York YMC2 A, Operation And Maintenance

JOHNSON CONTROLS

17

Form 160.78-O1 

Issue date: 05/19/2021

3

Section 3 - Maintenance

Renewal parts

For any required Renewal Parts, refer to the 

YMC

2

 Unit 

Renewal Parts Manual (Form 160.78-RP1).

Checking system for leaks

Leak testing during operation

The refrigerant side of the system is carefully pressure 

tested and evacuated at the factory.
After the system has been charged, the system should 

be carefully leak tested with a R-134a compatible leak 

detector to be sure all joints are tight.
If any leaks are indicated, they must be repaired im-

mediately. Usually, leaks can be stopped by tighten-

ing flare nuts or flange bolts. However, for any major 

repair, the refrigerant charge must be removed. See 

Handling refrigerant for dismantling and repairs

 in 

this section.

Conducting R-22 pressure test

With the R-134a charge removed and all known leaks 

repaired, the system should be charged with a small 

amount of R-22 mixed with dry nitrogen so that a ha-

lide torch or electronic leak detector can be used to de-

tect any leaks too small to be found by the soap test.

To test with R-22, complete the following steps:

1.  With no pressure in the system, charge R-22 gas 

into the system through the charging valve to a 

pressure of 2 psig (14 kPa).

2.  Build up the system pressure with dry nitrogen 

to approximately 75 psig to 100 psig (517 kPa to 

690 kPa). To be sure that the concentration of re-

frigerant has reached all parts of the system test 

for the presence of refrigerant with a leak detector 

at an appropriate service valve.

3.  Test around each joint and factory weld. It is im-

portant that this test be thoroughly and carefully 

done, spending as much time as necessary and us-

ing a good leak detector.

4.  To check for refrigerant leaks in the evaporator 

and condenser, open the vents in the evaporator 

and condenser heads and test for the presence of 

refrigerant. If no refrigerant is present, the tubes 

and tube sheets may be considered tight. If refrig-

erant is detected at the vents, remove the heads, 

locate the leak using a soap test or leak detector, 

and repair the leak.

Figure 5 - 

Evacuation of chiller

LD00949