Permanently installed temperature sensor arrays expand the sensors available in the standard Quick Test array as shown in the following table. The sensors are bundled into four groups coming out of the Service Assistant connector as shown. Sensors in each group go to similar positions inside the air conditioner.

1. Extra sensors for more diagnostic information.
   • Evaporator temperature difference (ETD), difference between RA and SA temperatures, is more direct indication of units capacity to cool air.
   • Condenser temperature difference (CTD), difference between AOC and AMB temperatures, is useful for distinguishing between high side heat transfer and non-condensables diagnoses.
   • Discharge temperature (DT) useful for diagnosing heat pumps in heating mode.
2. Install once and leave with unit. Saves time installing and removing for every use.
3. Reduces sensor installation errors. Get it right the first time with a trained installer.
4. Address line access and identification problems once and never again.
   • Sometimes it's difficult to identify the appropriate refrigerant lines for LT1 and LT2.
   • Sometimes accessing liquid lines in package units requires removing inconvenient panels or reaching deep into the unit over the compressor.
   • On larger units, access to the outdoor ambient requires wire lengths longer than the Quick Test array's 6 inch lead length.
5. RA and SA sensors can be adapted to inlet and outlet water temperature sensors, respectively for water cooled units.

1. Wire tie Service Assistant connector onto stage 1 suction line leaving 1.5 to 2 feet of wire to access the Service Assistant.
2. Use Velcro strap to tie connector to the stage 1 suction line for storage between tests.
3. Install ST1, LT1, and DT1 near stage 1 compressor.
   • Install onto pipe sensor with 2 UV resistant (black) wire ties. Strain relieve the sensor wire with a third wire tie about 3-4 inches from the sensor.
   • Insulate pipe mount sensors.
     • Two-inch wide self-adhesive insulation tape commonly available at HVAC supply stores is recommended.
     • Apply tension to hold sensor tightly to pipe.
     • Wrap 1-2 inches before and after probe.
     • Put two layers on top of probe.
4. If applicable, install ST2, LT2, and DT2 near stage 2 compressor in the same way.
5. Install AMB sensor to measure the outdoor ambient temperature.
   • Consider installation in shade under economizer outdoor air intake hood or outside in front of condenser coil.
   • Installation in moving air stream from ventilation outside air intake or condenser air inlet is preferred.
   • Avoid direct sunlight.
   • If installing on indoor side of unit, route wires with RA and SA sensors (see step 7 below).
6. Install AOC to measure the warm air discharged from the condenser coil.
   • Consider installing on condenser fan #1 (always on when unit is on) mounting bracket or on protective grill between fan blades and outside of the unit.
7. Run the INDOOR sensors bundle (RA and SA sensors) to the indoor section near the evaporator.
   • Consider following existing wires inside the unit.
   • This may require lifting panels or drilling access holes in the unit.
8. Install RA to measure the air temperature entering the evaporator.
   • Consider installation in filter frame.
   • If unit has an economizer, this is the mixed air temperature.
9. Install SA sensor to measure the air temperature exiting the evaporator coil.
   • Consider installation on evaporator fan mounting bracket.
10. Perform initial unit performance test.