Leak Checking; Micron (Vacuum) Gauge; Refrigerant Leak Checking - Carrier Transport Air Conditioning Installation Procedures Manual

9.1 INTRODUCTION
The purpose of leak checking is to verify the integrity of
the hose/fitting connections and components. A
refrigerant leak check should always be performed after
installing a new system or the system has been opened
to replace or repair a component. It is imperative that the
inspection for refrigerant leaks be conducted in a
through and meticulous manner. Even the smallest leak
can result in poor system performance and premature
compressor failure. When a leak occurs, the refrigerant
is replaced by air and moisture from outside the system.
Without a complete charge of refrigerant in the system,
insufficient oil is returned to the compressor. The
compressor will overheat and eventually fail. Following
established leak checking procedures will result in long
term performance and assure longevity of the system
components.

9.1.1 Micron (Vacuum) Gauge

Carrier Transport Air Conditioning recommends a
Micron (Vacuum) Gauge to assure that the proper
vacuum level is attained. When isolated according to
instructions the Micron Gauge will show a loss of
evacuation vacuum, making it an excellent first leak
check.
9.1.2 Nitrogen
A common method in use for leak detection, is
pressurizing the system with dry nitrogen and checking
with a soap bubble solution at suspected leak sites.
While this method will find large leaks, it is limited in
detection of the smaller leaks found with R134a.
WARNING
Do not use a nitrogen cylinder without a
pressure regulator
NOTE
If the system is to be pressurized with refriger-
ant gas it must be emphasized that only the cor-
rect refrigerant cylinder be connected to pres-
surize the system. Any other gas or vapor will
contaminate the system, which will require
additional evacuations (Refer to Figure 9-1 for
service connections).
SECTION 9

LEAK CHECKING

9.2 REFRIGERANT LEAK CHECKING

Never use air for leak testing. It has been de-
termined that pressurized, air-rich mixtures
of refrigerants and air can undergo com-
bustion when exposed to an ignition
source.
a. Charge the system with refrigerant 134a to build up
pressure between 30 to 50 psig.
b. Add sufficient nitrogen to raise system pressure
to150/200 psig. (10.21/13.61 bar).
Larger split systems may be equipped with ser-
vice valves and a liquid line solenoid. Ensure
these service valves are open and power the
liquid line service valve from an external
source.
c. The recommended procedure for finding leaks in a
system is with a R-134a electronic leak detector (CTD
Part Number 07-00295-00). Testing joints with soap-
suds is satisfactory only for locating large leaks.
d. Remove refrigerant using a refrigerant recovery sys-
tem and repair any leaks.
e. Evacuate and dehydrate the unit (Refer to Section 7).
f. Charge the unit. (Refer to Section 8).
9--1
WARNING
Note
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