11
TROUBLESHOOTING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing or servicing system, always turn off, tag and
lockout main power to system. There may be more than 1
disconnect switch.
!
WARNING
CUT HAZARD
Failure to follow this caution may result in personal injury.
Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing and gloves when
handling parts.
CAUTION
!
NOTE
: Reference Table 7 Troubleshooting Chart
This can be a quick guide in resolving unit problems. It is also
recommended to review and understand Wall Control Board
Operation and Care and Maintenance sections before continuing.
There are 3 main parts to focus on when troubleshooting HRV
unit:
wall control, electronic control board and blower motor
.
Wall Control
Typically, the wall control is either good or it is bad. Use Table 1,
2, 3, or 4 to determine if wall control is operating correctly. Use
Fig. 7 to check control wire connections.
NOTE
: The electronic control board and wall control operate on
12vdc.
Control Board
Electronic control board must have wall control attached before
unit will function properly (except for units equipped with manual
switch such as the new horizontal units). Also, configuration
jumpers located on control board must match configuration setup
shown on Fig. 14 under Jumper Table. In addition, outside air
thermistor must be connected to control board for it to operate
properly. See Table 6, Temperature/Ohm Relationship, for valid
temperature range.
Blower Motor
The HRV blower motor operates on 115VAC, with 2--speed
operation.
The easiest way to check blower speed operation is to use the wall
control and initiate a low--speed blower and high--speed blower
operation.
NOTE
: If there is a short circuit or an open circuit at thermistor,
CPU will go into a 5 minute defrost cycle every 20 minutes. This
feature is not there on older board versions with 3 pin jumpers.
Table 6 – Temperature/Ohm Relationship
TEMP
〈°
F/
°
C)
OHMS
30/---1
34,480
32/0
32,630
34/1
30,760
36/2
29,220
38/4
27,470
40/5
26,020
42/6
24,680
44/7
23,320
46/8
22,070
48/9
20,910
50/10
19,830
52/11
18,820
54/12
17,870
56/14
16,920
58/15
16,160
60/16
15,260
62/17
14,530
64/18
13,790
66/19
13,090
68/20
12,480
70/21
11,860
72/22
11,270
74/24
10,750
76/25
10,250
78/26
9,750
80/27
9,300
82/28
8,840
84/29
8,432
86/30
8,042
88/31
7,668
90/32
7,310
92/33
6,993
94/34
6,661
96/35
6,368
98/36
6,085
100/38
5,811
102/39
5,571
104/40
5,313
106/41
5,088
108/42
4,869
110/43
4,660
112/44
4,450
114/46
4,268
116/47
4,019
118/48
3,918
120/49
3,750
