Carrier 69UG15 Servicing Low Oil Pressure Switch, Servicing Poly V-belt, 2 Low Coolant Sensor

4.Run engine 6 to 12 hours and drain system while warm. Rinse system three times after it has cooled down. Refill system with water.

CAUTION

Use only ethylene glycol, anti-freeze (with inhibitors) in system. Use of glycol by itself will damage the cooling system (Refer to paragraph 1.10.j.).

5.Run engine to operating temperature. Drain system again and fill with treated water/anti-freeze (see above Caution note).

4.4.6Servicing the Low Coolant Sensor a. Testing the Low Coolant Sensor (LCS)

1. Verify the coolant level is correct.

2. Verify the wiring to the sensor is correct.

3.Check voltage (12.5 to 13.5 VDC) to the B terminal with the ignition switch on (see Figure 4-2).

4.Check continuity between terminals A and C (see Figure 4-2) while 12 VDC is applied to terminal B.

5.Drain the coolant from the system to below the level of the coolant sensor and remove the sensor as described in Section 4.4.6.b., steps 1 and 2 below.

6.With the sensor removed from the radiator and 12 VDC applied to terminal B, the circuit between terminals A and C should be open.

4.Reconnect the harness and refill the radiator to proper level.

4.4.7 Servicing Low Oil Pressure Switch

1.Remove harness connection from low oil pressure switch (LOP).

2.Remove pressure switch from engine.

3.Apply Teflon thread sealer to threads of new low oil pressure switch.

4.Install new low oil pressure switch.

5.Reconnect harness connection to low oil pressure switch.

4.4.8Servicing Heater Switch 1. Remove control box cover.

2. Remove all connections going to heater switch (HS).

3. Remove heater switch from control box.

4. Install new heater switch.

5. Reconnect wire harness connections to switch.

6.Confirm that wires are connected to correct terminals.

7.Reinstall control box cover.

4.4.9 Servicing Poly V-belt

WARNING

Beware of moving poly V-belt and belt driven components.

Figure 4-2 Low Coolant Sensor

CAUTION

Never open the radiator cap when the coolant is hot.

b. Replacing the Low Coolant Sensor (LCS)

1.Loosen the radiator drain pet cock and drain coolant to a point below the sensor into an approved container.

2.Unplug the harness and remove sensor from radiator header.

3.Apply Teflon thread tape or thread sealer to the LCS threads and install sensor.

WARNING

Beware of pinch points.

NOTE

A frayed, cracked or worn poly V-belt must be replaced. After installing a new belt, check the adjustment after running the unit for three or four hours. This will allow for the initial stretch, which is common on new belts. Once this initial stretch has taken place, the belt should be checked at regular intervals.

The poly V-belt is driven by a sheave on the engine crankshaft. Its two functions are: (1) to drive the radiator fan and (2) to drive the water pump.

To replace the poly V-belt, perform the following steps:

1.Using the proper size socket, slowly rotate the crank on the crank pulley nut. At the same time, use a flat, blunt object to guide the belt off the crank pulley towards radiator. Be careful not to damage grooves on the pulley.

2.Replace the poly V-Belt by positioning the belt on the water pump pulley, and while rotating the engine (as in step 1), use a flat, blunt object to guide the belt onto the crank pulley. Be careful not to damage grooves on the pulley or belt.

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