Data Aire DAPA-2.5 Installation, Operation & Maintenance Manual page 77

Superheat and Suction Pressure Trouble Shooting Guide
Low Suction Pressure and High Superheat
1. Moisture, dirt, wax
2. Undersized TXV
3. High superheat adjustment
4. Gas charge condensation
5. Dead thermostatic element charge
6. Wrong thermostatic charge
7. Evaporator pressure drop - no
external equalizer
8. External equalizer location
9. Restricted or capped external
equalizer
10. Low refrigerant charge
11. Liquid line vapor
a. Vertical lift
b. High friction loss
c. Long or small line
d. Plugged drier or strainer
12. Low pressure-drop across the valve
a. Same as #11 above
b. Undersized distributor nozzle or
circuits
c. Low condensing temperature
Low Suction Pressure - Low Superheat
1. Low load
a. Not enough air
b. Dirty air filters
c. Coil icing
2. Poor air distribution
3. Poor refrigerant distribution
4. Improper compressor-evaporator balance
5. Evaporator oil logged
6. Flow from one TXV affecting another's bulb
*
NOTE: Data Aire has ensured that TXVs are sized properly as the unit ships from the
factory.
*
77
High Suction Pressure - Low Superheat
1. Oversized TXV
2. TXV seat leak
3. Low superheat adjustment
4. TXV Bulb installation
a. Poor thermal contact
b. Warm location
5. Wrong thermostatic charge
6. Bad compressor - low capacity
7. Moisture, dirt, wax
8. Incorrectly located external equalizer
*