Ill describe BOTH situations, and hopefully youll get back to me as quickly as you can….
#1) Customer calls with a complaint that their a/c unit isn’t cooling enough to reduce the space temp to the thermostat setting. It is running continuously running on the 3rd hot day. The thermostat has been set at 73 degrees, the house temp is 78 degrees. Air is coming out of the registers, so the filter must be clean. The air is cool, but not as cold as it should be. The air temp. should be about 55 degrees, and it is 63 degrees.
At the condensing unit the suction line is cool, but not cold. The liquid line seems extra cool. It is 90 degrees outside, and the condensing unit should be condensing at about 120 degrees. If the unit had 15 degrees of subcooling, the liquid line should be warmer than hand temp. yet it is not.
Gages are attached to check the suction pressure, which reads 95 psig, and the discharge pressure is 225 psig. The airflow is restricted to the condenser, and the head pressure gradually climbs to 250 psig, while the suction pressure rises to 110 psig. The compressor should have a current draw of 27 amps, but it is only drawing 15 amps. What is the likely problem and the recommended solution?
#2) Commercial customer calls to indicate the a/c unit in a small office bldg was running, but suddenly shut off. Tech arrives, goes to the space thermostat and finds that its set at 74, and the space temp is at 77. The fan is not running. The fan switch is moved to the ON position, but the fan motor does not start. It is determined that the control voltage supply is in the roof condensing unit on this particular installation. Electrical test instruments are taken to the roof, and the breakers appear to be in the ON position. The low voltage terminal block is mounted inside, is checked showing line voltage but no control voltage. What is the likely problem and the recommended solution?
These are questions out of a book for school, and I think know the answers, but want to check to see if im right? Its for extra credit and I want to get it! Thanxx again!