Carrier 48AK Installation, Start-up And Service Instructions Manual

Also see for 48AJ: Installation instructions Operation and service guide Started guide Operating and service guide

Contents

43Routing Through Bottom of Unit — If wiring is brought inthrough bottom of unit, use field-supplied watertight conduit torun power wiring from basepan out through bottom 31/2-in.hole to the disconnect box and back into unit to the main con-trol box.Use strain relief going into control box through 21/2-in. di-ameter hole provided. After wires are in unit control box, con-nect to power terminal block (see Power Wiring section onpage 33).Low-voltage wiring must be run in watertight conduit fromthe basepan to control box and through 7/8-in. diameter holeprovided in bottom of unit control box. Field-supplied strain re-lief must be used going into the box. After wiring is in controlbox, make connections to proper terminals on terminal blocks(see Field Control Wiring section on this page).Install conduit connector in unit basepan as shown inFig. 5-16. Route power and ground lines through connector toterminal connections in unit control box as shown on unit wir-ing diagram and Fig. 28.Routing Through Side of Unit — Route power wiring infield-supplied watertight conduit into unit through 21/2-in. or3-in. hole. See Fig. 28.Use field-supplied strain relief going into control boxthrough 21/2-in. or 3-in. diameter hole provided. After wires arein unit control box, connect to power terminal block (see Pow-er Wiring section on page 33).Bring low-voltage control wiring through factory-drilled7/8-in. diameter hole in condenser side post. Use strain reliefgoing into 7/8-in. diameter hole in bottom of unit control box.After wiring is in control box, make connection to properterminals on terminal blocks (see Field Control Wiring sectionbelow).Affix crankcase heater sticker (located in the installers pack-et) to unit disconnect switch.Voltage to compressor terminals during compressor opera-tion must be within the voltage range indicated on the unitnameplate. On 3-phase units, phases must be balanced within2%.Use the formula in Tables 7 and 8 to determine the percent-age of voltage imbalance.Unit failure as a result of operation on improper line voltageor excessive phase imbalance constitutes abuse and may causedamage to electrical components.On 208/230-v units, transformer no. 1 is wired for 230-v. If208/230-v unit is to be run with 208-v power supply, the trans-former must be rewired as follows:1. Remove cap from red (208 v) wire.2. Remove cap from spliced orange (230 v) wire. Discon-nect orange wire from black unit power wire.3. Cap orange wire.4. Splice red wire and black unit power wire. Cap wires.FIELD CONTROL WIRING — Install either a Carrier-approved thermostat or a CCN (Carrier Comfort Network)compatible temperature sensor. Thermostats are used on CV(constant volume) units only. Control box diagrams are shownin Fig. 29-31.IMPORTANT: The VAV (variable air volume) units usevariable frequency drives, which generate, use and canradiate radio frequency energy. If units are not installed andused in accordance with these instructions, they may causeradio interference. They have been tested and found tocomply with limits of a Class A computing device asdefined by FCC (Federal Communications Commission)regulations, Subpart J of Part 15, which are designed toprovide reasonable protection against such interferencewhen operated in a commercial environment.The unit must be electrically grounded in accordance withlocal codes and NEC ANSI/NFPA 70 (National Fire Pro-tection Association).IMPORTANT: If the supply voltage phase imbalance ismore than 2%, contact your local electric utility companyimmediately.IMPORTANT: BE CERTAIN UNUSED WIRES ARECAPPED. Failure to do so may damage the transformers.Fig. 28 — Field Power Wiring ConnectionsLEGENDGND — GroundNEC — National Electrical CodeTB — Terminal Block