Electrical Test - Pressure Switches; High Pressure Switch And Circuit Test - New Holland T8010 Manual

Electrical Test – Pressure Switches
NOTE: See Electrical Schematic sections 58. 60 and 61.
Power and Ground
The controller feeds 5V from pin C (CCU1) to pin B on the high pressure switch. The switch is grounded to the
chassis.
The controller feeds 5V from pin B (CCU2) to pin B on the low pressure switch. The switch is grounded to the
grounding stud in the HVAC box.

High Pressure Switch and Circuit Test

Steps and Test Point
1. Refer to A/C Troubleshooting Foldout and follow
the conditions for performance testing. Install A/C
high and low side pressure gauges. High reading
above 400 psi ± 10 psi (2758 kPa ± 69 kPa)?
2. Shut off the tractor. Disconnect the switch from the
harness and the unit. Check that switch is closed
across pins A and B.
3. Reinstall the switch in the unit; do not reconnect
the harness. Keyswitch and A/C ON, blower
control on any speed, and temperature control on
maximum cool setting, Is 5V present at pin 1 at the
harness to the switch?
4. Keyswitch OFF. Measure resistance from pin A at
the switch to ground. Less than 1 ohm?
5. Keyswitch ON. Is 5V present at pin C at the
controller (CCU1)?
Section 50 - Climate Control - Chapter 1
Y E S - Pe r fo r m c o r r e c t i v e a c t i o n s f r o m A / C
Troubleshooting Foldout.
NO - Go to next Step.
OK - Go to next Step.
NOT OK - Replace switch.
YES - Go to next Step.
NO - Go to Step 5.
YES - Go to next Step.
NO - Locate open condition and repair between pin A
and ground.
YES - Locate open condition and repair between pin C
at the controller and pin B at the switch.
NO - Test the controller. See Standard Controller
Test in this Section.
50-1-75
Corrective Actions