Safety Precaution - Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual

2

SAFETY PRECAUTION

2-1. Always observe for safety
Before obtaining access to terminal, all supply circuit must be disconnected.
Preparation before the repair service
• Prepare the proper tools.
• Prepare the proper protectors.
• Provide adequate ventilation.
• After stopping the operation of the air conditioner, turn off the power-supply breaker.
• Discharge the condenser before the work involving the electric parts.
Precautions during the repair service
• Do not perform the work involving the electric parts with wet hands.
• Do not pour water into the electric parts.
• Do not touch the refrigerant.
• Do not touch the hot or cold areas in the refrigerating cycle.
• When the repair or the inspection of the circuit needs to be done without turning off the power, exercise great caution
not to touch the live parts.
• When opening or closing the valve below freezing temperatures, refrigerant may spurt out from the gap between the
valve stem and the valve body, resulting in injuries.
• Be careful not to expose the fusible plug to the braze torch flame or transfer heat to it. The temperature of the fusible
plug must not become 140°F (60°C) or more while working. Protect the fusible plug with a wet cloth when necessary.
(The fusible plug breaks at 158°F [70°C]).
2-2. Cautions related to new refrigerant
■ Cautions for units utilizing refrigerant R410A
Use new refrigerant pipes.
• Avoid using thin pipes.
Make sure that the inside and outside of refrigerant piping is clean and it has no contam-
inants such as sulfur, oxides, dirt, shaving particles, etc., which are hazard to refrigerant
cycle. In addition, use pipes with specified thickness.
• Contamination inside refrigerant piping can cause deterioration of refrigerant oil, etc.
Store the piping indoors, and keep both ends of the piping sealed until just before brazing.
(Leave elbow joints, etc. in their packaging.)
• If dirt, dust or moisture enters into refrigerant cycle, that can cause deterioration of refrigerant oil or malfunction of
compressor.
The refrigerant oil applied to flare and flange connections must be ester oil, ether oil or
alkylbenzene oil in a small amount.
• If large amount of mineral oil enters, that can cause deterioration of refrigerant oil, etc.
Charge refrigerant from liquid phase of refrigerant cylinder.
• If the refrigerant is charged from gas phase, composition change may occur in refrigerant and the efficiency will be
lowered.
Do not use refrigerant other than R410A.
• If other refrigerant (R22, etc.) is used, chlorine in refrigerant can cause deterioration of refrigerant oil, etc.
Use a vacuum pump with a reverse flow check valve.
• Vacuum pump oil may flow back into refrigerant cycle and that can cause deterioration of refrigerant oil, etc.
OCH800A_3