Service Section 6
6-6
COMPRESSOR ELECTRICAL
DIAGNOSTICS
The compressor will not start or will trip repeatedly
on overload.
Check Resistance (Ohm) Values
NOTE: Compressor windings can have very low
ohm values. Use a properly calibrated meter.
Perform the resistance test after the compressor
cools. The compressor dome should be cool enough
to touch (below 49°C/120°F) to assure that the
overload is closed and the resistance readings will
be accurate.
1. Disconnect power from the ice machine and
remove the wires from the compressor
terminals.
2. The resistance values must be within published
guidelines for the compressor. (see chart below)
The resistance values between C and S and
between C and R, when added together, should
equal the resistance value between S and R.
3. If the overload is open, there will be a resistance
reading between S and R, and open readings
between C and S and between C and R. Allow
the compressor to cool, then check the readings
again.
Compressor Specifications
Embraco
Compressors
230/50/1 115/60/1
Model FFI-12HBK FF10HBK
Oil
Charge
350 ml
(11.8 fl. oz.)
350 ml
(11.8 fl. Oz.)
FLA (amps) 3.0 6.2
LRA (amps) 20.0 40.0
Start Winding (ohms)
29.9 5.4
Run Winding (ohms)
5.86 1.2
Check Motor Windings to Ground
Check continuity between all three terminals and
the compressor shell or copper refrigeration line.
Scrape metal surface to get good contact. If
continuity is present, the compressor windings are
grounded and the compressor must be replaced.
Determine if the Compressor is Seized
Check the amp draw while the compressor is trying
to start.
Compressor Drawing Locked Rotor
The two likely causes of this are:
• Defective starting component
• Mechanically seized compressor
To determine which you have:
1. Install high and low side gauges.
2. Try to start the compressor.
3. Watch the pressures closely.
A. If the pressures do not move, the compressor
is seized. Replace the compressor.
B. If the pressures move, the compressor is
turning slowly and is not seized. Check the
start relay.
Compressor Drawing High Amps
The continuous amperage draw on start-up should
not be near the maximum fuse size indicated on the
serial tag. The voltage when the compressor is
trying to start must be within ±10% of the
nameplate voltage.
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