CPS LS790B User manual

REFRIGERANT
LEAK DETECTOR
LS790B
OWNER’S MANUAL
U.S. PATENT 4,609,875, 5,264,833AND 5,371,467

GENERAL SPECIFICATIONS
The LS790B is a perfect combination of advanced micro-
processor driven circuitry and field practical features.
Developed from over 20 years of engineering experience and
sensor research, the LS790B incorporates 3 sophisticated
patented technologies to create the world's most advanced, yet
easy to use, refrigerant leak detector available today.
The quick and accurate location of a refrigerant leak is critical to
the thousands of professionals who rely on MAC for their leak
testing needs. Designed to effectively detect all CFC, HFC,
HCFC refrigerants and refrigerant blends, the LS790B remains
extremely versatile, even with today's rapid introduction of new
refrigerants. A range of ten sensitivity settings and patented
sensing circuitry virtually guarantees location of any refrigerant
leak of any size.
The portability of the LS790B allows the user access to any sus-
pected leak area, no matter how remote or restricted it may be.
An ergonomically shaped body provides a sure grip while the
18" flexible probe bends and twists its way into almost any posi-
tion. A multitude of other time saving and practical features pro-
vides the professional with the absolute feedback they need to
confidently say, “the leak is here”!
The following pages contain all of the necessary information
you will need to properly operate, maintain or leak test using the
LS790B A/C DETECTOR. Please take the time to thoroughly
read and understand the enclosed points prior to operating the
unit.
FEATURES
•Patented Microprocessor Controlled Circuitry
• Patented Ion-Pump® Sensor Enhances Sensitivity &
Reliability
•Patented Filter Eliminates False Signals Due to Moisture
• Steel Domed Tactile Feedback Keypad
• Three Individually Selectable Alarm Indicators (Audible Only/
Visual Only/or a Combination of Audible and Visual)
•10 Segment LED Leak Size Indicator
• Detects All Halogenated Refrigerants
•LOCK-OUT™Mode Eliminates Background Contamination
• 10 Selectable Sensitivity Ranges
• 40 Hour Battery Life
• Automatic Power Saver Feature Conserves Battery Life
• Low Battery Indicator
• Certified to SAE J1627 and CE Approved
ADDITIONAL PARTS INCLUDED
• Spare Ion-Pump® Sensor
•Patented Evaporator Filter Housing
• Carrying Case
• Earphone for Noisy Environments
• 4 AAAlkaline Batteries
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INSTRUMENT CONTROLS
1. ON/OFF Keys: Turns unit on or off.
2. ALARM SELECT Key: An audible alarm sounds when the unit
is initially turned on. Press the ALARM SELECT key once to
turn the visual alarm on. Press the key again for a combination
of the audible and visual alarms. Pressing the key a third time
will return the unit to its initial audible only setting.
3. SENSITIVITY Key: The LS790B offers 10 ranges of sensitivity
that may be selected depending on the type of refrigerant
you're working with and the size of the leak. The lowest sensi-
tivity range is automatically selected each time the instrument
is switched on. Depress and hold the SENSITIVITY key to
change the sensitivity range. The LED will move left to right (LO
to HI) until the key is released.
4. LOCK-OUT Key: Use this feature when faced with searching
for a leak in a highly contaminated area. This mode of opera-
tion measures and records in memory the highest concentra-
tion of refrigerant gas detected since the mode was selected or
the CLEAR button was depressed. Any concentration of gas
less than the highest recorded concentration is locked-out or
ignored, thereby eliminating the effects of background contam-
ination. A distinct two-tone alarm will sound when the probe is
in the area of the highest refrigerant concentration. This will be
the leak source.
5. CLEAR Key: This key is used to accomplish two tasks. First, it
is used to reset the memory locations stored in the micro-
processor when the unit is in the LOCK-OUT mode of opera-
tion. Secondly, it is used to re-calibrate the unit to surrounding
ambient conditions.
SAEJ1628 INSTRUCTIONS
SAE J1628 Recommended Procedure
NOTE: On automotive A/C systems, test with the engine not in
operation.
1. The air conditioning or refrigeration system should be charged
with sufficient refrigerant to have a gauge pressure of at least
340kPa/50psi when not in operation. At temperatures below
15°C/59°F, leaks may not be measurable, since this pressure
may not be reached.
1 2 3 4 5 6 7 8 9 10
LO HI
SENSITIVITY INCREASES
AS LED MOVES TO RIGHT
USE LEVELS 4-7 FOR R-134a
*Replace Batteries When 5th LED Flashes

2. Take care not to contaminate the detector probe tip if the part
being tested is contaminated. If the part is particularly dirty or
condensate (moisture) is present, it should be wiped off with a
dry shop towel or blown off with shop air. No cleaners or sol-
vents should be used, since the detector may be sensitive to
their ingredients.
3. Visually trace the entire refrigerant system and look for signs of
air conditioning lubricant leakage, damage, and corrosion on all
lines, hoses, and components. Each questionable area should
be carefully checked with the detector probe, as well as all fit-
tings, hose to line couplings, refrigerant controls, service ports
with caps in place, brazed or welded areas, and areas around
attachment points and hold-down on lines and components.
4. Always follow the refrigerant system around in a continuous
path so that no areas of potential leaks are missed. If a leak is
found, always continue to test the remainder of the system.
5. At each area checked, the probe should be moved around the
location, at a rate no more than 25 to 50 mm/second (1-2
in/second), and no more than 5 mm (1/4 in) from the surface,
completely around the position. Slower and closer movement of
the probe greatly improves the likelihood of finding a leak.
6. An apparent leak shall be verified at least once by blowing shop
air into the area of the suspected leak, if necessary and repeat-
ing the check of the area. In cases of very large leaks, blowing
out the area with shop air often helps locate the exact position
of the leak.
7. Leak testing of the evaporator core while in the air conditioning
module shall be accomplished by turning the air conditioning
blower on high for a period of 15 seconds minimum, shutting it
off, then waiting for the refrigerant to accumulate in the case for
ten minutes. Next, insert the leak detector probe into the blow-
er resistor block or condensate drain hole if no water is present,
or into the closest opening in the heating/ventilation/air condi-
tioning case to the evaporator, such as the heater duct or a vent
duct. If the detector alarms, a leak apparently has been found.
8. Following any service to the refrigerant system, and any other
service which disturbs the refrigerant system, a leak test of the
repair and of the service ports of the refrigerant system should
be done.
OPERATING TIPS
•Windy Conditions: Do not attempt to find a leak in windy areas.
Even very large leaks may be impossible to find as the escap-
ing gas is quickly dissipated into the atmosphere. If necessary,
fabricate a gas trap using aluminum foil around joints or fittings
or otherwise shield the search area from the wind.
•Recommended Sensitivity Setting: MAC recommends begin-
ning the leak test at level five or six. The best range of sensitiv-
ity is one that allows the variable output alarm and or visual indi-
cators to operate within the given 10 LED segments without full
saturation of the alarm. NOTE: The sensitivity range you have
selected is too high when the highest audible tone is continual-
ly achieved or all ten visual LEDs are constantly lit. Select a
lower sensitivity setting and try again.
•Selective Filter Housing: The presence of moisture in a leak
test area will cause corona leak detectors to false alarm. When
searching for leaks around evaporators or other areas where
high moisture content is present, housing with the patented
Selective Filter Housing. This filter will eliminate false alarms
caused by the presence of moisture.
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•Leak Verification: If a suspected leak is indicated, verify sever-
al times by moving the sensor away from the leak area, allowing
the alarm to clear and then back to the suspected leak. If the
instrument indicates a leak three consecutive times, you have
found a leak.
•When to use LOCK-OUT:Very large leaks or areas that have
been leaking for a long time can actually form a cloud of refrig-
erant around the entire leak area. This cloud of refrigerant will
tend to mask the actual leak source making it difficult to find. The
LS790B and its LOCK-OUT mode of operation was designed
specifically for this situation. Depress the LOCK-OUT key (three
short beeps confirms that you are in LOCK-OUT mode) and start
searching the leak area. As you search the leak area, the
LS790B will automatically memorize the detected refrigerant
concentration levels, systematically searching for the highest
refrigerant concentration level. A distinct two-tone alarm will
sound when the sensor is placed in the area of the highest refrig-
erant concentration detected. This will be your leak source.
NOTE: Do not be confused! It is possible to achieve this two-
tone alarm in areas besides the actual leak source. This will
occur as the LS790B locates a higher level of refrigerant con-
centration than it had previously stored in its memory. You will
know when the unit has found the actual leak source when the
two-tone alarm only sounds at one specific area.
MAINTENANCE
The LS790B A/C DETECTOR is designed to require a minimal
amount of field maintenance. Regular cleaning of the sensor hous-
ing air vents, replacement of the Ion-Pump®sensor and changing
the batteries are the only maintenance needs.
•Low Battery Condition: If the center segment of the LED dis-
play (located directly above the * symbol) illuminates when the
unit is switched on, the batteries are weak. Replace with "AA"
alkaline batteries only.
NOTE: DO NOT use rechargeable batteries.
•Changing the Ion-Pump® sensor: Eventually, the Ion-Pump®
sensor will need to be replaced. This condition is usually indi-
cated by abnormal or erratic performance when the instrument
is in the lowest sensitivity range. Install the new sensor as indi-
cated in Figure 1 (turn the unit OFF before attempting to change
the sensor). CPS®recommends that you change the Ion-Pump®
sensor at the beginning of every AC & R season and always
have a spare sensor available for replacement in the field.
•Patented Selective Housing Filter: Ensure that the sensor
housing inlet and outlet air vents are clean and free of materials
that may block the air from circulating through the Ion-Pump®
sensor. If the vents become dirty and clogged remove the hous-
ing from the probe and remove the Ion-Pump® sensor (turn the
unit OFF before removing the housing). Next, attempt to remove
any contaminants using LOW-PRESSURE shop air or by hand
ONLY. DO NOT attempt to clean this housing by any other
means. If the sensor housing remains contaminated, simply
replace it.
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Figure 1
LSXSF
SELECTIVE FILTER
HOUSING ELIMINATES
FALSE ALARM DUE TO
THE PRESENCE
OF MOISTURE
LSXS
ION-PUMP®
SENSOR
KEEP AIR VENTS
OPEN AND CLEAN
MAINTENANCE
When it comes to quality diagnostic and testing tools, CPS is the brand you can depend on.