F3Dn Service Manual Refrigeration / Section 4.5
For Technical Support, Call 800-537-2653. Copyright
2005 Franke, Inc. All rights reserved.
4.5 Check System [Refrigerant] Pressure
and
Electronic Leak Detection
1)
Roll F3Dn unit out to disconnect power at outlet. [Pull
plug.]
2)
Using a medium Phillips screwdriver, remove two screws
securing control panel and the four screws on the sloped
access panel. [Older units]: Remove wire-form top grate.
3)
Using a standard manifold refrigeration gauge, confirm
the following pressures for units with
16 oz. [454 gm]
R404A charge:
Ø
Discharge Valve: 230 +/- 10 psig [16
±
1 Bar]
@
80
˚
F/27
°
C ambient
Ø
Suction Valve: 5 +/- 2 psig [.4
±
.1 Bar]
@
80
˚
F/27
°
C ambient
4)
If Discharge Valve pressure is HIGH and Suction Valve
pressure is LOW, check for a kinked or restricted line.
5)
If a kinked or restricted line is found,
see Section 4.7
for
Expansion Valve/Filter replacement.
6)
If Discharge Valve Pressure is LOW and Suction
Pressure is LOW, verify leak and location with an
Electronic Leak Detector. [If existing system pressures
are high enough, a thorough scan with a standard leak
detector may be sufficient to locate the exact location.]
7)
If system pressure is too low or leak[s] is intermittent and
difficult to detect, pressurize the system with Nitrogen to
an equalized MAXIMUM of 150 PSIG [10.5 Bar].
8)
Use electronic leak detector or application of a soap
solution to locate any and all leaks.
9)
IMPORTANT
: Make sure the condensing unit is off when
checking for leaks. Air movement from the fan would
inhibit the ability of the leak detector to sense refrigerant.
10) If a leak is found, see Section 4.6 for Leak Repair
Procedures.
[Photo 1]
Remover two control panel
screws and four screws on the
sloped panel, to access
compressor compartment.
[Photo 2]
Check Discharge and Suction
Valve pressures using a
manifold refrigeration gauge.
[Photo 3]
If system pressure is too low or
the leaks difficult to pinpoint,
pressurize system with 150
PSIG [10.5 Bar] of Nitrogen and
use an electronic leak detector
or soap solution.
Rev. 2 12/06
Ø
NOTE
: Do not use an electronic leak detector to locate
leaks inside the freezer evaporator housing. The foam
insulation used inside the evaporator housing contains
HFCs, which will generate false readings. Call Franke
Service if you suspect a leak in this area.
