Amana R-410A Service Manual download pdf (Page 57)

SERVICING

S-112 CHECKING RESTRICTED LIQUID LINE

When the system is operating, the liquid line is warm to the

touch. If the liquid line is restricted, a definite temperature

drop will be noticed at the point of restriction. In severe

cases, frost will form at the restriction and extend down the

line in the direction of the flow.

Discharge and suction pressures will be low, giving the

appearance of an undercharged unit. However, the unit will

have normal to high subcooling.

Locate the restriction, replace the restricted part, replace

drier, evacuate and recharge.

S-113 OVERCHARGE OF REFRIGERANT

An overcharge of refrigerant is normally indicated by an

excessively high head pressure.

An evaporator coil, using an expansion valve metering

device, will basically modulate and control a flooded evapo-

rator and prevent liquid return to the compressor.

An evaporator coil, using a capillary tube metering device,

could allow refrigerant to return to the compressor under

extreme overcharge conditions. Also with a capillary tube

metering device, extreme cases of insufficient indoor air can

cause icing of the indoor coil and liquid return to the

compressor, but the head pressure would be lower.

There are other causes for high head pressure which may be

found in the "Service Problem Analysis Guide."

If other causes check out normal, an overcharge or a system

containing non-condensables would be indicated.

If this system is observed:

1. Start the system.

2. Remove and capture small quantities of gas from the

suction line dill valve until the head pressure is reduced

to normal.

3. Observe the system while running a cooling performance

test. If a shortage of refrigerant is indicated, then the

system contains non-condensables.

S-114 NON-CONDENSABLES

If non-condensables are suspected, shut down the system

and allow the pressures to equalize. Wait at least 15

minutes. Compare the pressure to the temperature of the

coldest coil since this is where most of the refrigerant will be.

If the pressure indicates a higher temperature than that of the

coil temperature, non-condensables are present.

Non-condensables are removed from the system by first

removing the refrigerant charge, replacing and/or installing

liquid line drier, evacuating and recharging.

S-115 COMPRESSOR BURNOUT

When a compressor burns out, high temperature develops

causing the refrigerant, oil and motor insulation to decom-

pose forming acids and sludge.

If a compressor is suspected of being burned-out, attach a

refrigerant hose to the liquid line dill valve and properly remove

and dispose of the refrigerant.

NOTICE

Violation of EPA regulations may result in fines

or other penalties.

Now determine if a burn out has actually occurred. Confirm

by analyzing an oil sample using a Sporlan Acid Test Kit, AK-

3 or its equivalent.

Remove the compressor and obtain an oil sample from the

suction stub. If the oil is not acidic, either a burnout has not

occurred or the burnout is so mild that a complete clean-up

is not necessary.

If acid level is unacceptable, the system must be cleaned by

using the clean-up drier method.

CAUTION

Do not allow the sludge or oil to contact the skin.

Severe burns may result.

NOTE: The Flushing Method using R-11 refrigerant is no

longer approved by Amana

Heating-Cooling.

Suction Line Drier Clean-Up Method

The POE oils used with R410A refrigerant is an excellent

solvent. In the case of a burnout, the POE oils will remove any

burnout residue left in the system. If not captured by the

refrigerant filter, they will collect in the compressor or other

system components, causing a failure of the replacement

compressor and/or spread contaminants throughout the

system, damaging additional components.

Use AMANA

brand part number RF000127 suction line filter

drier kit. This drier should be installed as close to the

compressor suction fitting as possible. The filter must be

accessible and be rechecked for a pressure drop after the

system has operated for a time. It may be necessary to use

new tubing and form as required.

NOTE: At least twelve (12) inches of the suction line

immediately out of the compressor stub must be discarded

due to burned residue and contaminates.

1. Remove compressor discharge line strainer.

2. Remove the liquid line drier and expansion valve.

3 Purge all remaining components with dry nitrogen or

carbon dioxide until clean.

4. Install new components including liquid line drier.

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Amana R-410A Service Manual Page 57

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