11
Testing Bearings
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Warning - To avoid injury when testing bearings:
1. Do not wear loose clothing, jewelry, or anything around neck when working around moving parts such as
motors, belts, blower, and fans.
2. Make sure an electrical disconnect is within reach and operating correctly and freely.
3. Do not work alone.
Note: It works best to compare two similar motors operating similar loads
1. Press SET and then press
/
to select relatively high emissivity.
2. Press MODE to select MAX.
3. Enable motor and allow it to reach steady state operating temperatures.
4. Disable the motor if possible.
5. Measure the two motor bearing temperatures.
6. Compare the two motor bearing temperatures. Unequal temperatures or a high temperature can indicate
a lubrication or other bearing problem that is resulting from excess friction.
7. Repeat the sequence for the blower bearings.
Testing Belts and Sheaves
1. Press SET and then press
/
to select relatively high emissivity.
2. Press MODE to select MAX.
3. Enable the motor and allow it to reach a steady state operating temperatures.
4. Aim the thermometer at the surface to be measured.
5. Start recording temperature.
6. Slowly move the thermometer up the belt toward second sheave.
• If belt is slipping, sheave temperature will be high from friction.
• If belt is slipping, belt temperature will remain high between sheaves.
• If belt is not slipping, belt temperature will reduce between sheaves.
• If inner surfaces of sheaves are not a true “V” shape, this indicates belt slippage and will continue to
operate at elevated temperatures until sheave is replaced.
• Sheaves must be properly aligned (include “pitch & yaw”) for belt and sheaves to operate at
appropriate temperatures. A straight edge or taut string, can be used to check alignments.
• Motor sheave should operate at a temperature consistent with blower sheaves.
• If motor sheave is at a higher temperature at motor shaft than at outer circumference, belt is probably
not slipping.
• If outer circumference of sheave is at a higher temperature than sheave at motor shaft, then the belt is probably
slipping and sheaves may be misaligned.
Checking for Blockage in Air-To-Air Evaporator or Condensers
1. Remove panels to gain access to coil return bends or hairpins.
2. Press SET and then press
/
to select relatively high emissivity for copper tube.
3. Start the refrigeration system.
4. Aim the thermometer at coil turn bends/hairpins.
5. Start recording temperature.
6. Take temperature of each return bend/hairpin.
• All evaporator return bends/hairpins should be at or slightly above evaporator saturation temperature from the
pressure/temperature chart.
• All condenser return bend/hairpins should be at or slightly less than condenser saturation temperature.
• If a group of return bends/hairpins do not conform to expected temperatures, that indicates a blocked
or restricted distributor or distributor tube.
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Summary of Contents for IR-712
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