Carrier 50DF034 - Manual (Page 14)

3. Connect one meter lead to logic panel terminal T and
the other meter lead to the loose lead wire from the
sensor.
4. Meter readings depend on temperature. Discharge
sensor readings should be between 1500 and 4500
ohms. See Fig. 19.
THERMOS!AT/TRANSMITTER (Fig. 15)
1. Set meter to 20 vdc scale.
2. Check for power to thermostat. Connect negative (-)
lead to terminal 1 and positive (+) lead to terminal 2.
Meter should read 20 vdc.
3. Connect the negative (-) lead to terminal 1 and the
positive (+) lead to terminal 4.
4. Slowly move the cooling lever below room tempera­
ture to simulate a call for cooling. Meter reading
should gradually increase to about 16 vdc. (See
Fig. 20.)
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 tempera­
ture to simulate a call for heating. Meter reading
should gradually increase to about 16 vdc. (See
Fig. 20.)
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 motor terminals. Dampers
should go fully closed.
Logic Panel Economizer Signal
3.
Disconnect terminal W on logic panel.
Connect meter (2.5 vdc scale) with negative (-) lead to
R and the positive (+) lead to W.
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 discharge) above
62 F. If air is below 50 F, there will be no voltage
signal. If air is between 50 and 62 F, voltage will be
in the same proportions.
A CAUTION
When servicing unit, shut off all electrical power
to unit to avoid shock hazard or injury from rotat­
ing parts.
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
5000
4800
4600
4400
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3800
3600
3400
3200
3000
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2400
2200
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1400
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\ 3000ÍIA1 77F( 250
L
1
60 65 70 75 80 85 90 95 100
(16) (18) (21) (24) (27) (29) (32) (35) (38)
TEMPERATURE DEGREES F (DEGREES C)
Fig. 19 — Resistance Range of the
Discharge Sensor
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' ± 25 volts
Fig. 20 — Thermostat/Transmitter Output
Voltage Ramps
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
14