Carrier 69NT40-511-199, 69NT40-521 manual What You Will Need, Summary of Procedure

circuits (refer to section 5). A description of the test points follows:

NOTE

Use a digital voltmeter to measure ac voltage between TP’s and ground (TP9), except for TP8.

TP2

This test point enables the user to check if the internal protector for the compressor motor (IP-CP) is open or closed (and the Auto Transformer-IP if so equipped).

TP3

This test point enables the user to check if the optional water pressure switch (WP) contact is open or closed.

TP7

This test point enables the user to check if the Controller relay (TS) contact is open or closed.

TP8

This test point enables the user to check the suction modulation valve (SMV) current (amps), it is represented by twice the dc volts between TP8 and TP9.

TP9

This test point is the chassis (unit frame) ground connection.

6.28 WATER-COOLED CONDENSER

The water-cooled condenser is of the shell and coil type with water circulating through the cupro-nickel coil. The refrigerant vapor is admitted to the shell side and is condensed on the outer surface of the coil.

Rust, scale and slime on the water-cooling surfaces inside of the coil interfere with the transfer of heat, reduce system capacity, cause higher head pressures and increase the load on the system.

By checking the leaving water temperature and the actual condensing temperature, it can be determined if the condenser coil is becoming dirty. A larger than normal difference between leaving condensing water temperature and actual condensing temperature, coupled with a small difference in temperature of entering and leaving condensing water, is an indication of a dirty condensing coil.

To find the approximate condensing temperature, with the unit running in the cooling mode, install a gauge 0 to

36.2kg/cm@ (0 to 500 psig) on the compressor discharge service valve.

Example: Discharge pressure is 10.3 kg/cm@ (146.4 psig). Referring to Table 6-6 (R-134a pressure-temperature chart), the 10.3 kg/cm@ (146.4 psig) value converts to 43_C (110_F).

If the water-cooled condenser is dirty, it may be cleaned and de-scaled by the following procedure:

a.Turn unit off and disconnect main power.

b.Disconnect water pressure switch tubing by loosening the two flare nuts. Install one-quarter inch flare cap on water-cooled condenser inlet tube (replaces tubing flare nut). De-scale tubing if necessary.

What You Will Need:

1.Oakite composition No. 22, available as a powder in 68 kg (150 lb) and 136 kg (300 lb).

2.Oakite composition No. 32, available as a liquid in cases, each containing 3.785 liters (4 U.S. gallon) bottles and also in carboys of 52.6 kg (116 lbs) net.

3.Fresh clean water.

4.Acid proof pump and containers or bottles with rubber hose.

NOTE

When Oakite compound No. 32 is being used for the first time, the local Oakite Technical Service representative should be called in for their suggestions in planning the procedure. They will show you how to do the work with a minimum dismantling of equipment: how to estimate the time and amount of compound required; how to prepare the solution; how to control and conclude the de-scaling operation by rinsing and neutralizing equipment before putting it back into service. Their knowledge of metals, types of scale, water conditions and de-scaling techniques will be highly useful to you.

Summary of Procedure:

1.Drain water from condenser tubing circuit. Clean water tubes with Oakite No. 22 to remove mud and slime.

2.Flush.

3.De-scale water tubes with Oakite No. 32 to remove scale.

4.Flush.

5.Neutralize.

6.Flush.

T-268-07 6-30