Evacuating System.

TM 10-3930-673-34

15-3. AIR CONDITIONING SYSTEM SERVICING (CONT)

d. Evacuating System.

CAUTION

Never attempt to evacuate A/C

system if system has not been

completely discharged.

(1)

Discharge A/C system (refer to task c.).

(2)

Connect manifold gage set (refer to task

a.) to service valve ports (5) and (6).

(3)

Connect vacuum pump to center hose (4)

on manifold gage set (3).

(4)

Turn vacuum pump on and open low

pressure gage valve (1) and high pressure

gage valve (2) on manifold gage set (3).

NOTE

High side gage should drop to

"zero" or below. If not, a blockage

in A/C system is indicated.

29-30 pounds of vacuum should

be sustained on low pressure

gage for at least ten minutes. If

not, a leak in A/C system is

indicated. Identify source of leak

and repair as necessary.

(5)

Evacuate unit until low pressure gage

reads 29-30 pounds vacuum.

(6)

Continue evacuation for forty-five

minutes after correct gage reading of 29-

30 pounds vacuum has been achieved.

(7)

Turn low pressure gage valve (1) and high pressure gage valve (2) on manifold gage set

(3) to closed position after evacuation is complete.

(8)

Turn off vacuum pump and disconnect center hose (4) from vacuum pump.

NOTE

Manifold gage set can remain connected if charging A/C system will follow immediately.

(9)

Disconnect manifold gage set (refer to task b.) from service valve ports (5) and (6).

15-8