Fault Detection and Diagnostics for Rooftop Air Conditioners

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Figure 4-16 shows one frame after 30% of the condenser area was covered by
paper (step 2 of section 4.2.3.1). The FFSW shows that some part of the condenser area
was covered by paper. FDDW indicates that there existed two faults: refrigerant low
charge with the fault severity around 0.45 and condenser fouling with the fault severity
around 0.4. Since the overall performance degradations were less than 20% at this
moment (see SPSDW and FDDRW), service was not recommended (see FDDRW).
Figure 4-16 Outputs of the FDD demonstration after introduction of condenser fouling
fault
Figure 4-17 shows one frame after the liquid line restriction fault was introduced
by closing the restriction valve until a twenty psi pressure drop was caused (step 3 of
section 4.2.3.1). The final position of the restriction valve can be seen from the FFSW
(see Figure 4-20 for the fully opening position). FDDW indicates that there existed three