Comprehensive 38TDB Service Manual for Efficient Operation and Maintenance

Table 6—Two-Speed Compressor (Winding Resistance at 70°F ± 20°)

WINDING	024	036–037	048	060
Start (S-C)	2.280	1.850	1.459	0.740
Run (R-C)	0.770	0.745	0.552	0.356

Compressor Control Contactors

Low and high capacity contactor coils are 24 volts. The electronic control board controls the operation of the low speed (C-L) and the high speed (C-H) contactors.

TEMPERATURE THERMISTORS

Thermistors are electronic devices which sense temperature. As the temperature increases, the resistance decreases. Thermistors are used to sense outdoor ambient and coil temperature. Refer to Fig. 13 for resistance values versus temperature.

If the outdoor ambient or coil thermistor should fail, a fault code appears at two-speed control.

IMPORTANT: Outdoor Air Thermistor Placement

Mount outdoor air thermistor underneath unit base pan lip on control box side of the unit as shown in Fig. 14. Attach to base pan

with adhesive tape. A small piece of TXV bulb insulation tape may be used.

IMPORTANT: If outdoor air thermistor is not properly placed underneath base pan, unit may see nuisance thermistor out of frame faults.

Step 13—Final Checks

IMPORTANT: Before leaving job, be sure to do the following:

1.Ensure that all wiring and tubing is secure in unit before adding panels and covers. Securely fasten all panels and covers.

2.Tighten service valve stem caps to 1/12-turn past finger tight.

3.Leave Owner’s Manual with owner. Explain system operation and periodic maintenance requirements outlined in manual.

4.Fill out Dealer Installation Checklist and place in customer file.

CARE AND MAINTENANCE

For continuing high performance and to minimize possible equip- ment failure, periodic maintenance must be performed on this equipment. Frequency of maintenance may vary depending upon geographic areas, such as coastal applications.