Carrier 38AUZ Novation Coil Cleaning and Maintenance, Repairing Novation Condenser Tube Leaks

NOVATION™ Coil Cleaning and Maintenance —

To clean the NOVATION condenser coil, chemicals are NOT to be used; only water is approved as the cleaning solution. Only clean potable water is authorized for cleaning NOVATION condensers.

Clean the coil as follows:

1.Turn off unit power.

2.Remove screws holding rear corner posts and top cover in place. Pivot top cover up 12 to 18 in. (305 to 457 mm) and support with a rigid support. See Fig. 21.

Fig. 21 — Pivot and Support Top Cover

3.Carefully remove any foreign objects or debris attached to the coil face or trapped within the mounting frame and brackets.

4.Using a high pressure water sprayer, purge any soap or industrial cleaners from hose and/or dilution tank prior to wetting the coil.Clean condenser face by spraying the coil core steadily and uniformly from top to bottom, directing the spray straight into or toward the coil face. Do not exceed 900 psig or a 45 degree angle; nozzle must be at least 12 in. (30 cm) from the coil face. Reduce pressure and use caution to prevent damage to air centers (fins). Do not fracture the braze between air centers and refrigerant tubes. Allow water to drain from the coil core and check for refrigerant leaks prior to start−up.

5.Replace top cover and rear corner posts.

PERSONAL INJURY HAZARD

Failure to follow this caution may result in personal injury or equipment damage.

Chemical cleaning should NOT be used on the aluminum microchannel condenser. Damage to the coil may occur. Only approved cleaning is recommended.

Repairing NOVATION Condenser Tube Leaks

RCD offers service repair kit Part Number 50TJ660007 for repairing tube leaks in the NOVATION coil crosstubes. This kit includes approved braze materials (aluminum fluxcore braze rods), a heat shield, a stainless steel brush, replacement fin segments, adhesive for replacing fin segments, and instructions specific to the NOVATION aluminum coil. See EPIC for instruction sheet 99TA526379.

The repair procedure requires the use of MAPP gas and torch (must be supplied by servicer) instead of conventional oxyacetylene fuel and torch. While the flame temperature for MAPP is lower than that of oxyacetylene (and thus provides more flexibility when working on aluminum), the flame temperature is still higher than the melting temperature of aluminum, so user caution is required. Follow instructions carefully. Use the heat shield.

Replacing NOVATION Condenser Coil

The service replacement coil is preformed and is equipped with transition joints with copper stub tubes. When brazing the connection joints to the unit tubing, use a wet cloth around the aluminum tube at the transition joint. Avoid applying torch flame directly onto the aluminum tubing.

Field Refrigerant Access Ports

Field service access to refrigerant pressures is through the access ports located at the service valves (see Fig. 6). These ports are ¼-in SAE Flare couplings with Schrader check valves and service caps. Use these ports to admit nitrogen to the field tubing during brazing, to evacuate the tubing and evaporator coil, to admit initial refrigerant charge into the low-side of the system and when checking and adjusting the system refrigerant charge. When service activities are completed, ensure the service caps are in place and secure; check for leaks. If the Schrader check valve must be removed and re-installed, tighten to 2-3 in-lbs (23-34 N-cm).

Factory High-Flow Access Ports

There are two additional access ports in the system - on the suction tube between the compressor and the suction service valve and on the liquid tube near the liquid service valve (see Fig. 6). These are brass fittings with black plastic caps. The hose connection fittings are standard ¼-in SAE Male Flare couplings.

The brass fittings are two-piece High Flow valves, with a receptacle base brazed to the tubing and an integral spring- closed check valve core screwed into the base. (See Fig. 22.) This check valve is permanently assembled into this core body and cannot be serviced separately; replace the entire core body if necessary. Service tools are available from RCD that allow the replacement of the check valve core without having to recover the entire system refrigerant charge. Apply compressor refrigerant oil to the check valve core's bottom o-ring. Install the fitting body with 96 ±-10 in-lbs (1085 ±23 N-cm) of torque; do not overtighten.

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