Service manual

6-21
T-294-01
RRS or SRS:
Using the plug connector marked “EC” that is
connected to the Controller module. Locate the wires
markedRRSorSRS, dependingonwhichsensorneeds
to be replaced. Follow that wire to the connector and
usingthepins oftheplug,m easuretheohmsresistance.
Readings are shown in Table 6-5.
6.23.2 Replacing Sensor (STS and SRS)
To properly position a unit supply sensor, the sensor
must be fully inserted into the probe holder. This
positioningwillgivethesensortheoptimumamountof
exposure to the supply air stream, and will allow the
Controller to operate correctly. Insufficient probe
insertion into t he probe holder will result in poor
temperature control due to the lack of air flow overthe
sensor.
Itisalsonecessary to ensure that the probetip does not
contacttheevaporatorbackpanel.Thedesignminim um
clearanceof 6mm (1/4inch)should bem aintained(see
Figure 6-21).
Cap and Grommet
Assembly
Probe
Holder
Supply Sensor
Sensor
Wires
Supply
Air
Stream
Evaporator
Back Panel
6mm
(1/4 inch)
Figure 6-21. Supply Sensor Positioning
a. TurnunitpowerOFFanddisconnectpowersupply.
b. Removeandsaveanycover(ifpresent)overwiring
and probe holder.
c. Cutcable5cm(2i nches)fromshoulderofdefective
sensor and discard the defective probe only. Save
cap and grommet assembly for reuse on the
replacement probe. Do not cut the grommet.
d. Cutonewireofexistingcable41mm(1-5/8inches)
shorter than the other wire.
e. Cut one replacement sensor wire (opposite color)
back 41 mm (1-5/8 inches). (See Figure 6-22.)
Sensor
41 mm (1-5/8 inches)
6.35 mm (1/4 inch)
Figure 6-22. Sensor (RRS, RTS, SRS or STS)
f. Strip back insulation on all wiring 6.35 mm (1/4
inch).
g. Slide a large piece of heat shrink tubing over the
cable, and placethetwosmall piecesofheat shrink
tubing, one over each wire, before adding crimp
fittings as shown in Figure 6-23.
h. Slide the cap and grommet assembly, which was
saved in step (c.), onto the replacement sensor.
i. Slipcrimpfittingsoverdressedwires(keepingwire
colors together). Make sure wires are pushed into
crimp fittings as far as possible and crimp with
crimping tool.
j. Solder spliced wires with a 60% tin and 40% lead
Rosincore solder.
k. Slide heat shrink tubing over splice so t hat both
endsoftubingcoverbothendsofcrimpasshownin
Figure 6-23.
Sensor
Cable
Heat Shrink
Tubing (2)
Large Heat Shrink
Tubing (1)
Figure 6-23. Sensor and Cable Assembly (RRS,
RTS, SRS or ST S)
l. Heattubing,preferablywithaflamelessheatgun.If
not available, a propane torch will work (caution
shouldbetakennottoburntheheatshrinktubingor
wire insulation). Make sure all seams are sealed
tightly against t he wiring to prevent moisture
seepage.
m. Slide largeheat shrinktubing overboth splicesand
shrink tubing and heat as in step (l.).