Installing a thermostatic expansion
valve (TXV)
About this task:
CAUTION
Outdoor unit model numbers ending with an H have a
factory installed hard start kit which is required when a
TXV kit is installed. Outdoor unit model numbers with
no H ending do not require a hard start kit unless local
regulations dictate it..
The following are basic steps for installing a TXV kit. For
detailed instructions, refer to the Installation Manual
provided with the TXV kit.
Important: Refer to the Technical Guide or Tabular
Data Sheet for the unit to determine the correct TXV
kit to use on this product.
1. Relieve the holding charge by depressing the
Schrader valve core on the suction manifold stub
out.
2. When the holding charge is completely discharged,
loosen and remove the Schrader valve core.
3. Place a backup wrench on the distributor, and
loosen and remove the brass distributor nut. Retain
the brass nut for use on the liquid line. Keep the
PTFE washer in place and discard the sealing disk.
4. Install the TXV onto the distributor assembly with
the supplied fittings. Ensure the PTFE washer is
seated in the distributor. Hand tighten and turn an
additional 1/4 turn to seal. See Figure 8.
Note: Do not overtighten the fittings.
CAUTION
Do not over-tighten. Do not use slip joint pliers.
This distorts the aluminum distributor and the
brass fitting (potentially causing leaks).
5. Slide the nut removed in Step 3 over the supplied
liquid line. Place the supplied PTFE washer from
the TXV kit in place on the TXV and install the liquid
line to the top of the TXV. Adjust the distributor
assembly so the liquid line aligns with the hole in
the access panel. See Figure 8. Hand tighten the
liquid line and apply an additional 1/4 turn to seal.
CAUTION
The Schrader valve core must not be
installed into the suction line TXV equalizer
line fitting. Poor system performance or system
failure could result.
Figure 8: TXV installation
6. Install the TXV equalizer line onto the vapor line by
hand tightening the 1/4 in. SAE coupling nut to the
equalizer fitting and apply an additional 1/3 turn to
seal. See Figure 9.
CAUTION
Mount the TXV temperature sensing bulb after
the vapor line is brazed and sufficiently cooled.
Failure to use a suction-line split grommet may
result in TXV failure.
7. Route the temperature sensing bulb tube for the
TXV toward the vapor line header and the TXV
equalizer tube connection port on the vapor line
header.
R-410A Outdoor Split-System Air Conditioning12
Johnson Controls Ducted Systems
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