Service manual

SERVICING
41
4. Install new components including liquid liner drier.
5. Install suction line drier.
6. Braze all joints, leak test, evacuate, and recharge sys-
tem.
7. Start up the unit and record the pressure drop across
the cleanup drier.
8. Continue to run the system for a minimum of twelve
(12) hours and recheck the pressure drop across the
drier. Pressure drop should not exceed 6 - 8 PSIG.
9. Continue to run the system for several days repeatedly
checking pressure drop across the suction line drier. If
the pressure drop never exceeds the 6 - 8 PSIG, the
drier must be adequate and is trapping the contami-
nants and it is permissible to leave it in the system.
10. If the pressure drop becomes greater, then it must be
replaced and steps 5 through 9 repeated until it does
not exceed 6 - 8 PSIG.
NOTICE: Regardless, the cause for burnout must be de-
termined and corrected before the new compressor is
started.
S-201 CHECKING EXTERNAL STATIC PRES-
SURE
The minimum and maximum allowable duct static pressure
is found in the specification section.
Too great of an external static pressure will result in insuf-
ficient air that can cause icing of the coil, whereas too much
air can cause poor humidity control, and condensate to be
pulled off the evaporator coil causing condensate leakage.
Too much air can cause motor overloading and in many
cases this constitutes a poorly designed system. To deter-
mine proper air movement, proceed as follows:
1. Using a draft gauge (inclined manometer) measure the
static pressure of the return duct at the inlet of the unit,
(Negative Pressure).
RETURN
SUPPLY
INCLINED
MANOMETER
TOTAL EXTERNAL STATIC
2. Measure the static pressure of the supply duct, (Posi-
tive Pressure).
3. Add the two readings together.
NOTE: Both readings may be taken simultaneously and
read directly on the manometer if so desired.
4. Consult proper table for quantity of air.
If the external static pressure exceeds the minimum or maxi-
mum allowable statics, check for closed dampers, dirty fil-
ters, undersized or poorly laid out ductwork.
S-202 ECM/ICM Motors
ECM/ICM Features
Many of the Amana high efficiency package units incorpo-
rate the GE
©
ICM or variable speed blower motors for greater
efficiency. ECM/ICM motors vary the motor RPMs to pro-
vide a set volume of air over a wide range of conditions.
ECM/ICM Control Connections
Control functions (G, Y1, Y2) May be Active at less than 1/
2 control voltage. (i.e. 12 volts). Relay contacts on control
functions must reliably switch low currents (less than 5 MA).
Some thermostats (with triac switches) and Solid State
Relays may allow enough "leakage" current to Turn on "G".
Thermostats that "steal" power thru "Y" or other functions
are not compatible.
The ECM control interface can be as simple as a direct
connection to the thermostat. For example: R to G will cause
fan to come at "fan-only" cfm. R to G to Y will cause fan to
come on at cooling speed. The ECM/ICM control requires
a common connection from the transformer (transformer
common to C1, C2 on control). In typical applications C1
and C2 will be tied together. Additional features can be uti-
lized with an interface control board (speed tap board), these
features include; 2 Cool CFMs, 2 Dehumidification CFMs,
2 Heat CFMs, emergency heat CFM, separate Fan-Only
CFM, and feed back information (CFM demand).
Testing ECM/ICM Motors
ECM/ICMs connect directly to the Line. DO NOT Insert
Contactors in Series with the ECM/ICM Motor AC line. Con-
trol is powered continuously to Insure reliable start-up. Plug
is polarized, verify and reverify correct connector orienta-
tion before applying power. DO NOT force plug into motor
and make sure power is off before inserting power connec-
tor. DO NOT apply voltage to terminals 1 or 2.