Ambient Temperature | Cold Coil |
|
|
10_ F | 6.45 ohms |
|
|
40_ F | 6.90 ohms |
|
|
70_ F | 7.40 ohms |
|
|
100_ F | 7.90 ohms |
|
|
b. Replacing the Coil
Remove locking nut and remove coil after disconnecting wiring. When replacing nut, torque to a value of 0.41 mkg (3
c. To Replace Valve
4.Plug in the connector for the modulation valve.
NOTE
A cold coil is a coil which has not been operating and is assumed to be at ambient temperature. Hot coils, taken after the unit has been operating in deep modulation for a long period of time, may give higher resistance readings.
1. | Pump down the unit per section 6.3. |
2. | Remove two bolts from suction service valve. |
3. | Melt solder at modulating valve connection and |
| rotate valve and tubing enough to clear compressor. |
| Remove valve and tubing. Replace defective |
| suction modulation valve, being careful to wrap |
| body of replacement valve with a wet cloth while |
| brazing (inert gas brazing procedures MUST be |
| used only). The coil need not be removed. |
12 | 9 |
| |
10 |
|
11 |
|
1. Coil Nut
1 
2 
3 
4 
5 
6 
7 
8 
4. | Install new suction service valve gasket and install |
| bolts in suction service valve. Torque to a value of |
| 2.77 to 4.15 mkg (20 to 30 ft/lb). |
5. | Solder all connections and leak check same. |
6. | Dehydrate and evacuate the unit per section 6.5. |
| Add refrigerant charge per section 6.6. |
6.26 THERMOSTATIC EXPANSION VALVE
The thermal expansion valve is an automatic device which maintains constant superheat of the refrigerant gas leaving the evaporator, regardless of suction pressure. The valve functions are: (a) automatic response of refrigerant flow to match the evaporator load and (b) prevention of liquid refrigerant entering the compressor. Unless the valve is defective, it seldom requires any maintenance other than minor periodic maintenance as follows:
1.Make sure that the excess capillary tube is secured to the power head assembly and wrapped with “Presstite.”
2.Make sure that the thermal bulb is tightly secured to the suction line and wrapped with “Presstite.”
2. Coil Nut
3. Coil Housing
4. Solenoid Coil Sleeve
5. Solenoid Coil
6. Enclosing Tube Assy.
7. Piston
8. Top Return Spring
9. Valve Body
10. Bottom Return Spring
11. Filter
12. Schrader Valve
Figure 6-28. Suction Modulation Valve (SMV)
T-268-07
a. Removing Expansion Valve (See Figure 6-29)
1.Pump down the unit per section 6.3.
2.Remove insulation (Presstite) from expansion valve bulb and power assembly and then remove thermal bulb from the suction line.
3.Loosen flare nut and disconnect equalizing line from expansion valve.
4.Remove capscrews and lift off power assembly and remove cage assembly. Check for foreign material in valve body.
