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Turn on the blower (no heat, no cooling) and retest. If test results with the blower on are
different than results with the blower off, this may indicate air leaks in conditioned envelope
walls. The air leaks are caused by duct leaks that create a pressure differential across the
conditioned space envelope.
TESTING BEARINGS
To avoid injury when testing bearings:
- Do not wear loose clothing, jewelry, or anything around neck when working
around moving parts such as motors, belts, blower, and fans.
Warning!
- Make sure an electrical disconnect is within reach and operating correctly
and freely.
- 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 YELLOW button 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
2. Press YELLOW button 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 higher temperature than sheave at motor shaft, then
belt is probably slipping and sheaves may be misaligned.
/
to select relatively high emissivity.
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