEPA off, set PSL ante room HEPA to 55% level, and Make up air to 75%.
The time this happened is shown as a pink line in the attached. As you can see, after this, because of reduced HEPA and make up air, the temperature very slowly dropped but nothing drastic happened. At some point the temperature servo for PMC bottomed out (see Ch1 and Ch2) but the PMC was still locked (Ch7). At this point A/Cs were most likely running fine.
This morning at about 10AM (Cyan line), before anybody went into the PSL room I made sure that everything was back to 100%. I set both of HEPAs to "100" more than once, as I thought the touch panel was displaying 100% even though it should be displaying 55% when I first saw the setting. I also toggled A/Cs to make sure that the touch panel display responds to my request to change A/C status, and made sure to go back again so that it was reporting "running" for both A/Cs.
Apparently the system didn't like it, PMC temperature started going up rapidly, PMC dropped lock, and the refcav transmission dropped drastically (Ch.4) probably because of the alignment drift caused by the temperature change.
The change in temperature was noticed by us, and at about noon A/Cs were turned on again via Mitsubishi control panel, so we were A/C-less for two hours.
It seems like the the alignment to the refcav never came back.