Refrigeration and Air Conditioning Mechanic (RAC)

Date: 12/2/2022 1:13:17 PM
Module: 140201a
Version: 21
Page: 33
Comment: Figure 26 heading says "thermal electronic" it should be thermal electric.
Status: Implemented

Date: 12/2/2022 1:27:02 PM
Module: 140201a
Version: 21
Page:
Comment: Under the heading Selection and Sizing of metering devices. It says thermal electronic,... It should read thermal electric Thermal electronic shows up again on pg 46 it should be thermal electric.
Status: Implemented

Date: 12/2/2022 1:34:03 PM
Module: 140201a
Version: 21
Page: 11
Comment: On pg 11 figure 3 above figure 3 it says "shows the pressure and temperature drop through a fixed orifice metering device. The heading below figure 3 says "pressure and temperature drop through a metering device" It is a figure of a fixed orifice metering device but then it also says " from a condenser or receiver". Fixed orifice metering devices are critically charged and do not have receivers.
Status: Implemented

Date: 12/14/2022 12:31:56 PM
Module: 140201b
Version: 21
Page: 13
Comment: Pg 13 under fig 4 "when the rising crankcase pressure at the valve outlet reaches the maximum compressor sst, the valve modulates closed" The sst has no relevance in the discussion. Its the rise in crankcase pressure that causes a rise in amp draw. How about this. ..when in a high load condition the rising crankcase pressure at the valve outlet causes a high amp draw. The maximum compressor crankcase pressure is determined by the RLA of the compressor. When maximum crankcase pressure is reached the valve will modulate towards closed to enforce the maximum crankcase pressure to limit the amp draw and prevent overloading the compressor.
Status: Declined

Date: 10/20/2022 5:05:07 PM
Module: 140201b
Version:
Page: 23
Comment: Fig 14 is wrong The hot gas bypass valve does not go there it runs between the discharge line and usually to a special distributor at the outlet of the txv or you could say to the inlet of the evaporator. There is no need for the check valve around the txv either.
Status: Declined

Date: 12/14/2022 12:38:16 PM
Module: 140201b
Version: 21
Page: 14
Comment: Under the heading Evaporator Pressure regulator it says the "valve maintains a minimum evaporator pressure" The word maintains is not accurate, maintains implies the valve tries to keep it at the minimum evap pressure. "It enforces a minimum evaporator pressure" It only Prevents the evaporator pressure from falling below the setpoint of the valve.
Status: Declined

Date: 10/20/2022 4:59:20 PM
Module: 140201b
Version:
Page: 23
Comment: The discharge bypass regulator or hot gas bypass valve. It does not maintain a maximum discharge pressure nor it it used for defrost. It is used for capacity control. The valve keeps the compressor from running in a low load condition. It does this by enforcing a minimum suction pressure when the load is very low. The valve opens and bypasses small amounts of discharge gas into the low side of the system when the suction pressure is low. .. To prevent running in a low load condition which means the compression ratio is high which we avoid.
Status: Implemented

Date: 12/14/2022 12:39:36 PM
Module: 140201b
Version: 21
Page: 14
Comment: Figure 5 Is a diagram of a pilot operated epr valve
Status: Implemented

Date: 12/14/2022 12:50:42 PM
Module: 140201b
Version: 21
Page: 18
Comment: Under Open on Rise of Differential control valve... last sentence " Most ORD valves are not adjustable. They have factory setpoints of 0psi to 5si." They have factory setpoints of 20-35psi and 20psi differential is the standard.
Status: Declined

Date: 12/14/2022 1:04:01 PM
Module: 140201b
Version: 21
Page: 24
Comment: image 15 evaporator capacity control using hot gas This figure is not typical of the hot gas bypass regulator valve configuration. The valve rarely has a temperature bulb and its not "temperature control"as the diagram says it sets a range of the valve. The valve is a cro responds only to a drop in evaporator pressure.
Status: Implemented

Date: 12/14/2022 1:10:22 PM
Module: 140201e
Version: 21
Page: 32
Comment: Figure 25 Simple hot gas defrost system during defrost Requires a liquid line solenoid in this diagram. Also I would hesitate to call the hot gas defrost line a bypass line.
Status: Implemented

Date: 1/1/2019 12:00:00 AM
Module: 140201h
Version: 1.1
Page: 52
Comment: The PE diagram is plotted incorrectly, h4 is not on the 155btu/lb line, which affects the self test answers. Also table 11 locations are incorrect, h2 should be entering compressor, h3 should be entering metering device, h5 should be exiting evaporator. The table on page 24 is also mislabeled.
Status: Update in Progress

Date: 12/2/2022 1:47:46 PM
Module: 140201h
Version: 21
Page: 28
Comment: under the heading Fouled iced or low load evaporator... 4th bullet pt says "slight increase in vapour superheat" it should be "decrease in vapour superheat" or possibly slight decrease if you have a txv
Status: Implemented

Date: 12/14/2022 1:13:11 PM
Module: 140202e
Version: 21
Page: 31
Comment: Fig 24 Simple Hot gas defrost system during cooling cycle Liquid line requires a liquid line solenoid
Status: Implemented

Date: 12/14/2022 1:22:17 PM
Module: 140202e
Version: 21
Page: 9
Comment: Fig 6 liquid overfeed evaporator In the diagram the label the "recirculated liquid overfeed evaporator as a flooded evaporator"
Status: Implemented

Date: 1/12/2023 4:28:47 PM
Module: 140204b
Version: 21
Page: 3
Comment: Pg 3 Second last paragraph. Quote "Once the motor reaches about 75% of its rated speed, a centrifugal switch interrupts the current to the start winding, and the motor continues running on the start winding"..... Should be "motor continues running on the run winding."
Status: Approved for Review

Date: 1/12/2023 4:40:11 PM
Module: 140204b
Version: 21
Page: 28
Comment: Self test answer Question 6... Second last sentence. Quote" The shaded pole motor uses an electrical switch to remove the start winding from the circuit" A shaded pole motor doesn't have a start winding it has a shading coil, which was just said a couple sentences earlier. It was probably meant to be " A RSIR motor uses an electrical switch to remove the start winding from the circuit" This is now a true statement.
Status: Approved for Review

Date: 12/2/2022 1:40:14 PM
Module: 140204b
Version: 21
Page: 14
Comment: under the heading potential relay It says "the potential relay is used only with CSCR motors. Not accurate... the potential relays are most commonly used with semi hermetic CSIR and CSCR motors.
Status: Implemented