MacDon M155 Operators Manual - Manual (Page 306)

MAINTENANCE AND SERVICING
3. Reattach drain hoses to drain tubes and secure with
hose clamps (A).
Figure 5.57: Red Dot HVAC System
Air Conditioning Compressor
The compressor is protected from excessively low suction and high discharge pressures by two switches that shut
down the compressor to prevent damage to the system. These switches do not require any regular servicing or
maintenance, so if problems occur and the switches are suspect, contact your MacDon Dealer.
• The low pressure switch is normally closed with an A/C charge in the system. It is located at the outlet of the
evaporator (under cab in A/C box). It will open when the pressure falls to 2–8 psi (14–55 kPa) and close when
pressure rises above 15–25 psi (103–172 kPa).
• The high pressure switch is normally closed with an A/C charge in the system and is located on the receiver drier
(right-hand frame rail, behind back of fuse panel). It opens if pressure exceeds 360–380 psi (2482–2620 kPa) on
rising pressure. It will close when pressure falls below 220–280 psi (1517–1931 kPa) on falling pressure.
If the compressor cycles rapidly due to rapid pressure changes, the cab display module (CDM) displays a warning
“CHECK A/C SYSTEM”. Contact your Dealer.
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