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425 Compact Excavator Troubleshooting & Repair

bobcat 425 Compact Excavator Blower Motor Does Not Operate how to do?

Possible Cause

1. Blown fuse. Inspect the fuse/wiring. Solution Replace fuse/repair wiring.

2. Broken wiring or bad connection. Check the fan motor ground and connectors. Solution Repair the wiring or connector.

3. Fan motor malfunction. Check the lead wires form the motor with a circuit tester. Solution Replace Motor.

4. Resistor malfunction. Check resistor using a circuit tester. Solution Replace Resistor.

5.  Fan motor switch malfunction. Check power into and out of the fan switch.  Solution Replace Fan Switch.

bobcat 425 Compact Excavator  Blower Motor Operates Normally, But Air Flow Is Insufficient how to do?

Possible Cause

1. Evaporator inlet obstruction. Check evaporator for plugging. Solution Remove obstruction and clean evaporator fins with air or water.

2. Air leak. Check to make sure air hoses are properly hooked to Louvers, and air ducts. Solution Repair of adjust.

3. Plugged cab filters, lugged cab filters,  Solution Clean or replace filters.

bobcat  425 Compact Excavator  Electrical System TROUBLESHOOTING

Disconnect the wire harness (Item 1) [Figure 70-10-1].

[Figure 70-10-1]

Disconnect the wire harness (Item 1) [Figure 70-10-1].

Check the wire harness (Item 1) [Figure 70-30-2]for voltage to the blower fan.

[Figure 70-30-2]

Check the wire harness (Item 1) [Figure 70-30-2]for voltage to the blower fan.

In the cab, place the blower switch in position 1. Check for voltage at the harness connector (Item 1) [Figure 70-30-2], Pin 3. (YELLOW wire # 5000). The voltage should be 12 volts.

In the cab, place the blower switch in position 2. Check for voltage at the harness connector (Item 1) [Figure 70-30-2], Pin 2. (RED wire # 1200). The voltage should be 12 volts.

In the cab, place the blower switch in position 3. Check for voltage at the harness connector (Item 1) [Figure 70-30-2], Pin 1. (ORANGE wire # 1010). The voltage should be 12 volts.

If there is no voltage at the wiring harness, check the harness for broken wires.

Figure 70-30-3

Figure 70-30-3

If there is voltage at the wiring harness, check the resistance to the blower fan at the thermostat/blower fan wiring connector (Item 1) [Figure 70-30-3].

Check the resistance between Pin 4 (BLACK wire # 2200) and Pin 3 (YELLOW wire # 5000).

Check the resistance between Pin 4 (BLACK wire # 2200) and Pin 2 (RED wire # 1200).

Check the resistance between Pin 4 (BLACK wire # 2200) and Pin 1 (ORANGE wire # 1010).

If there is no resistance value at any of these pins, replace the blower fan.

If there is resistance value at any of the pins, check the climate controls at the control panel inside the Excavator cab.

Figure 70-30-4

Figure 70-30-4

Remove the left rear console cover (Item 1) [Figure 70-30-4].

Figure 70-30-5

Figure 70-30-5

Position the console and wiring harness in the cab so the wiring harness can be checked [Figure 70-30-5].

Figure 70-30-6

Figure 70-30-6

Disconnect the wiring harness (Item 1) [Figure 70-30-6] from the blower switch.

Check the harness for voltage. The voltage should be approximately 12 volts.

If there is no voltage at the wiring harness, check the harness for broken wires.

Figure 70-30-7

Figure 70-30-7

If there is voltage at the wiring harness, check the blower switch [Figure 70-30-7]for resistance.

With the switch in the OFF position, there should be zero resistance between all terminals.

With the switch in the 1 position, there should be resistance between C terminal and the B terminal. And also between the C terminal and the L terminal frame [Figure 70-30-7].

With the switch in the 2 position, there should be resistance between C terminal and the B terminal. And also between the C terminal and the M terminal frame [Figure 70-30-7].

With the switch in the 3 position, there should be resistance between C terminal and the B terminal. And also between the C terminal and the H terminal frame [Figure 70-30-7].

If any of the above resistance tests fail, replace the blower switch.

Figure 70-30-8

Figure 70-30-8

Disconnect the wire harness (Item 1) [Figure 70-30-8] from the potentiometer.

Figure 70-30-9

Figure 70-30-9

Check the wire harness (Item 1) [Figure 70-30-9]for voltage. Between pins A and C the voltage should be approximately 12 volts.

If there is no voltage at the wiring harness, check the harness for broken wires.

Figure 70-30-10

Figure 70-30-10

If there is voltage at the wiring harness, check the potentiometer [Figure 70-30-10]for resistance.

The resistance should be 10K ohms between wire terminal A and wire terminal C frame [Figure 70-30-10].

If no resistance is found replace the potentiometer.

Figure 70-30-11

Figure 70-30-11

The white wire B, (Item 1) [Figure 70-30-11], on the potentiometer, is a resister wire.

Figure 70-30-13

Figure 70-30-13

The resistance between the wire terminal A and wire terminal B frame [Figure 70-30-13]should be approximately 49K ohms.

Check the resistance between the wire terminal C and wire terminal B frame [Figure 70-30-13]should be approximately 39K ohms.

Figure 70-30-14

Figure 70-30-14

To check the resistance of the white wire, turn the potentiometer control (Item 1) [Figure 70-30-14]to the full heater position.

Figure 70-30-15

Figure 70-30-15

Check the resistance between the wire terminal A and wire terminal B frame [Figure 70-30-15]should be approximately 39K ohms.

Check the resistance between the wire terminal C and wire terminal B frame [Figure 70-30-15]should be approximately 49K ohms.

If the resistance is not found replace the potentiometer.

Figure 70-30-16

Figure 70-30-16

Turn the fan switch (Item 1) to the High Speed position., Turn the temperature control (Item 2) [Figure 70-30-16] to the High cold position, with the key switch OFF.

Start the excavator and run at high idle, for ten minutes.

Figure 70-30-17

Figure 70-30-17

Check the temperature of the heater hoses (Item 1) [Figure 70-30-17].

If the hoses are hot, the heater valve is leaking internally, and needs to be replaced.

bobcat 425 Compact Excavator HEATER UNIT Removal And Installation

Drain the engine coolant.

Remove the operator seat and seat mount.

Figure 70-40-1

Figure 70-40-1

Remove the bolts (Item 1) [Figure 70-40-1]from the heater unit front cover.

Remove the front cover (Item 2) [Figure 70-40-1]from the unit.

Remove the floor mat and floor panel. (See FLOOR MAT AND FLOOR PANEL on Page 40-90-1.)

Figure 70-40-2

Figure 70-40-2

Disconnect the wire harness (Item 1) [Figure 70-40-2].

Remove the clamps (Item 2) [Figure 70-40-2]from the heater hoses.

Cap and plug the hoses with the proper caps and plugs.

Remove the heater hoses from the heater coil.

Remove the bolt (Item 3) [Figure 70-40-2]on the right side of the heater unit.

Remove the bolts (Item 4) [Figure 70-40-2]from the left side of the heater unit and remove the unit from the excavator.

Related Files

Related files:

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