Carrier HS070-160 manual Electronic Expansion Valves

Electronic Expansion Valves

CHECKOUT PRCKEDCRE ~ 1-<11low steps below t o diagnose and correct EXV problems, For an explanarjon of EXV operation, see paye 2 1.

Step 1 - Check EXV Driver Outputs ~ Chcuk l_XV output signals at appropriate terminals on the E.YV driver module (Fig. 8) as folIows:

Connect positive test lcad to terminal 1 on EXV driver. Set meter for approximately 20 vdc. Enter outputs sub-

function of test function by pressing m ‘4 , then

advance to EXVA Open Quick Test by pressing h 5 El

times. Press ENm . The driver should drive the EXV fully iRmIl

open. During the next several seconds connect the nega- tive test lead to pins 2. 3, 4 and 5 in succession. Voltage should rise and fall at each pin. If it remains constant at a voltage or at zero volts, remove the connector to the valve

and recheck. Press to reach the EXV A Close Quick

Test. If a problem still exists, replace the EXV driv’er. If the voltage reading is correct, the expansion valve should be checked. Next, text EXVB. Connect the positive test lead to pin 7 and the negative to pin 8,9, IO, 1 l in succes- sion during the EXVB Quick Test.

Step 2 - Check EXV Wiring ~ Check wiring to elec- tronic expansion valves from terminal strip on EXV driver (Fig. 8).

1.Check color coding and wire connections. Make sure they are connected to correct terminals at driver and EXV plug connections.

12.

EXV A

Fig. 8 - EXV Cable Connections to

EXV Driver Module

2.Check for continuity and tight connection at all pin terminals.

3.Check plug connections at driver and at EXVs. He sure EXV connections are not crossed.

Step 3 ~ Check Resistance of EXV Motor Windings ~ Remove rnBug at 137 terminal strip and check resistance between c’ommon lead (red wire, terminal Uj and remain- ing leads A, B, C. and E (see Fig. 8). Resistance should be 25 ohms -t-i’-2ohms.

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