Carrier 50DL - Manual (Page 17)

reading should gradually increase to about
16 VDC. (See Fig. 23.)
5. Move the cooling lever above room temperature.
Meter reading should drop to less than 2 VDC.
6. Remove the (+) meter lead from terminal 4 and
connect it to terminal 5.
7. Slowly move the heating lever above room tem­
perature to simulate a call for heating. Meter
5000
4800
4600
4400
4200
4000
3800
3600
3400
3200
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
N L____
\
^30 OOnAT 77F( >50
'
60 65 70 75 80 85 90 95 100
(16) (18) (21) (24) (27) (29) (32) (35) (38)
TEMPERATURE DEGREES F (DEGREES C)
Fig. 22 — Resistance Range of
the Discharge Sensor
reading should gradually increase to about
16 VDC. (See Fig. 23.)
8. Move the heating lever below room temperature.
The meter reading should drop to less than
2 VDC.
ECONOMIZER (Motor Operation) — Check to
see 115 V is at the economizer motor. Remove wire
from the W terminal on damper motor. Dampers
should go fully open.
Short between R-W on motorterminals. Dampers
should go fully closed.
Logic Panel Economizer Signal
1. Disconnect terminal W on logic panel.
2. Connect meter (2.5 VDC scale) with negative (-)
lead to R and the positive (+) lead to W.
3. Set thermostat for a call for cooling. Meter
reading should rise to 1.5 VDC. If thermostat
was already calling for cooling, reading will be
1.5 V when meter is connected.
4. Turn thermostat up so that no cooling is called
for. Voltage should fall from 1.5 VDC to 0.
Conduct the above test with air temperature at
the discharge sensor (located at unit air dis­
charge) above 62 F. If air is below 50 F, there will
be no voltage signal. If air is between 50 F and
62 F, voltage will be in the same proportions.
VOLTAGES NECESSARY TO ACTIVATE LOGIC PANEL
HEAT STAGE VOLT DC COOL STAGE VOLT DC
1 4 63 1 5 00
2 5 88 2 5 88
Differential: 63 + 07 volts Tolerance: i 25 volts
Fig. 23 — Thermostat/Transmitter
Output Voltage Ramps
Cleaning — Inspect unit interior at the beginning
of each heating and cooling season and during each
season as operating conditions require. Remove unit
top panel(s) and/ or side panels as required to expose
unit interior.
EVAPORATOR COILS — Clean with a stiff
brush, vacuum cleaner or compressed air.
CONDENSER COILS — Clean with a stiff brush
or vacuum cleaner. When cleaning with compressed
air or low-pressure water or steam, guard against
damaging compressor wiring and nearby controls.
Condenser fan motor(s) is drip-proof but not
waterproof.
CONDENSER SECTION DRAIN — Check that
area under coil is clear and drains freely.
CONDENSATE DRAIN — Check and clean
annually at start of cooling season. In winter, keep
drain and trap dry or protect against freeze-up.
FILTERS — Replace filters at start of each heating
and cooling season or as often as necessary during
each season, depending on operating conditions.
Refer to Table 1 for type and size of filter used.
Filter access panels are shown in Fig. 4. Return air
filter tracks will accept 2 layers of 1-in. thick filters
if 2-in. filters are not available. Do not install bag
filters in standard filter tracks. Do not install
17