MAHLE RTI RHS730 (Rev A) - Manual (Page 4)

Page 3
The high side red hose can be connected to the low side port of the RHS730 for charging to the low side of
vehicles with only a low side port. Follow the vehicle manufacturer’s charging procedure when charging to
the low side to avoid damaging the A/C system compressor.
HOW THE RHS730 OPERATES
The RHS730 is microprocessor controlled with a menu-driven user interface. All functions are performed by entering a few
simple key strokes and following the prompts on the display. The on-board charge cylinder is mounted on a load cell. The
weight of refrigerant in the charge cylinder is electronically displayed.
The RHS730 has a Fill Cylinder feature which allows refrigerant to be transferred directly into the charge cylinder without
going through the normal Recycle mode. This feature allows the RHS730 charge cylinder to be re-filled directly from a
cylinder of new refrigerant. The process automatically stops at approximately 20 lbs (9 kg).
The RHS730 recycles refrigerant in a true single-pass through the filters and stores the refrigerant in the charge cylinder
where it’s immediately available for use. This process automatically stops at 24 lbs (11 Kg) or when a 15 In-Hg (-0.5 Bar)
vacuum is sensed in the A/C system.
The RHS730 pauses for a minimum factory-set default of two minutes for out gassing and cold refrigerant to raise the
pressure back up to 3 psig (0.2 Bar) at which time the recycle process will start again and reset the Recycle Hold Timer.
When the pressure does not rise to reset the timer during the two minute pause, the display will indicate that the process
is complete. The Recycle Hold Timer can be changed every time a Recycle procedure is run.
Longer recycle hold times should be selected on colder days or when servicing an A/C system with a large liquid capacity.
Increasing this value may increase total time to recycle while decreasing the time may result in an incomplete recycling
of refrigerant from the A/C system.
Refer to the table below for guidelines on setting the Recycle Hold Timer. The value entered is stored in the memory of
the RHS730 and becomes the default value each time it is set.
Temperature Less than 50 0 F (10 0 C) 50 0 F (10 0 C) to 80 0 F (26.5 0 C) Greater than 80 0 F (26.5 0 C)
Recycle Hold Time 10 minutes 5 minutes 2 minutes
Non-condensable gases (air) are vented automatically during the recycle process.
The amount of refrigerant recycled is displayed at the end of the procedure. This value is added to the total amount
recycled and is stored in the memory of the RHS730.
A 7 CFM vacuum pump draws on both the high and low hoses, ensuring complete evacuation of the A/C system. The
amount of time that the vacuum pump has been programmed to run will count down on the display. The value entered is
stored in the memory of the RHS730 and becomes the default value each time it is set.
The low pressure gauge can be monitored to see a rise in A/C system pressure. When programmed to do so, the RHS730
will pause and start a count up timer indicating how long the vacuum pump has been off, thus allowing the operator to
determine if a vacuum leak is present based on increasing pressure over time. A rapid rise in pressure indicates the
presence of a large leak that should be repaired. A slow rise in pressure may simply indicate that a longer recycle hold time
or vacuum time value should have been entered.
A relatively constant vacuum reading over a long period of time (less than 2 In-Hg [0.05 Bar] rise over ten minutes) is the
most accurate way to check for vacuum leaks.
The RHS730 can also be programmed to pause to allow oil to be added to the A/C system after vacuuming and prior to
charging.
Charging is done from the on board charge cylinder. An integrated heater automatically engages whenever charging
occurs. The A/C capacity is entered on the Keypad. The value entered is stored in the memory of the RHS730 and
becomes the default value each time it is set. As refrigerant leaves the RHS730, the display will show an increasing weight
up to the programmed charge amount plus a factory-set one ounce (0.03 Kg) over charge amount necessary for
compensation of refrigerant loss in the hoses.
The over charge amount can be changed to accommodate different operating conditions. The amount of refrigerant
charged is added to the total amount charged and stored in the memory of the RHS730.