Page 241 - Workshop Manual - Aumark (BJ1051)

04-97
Diagnosis-illlumination

4. Checking tri-state pressure switch

(a) Electromagnetic clutch control:
Check pressure switch operation.
• Install a manifold pressure
gauge on the line.
• Connect positive (+) of a
low pressure side high pressure side
multimeter (in ohms range) to pin
4 and its negative (-) to pin 1.
• When refrigeration system
pressure changes, check make
and break between pins as 04
shown in the figure.

(b) Cooling fan control:
Check pressure switch operation.
• Connect positive (+) of a
multimeter (in ohms range) to pin
2 and its negative (-) to pin 3.
• When refrigeration system
pressure changes, check make
and break between pins as
shown in the figure.

Are check results normal?
Yes > Go to step 5.
No > Replace pressure switch.
5. Checking sensing bulb

(a) Remove sensing bulb (refer to “Chapter 51 Heater and Air Conditioner-Evaporator,
Replacement”).
(b) Check sensing bulb resistance.
Standard values:
Use a multimeter to
Condition Specified value
connect pins
4 ℃ 1 - 2 3.967 KΩ ± 6%

25 ℃ 1 - 2 1.487 KΩ ± 4%

Are check results normal?
Yes > Go to step 6.
No > Replace sensing bulb.

Page 241