16
Air Dryers—A-4400 Series Technical Bulletin
3. Slide the old lamp forward out of its cutout and discard; a pliers may
be required.
4. Splice the replacement bulb to the existing leads using wire nuts (field
furnished).
5. Slide the replacement lamp (A-4300-602 ordered separately) into the
cutout and push in until it reaches the chrome stop.
6. Reconnect the power supply to the air dryer.
7. Check that the lamp is illuminated when the compressor is running.
Note: Due to the extremely small refrigerant charge in these units
(as noted on the unit nameplate), the service valve should only be
used when evacuating and recharging the unit. When removing
charging equipment from the service valve, care must be taken to
avoid releasing any amount of refrigerant. The integral evaporator
pressure gauge (with its gauge correction) on each unit should be
used for all service procedures.
The A-4400 is factory set to follow the Evaporator Pressure vs. Ambient
Temperature curve illustrated in Figure 5. If at no load, the evaporator
pressure rises above the acceptable operating zone, one or more of the
following conditions may exist.
•
The ambient temperature or the air flow may be above the specified
limits.
•
The expansion valve may be out of adjustment or stuck in the open
position.
•
The condenser may be dirty.
•
The condenser fan motor may be inoperative.
•
The compressor may be inoperative.
If the evaporator pressure is below the acceptable operating zone
(refer to Figure 5) then either the expansion valve is out of adjustment
or the refrigerant charge is low.
If it is necessary to readjust the expansion valve, proceed as follows:
1. Switch the service bypass valve in order to bypass the dryer. Allow
the unit to run unloaded a minimum of 10 minutes prior to adjusting
the expansion valve.
2. Remove the cover from the dryer.
Refrigeration
Service
