50
SERVICING
2. Check for 24 volts at the C and G terminals of the
EBTDR.
3. If no voltage present, check fan circuit from
thermostat. If 24 volts present, proceed to step 4.
4. Using a VOM, check for line voltage from the purple
wire at the transformer (terminal 3 on 240 volt units,
terminal 2 on 208 volt units) to terminal NO on the
EBTDR. Should read line voltage. If no voltage present,
check line voltage wiring in unit. If line voltage
present, proceed to step 5.
5. Using a VOM, check for line voltage from the purple
wire at the transformer (terminal 3 on 240 volt units,
terminal 2 on 208 volt units) to the COM terminal on
the EBTDR. Should read line voltage. If not as above,
replace EBTDR.
PSC equipped, single phase model coolers and heat pumps
have an isolation relay with a 240 volt holding coil in
addition to the EBTDR.
WARNING
Disconnect ALL power before servicing.
Turn power off.
Testing relay holding coil
1. Remove the leads from the holding coil terminals 1
and 3.
2. Using an ohmmeter, test across the coil terminals 1
and 3. If the coil does not test continuous, replace the
relay.
Testing relay contacts
WARNING
Disconnect ALL power before servicing.
Turn power off.
1. Using a VOM, test resistance across relay terminals 2
and 4. Should read open.
2. Turn power on.
3. Apply 240 volts to coil terminals 1 and 3.
4. Using a VOM, check for 240 volts from terminals 3
and 1 of relay. Should read 240 volts. In no voltage,
check wiring from heater kit to relay. If voltage
present, proceed to step 5.
5. Using a VOM, check for 240 volts from L1 at contactor
to terminal 4 of relay. Should read 240 volts. Next
check from L1 at contactor to terminal 2 of relay.
Should read 240 volts.
If not as above, replace relay.
On the 5 ton units with the EEM motor, a standard fan
relay is used.
1. Apply 24 volts to coil terminals 1 and 3.
2. Using a VOM, check for 24 volts from terminals 3
and 2 of relay. Should read 24 volts. If no voltage,
check low voltage wiring from transformer to relay. If
voltage present, proceed to step 5.
3. Using a VOM, check for 24 volts from terminals 3 and
4 of relay. Should read 24 volts.
If not as above, replace relay.
S-11 Checking Loss Of Charge Protector
(Heat Pump Models)
The loss of charge protector senses the pressure in the
liquid line and will open its contacts on a drop in pressure.
The low pressure control will automatically reset itself with
a rise in pressure.
The low pressure control is designed to cut-out (open) at
approximately 22 PSIG. It will automatically cut-in (close)
at approximately 50 PSIG.
Test for continuity using a VOM and if not as above,
replace the control.
Summary of Contents for DRG0361DL00001S
Page 20: ...20 SYSTEM OPERATION...
