16
Table 8—Factory Set Blower Connection High or Low
Speed
Contro l
Module
Main Electrical
Harness Cable
Blower
Wire
Speed
J1-- 6 Orange Orange High
No Connection No Connection Blue + Cap Medium
J1-- 4 Red Red Low
Table 9—Modify Blower Connection High or Medium
Speed
Contro l
Module
Main Electrical
Harness Cable
Blower
Wire
Speed
J1-- 6 Orange Orange High
J1-- 4 Red Blue Medium
No Connection No Connection Red + Cap Low
Ta b l e 1 0— Te mp e r at ur e a nd Vo l t a g e
TEMP °F(°C)
Voltage DC Volts (J4)
--22 (--30) 3.5
-- 4 ( -- 2 0 ) 2.7
4 (--15) 2.3
14 (--10) 2.0
32 (0) 1.4
41 (5) 1.1
50 (10) 0.9
68 (20) 0.6
5. Defrost Cycle
Defrost cycle is controlled by a thermistor which is located
in the fresh ---air intake passage (the thermistor unit is
connected to J4 of control module (See Fig. 26 and 27).
When defrost temperature sensor detects the need for
defrost, K5 relay will close for 6 minutes while K1 and K2
remain energized.
This closes the outdoor air damper while running HRV
blower on high---speed. This process recirculates warm
indoor air through heat recovery core which melts any frost
that has formed. Water created in this process is collected
by HRV and drained away. Frequency of the defrost cycle
depends on outdoor temperature (See Table 11).
If defrost is not working properly, check for proper damper
operation. To do this, turn unit to OFF position. Damper
should close.
Safety F
eature
This new control has an added safety feature. If
microprocessor does not detect the thermistor or detects a
short circuit, unit will automatically go into a 6 minute
defrost cycle every 20 minutes.
DEFROST CHECK
1. Make sure defrost cable is properly connected into J 4.
2. Make sure thermistor assembly is correct. Measure
thermistor temperature reading with multimeter. Select
multimeter DC measurement scale 0---20v. At
connector J4 (without removing thermistor cable),
measure voltage between pins of thermistor cable.
Depending on temperature of outside air intake, values
should correspond with those in Table 9.
3. If reading is not correct (reading 0v for short circuit or
5v for open circuit), change thermistor assembly.
ADVANCED DEBUGGING
Defrost can be simulated using the following procedures:
1. Unplug unit from 115vac.
2. Disconnect thermistor assembly from J4.
3. Replug unit in 115vac and select high ---speed
exchange.
4. Defrost should start within 2 minutes after high--- speed
exchange has been initiated.
5. After test unplug unit.
6. Connect thermistor cable to J4.
7. Replug unit back in 115vac.
6. Control Module Jumpers
Jumpers on the control module give exact configuration to
HRV micro ---controller. If there is a mistake in the jumper
configuration, it can cause improper unit operation. This
control has a simplified jumper selection mode. Jumper
selection is done by the presence or absence of jumper at
specific location (See Tables 12 and 13).
WARNING: ELECTRICAL SHOCK HAZARD
Fail ure to fol lo w this warning could result in perso nal
injury or death.
Always disconnect unit from 115vac prior to making
any jumper change. If unit is not disco nnec ted,
micro---contr ol ler will never see jumper change.
Table 11—Defrost Cycle
OUTSIDE TEMPERATURE °F
STANDARD DEFROST (AS SHIPPED)
EXTENDED DEFROST
(JUMPER JU1---F REMOVED)
Above 23°F No Defrost
No Defrost
23°Fto5°F 6 Minute Defrost/32 Minute Exchange 10 Minute Defrost/30 Minute Exchange
4°F t o --- 1 7 °F 6 Minute Defrost/32 Minute Exchange
10 Minute Defrost/20 Minute Exchange
B e l o w --- 1 8 °F 6 Minute Defrost/20 Minute Exchange
10 Minute Defrost/15 Minute Exchange
Table 12—JU1 Jumper Definition
JU1A JU1B JU1C JU1D JU1E JU1F JU1G
UNIT IDENTIFICATION
Reverse Damper Operation
In=Normal
OUt=Inverse
Factory Set
Always In
Factory Set
Always In
HRV
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