Carrier WEATHERMASTER III 38HQ - Manual (Page 11)

defrost thermostat contacts will open to terminate
defrosting before 10 minutes have elapsed. The
defrost thermostat contacts open at 80 (± 6) F liquid
refrigerant temperature. When defrosting is ter­
minated, the outdoor fan motor is energized and the
reversing valve solenoid is de-energized returning
unit to heating cycle.
If the defrost thermostat contacts are open, (no
need for defrost cycle), system operates for another
90-minute interval before attempting another
defrost cycle.
Table 7 — Service Data
SYSTEM
Indoor Compr Section 38HQ227 38HQ234
Outdoor Coil Section 38HQ940 38HQ960
Fan Propeller, Direct Drive
Cfm 3100 3600
Rpm 1015 1080
Diam (in.) 20 20
Motor Hp 1/5 1/4
Factory Charge (lbs, R-22) 7 1 100
Total Req'd Charge (lbs, R-22) 9 2 11 0
Additional Charge Req'd (lbs) 2 1 1 0
SERVICE
Heat Pump Circuits shown in Fig. 9 are refrigerant
flow diagrams for heating and cooling cycles.
Refrigerant Charging — Each indoor compressor
section is shipped with a vapor holding charge; out­
door coil section contains partial system charge
as shown in Table 7. Add refrigerant to system so
that total required charge is attained as described
below. Refer to Carrier Standard Service Techniques
Manual, Chapter 1, Refrigerants for additional
information.
Adjust system charge for refrigerant line lengths
and diameters that differ from 25 ft and 3 / 8-in. O.D.
(liquid line), respectively, using refrigerant weights
shown in table below. (Twenty-five feet of 3/8-in.
O.D. tubing contains 14.4 oz of R-22.) Add R-22
charge to system if liquid line is over 25 ft; remove
charge if liquid line is shorter than 25 feet.
LIQUID LINE OUNCES OF R-22/FT LENGTH
DIAM (in.) OF LIQUID LINE
3/8 58
5/16 36
1/4 21
When recharging is necessary during heating or
cooling season, weigh in total charge indicated in
Table 7. (Charge must be weighed in during heating
season.) Remove any refrigerant remaining in sys­
tem before recharging. If system has lost complete
f.
Fig. 9 — Refrigerant Flow Diagrams
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