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Posted by on September 23, 2007, 8:02 pm
> Hi:
> I'm fairly new to the trade. I am employed by a company that owns 40+
> McDonalds.
> I am having an issue with a Bohn/Heathcraft MAC 8G unit.
> The original call was for a warm box. When I assessed the system, I
quickly
> found that the system was off on the HPCO. I reluctantly hoisted a
recovery
> unit on the roof and dropped the head pressure to about 300#. I would
have
> gone lower, but the low side pressure was only at 20# (this is a R404
> system).
Recovery unit to recover refrigerant on a working unit, why???
> All went well for about 24 hours. Then I got a call again. This time,
the
> head was at about 350# and the suction was in a slight vacuum. The sight
> glass thus far has been full and clear.
That's because you masked the real problem.
How's the condenser coil?
> I attempted to add some gas. The sight glass on my gauges was indicating
> that gas was transferring, but the head went up very slow and no matter
how
> much gas I tried to put in, the suction pressure always went below zero,
> usually very slowly.
> I checked the EEV, that was opening and closing. Checked the pressures on
> the other side of filters/driers where possible. There was no difference.
> I spoke to our lead technician. he agreed that I checked all that I could
> and it must be the control circuit board in the box. I changed that. No
> difference. Previously I had also changed all four sensors in the box as
> the room temp sensor was giving erratic readings.
> Like I said, I'm fairly new to the trade (one year). Anybody have any
ideas
> as to what I might be overlooking?
Post the full set of readings you took (before & after) messing with it.
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> I'm fairly new to the trade. I am employed by a company that owns 40+
> McDonalds.
> I am having an issue with a Bohn/Heathcraft MAC 8G unit.
> The original call was for a warm box. When I assessed the system, I