Carrier 58MCA Service And Maintenance Instructions

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Contents

Carrier 58MCA Service And Maintenance Instructions Manual pdf 6 page image

16. Check furnace operation through 2 complete heat operatingcycles. Look through sight glass in burner enclosure to checkburners. Burner flames should be clear blue, almost transpar-ent. (See Fig. 10.)17. Check for gas leaks.Never use matches, candles, flame, or other sources ofignition to check for gas leakage. Use a soap-and-watersolution. Failure to follow this warning could result in a fire,personal injury, or death.18. Replace furnace door.SECONDARY HEAT EXCHANGERSNOTE: The condensing side (inside) of the secondary heatexchangers CANNOT be serviced or inspected. A small number ofbottom outlet openings can be inspected by removing the inducerassembly. See Step 5 — Flush Collector Box and Drainage Systemfor details on removing inducer assembly.Step 5—Flush Collector Box and Drainage System1. Turn off gas and electrical supplies to furnace.2. Remove furnace door.3. Disconnect inducer motor and pressure switch(es) wires orconnectors.4. Disconnect pressure switch tubes.5. Disconnect vent pipe from inducer housing outlet by loosen-ing clamp.6. Disconnect drain tube from inducer housing. (See Fig. 8 or 9.)7. Remove inducer housing assembly by removing 4 boltsattaching assembly to cell panel.8. Flush inside of collector box with water until discharge fromcondensate trap is clean and runs freely.NOTE: Ensure the drain tube disconnected from the inducerhousing is higher than the collector box opening or water will flowout tube.9. Inspect inside area of collector box for any pieces of foreignmaterials and remove if present.DO NOT use wire brush or other sharp object to inspect ordislodge materials in secondary heat exchangers as failure ofthe secondary heat exchanger will occur. Flush with wateronly.10. Reassemble inducer assembly by reversing items 5. through 7.NOTE: If seal between the inducer housing and the collector boxis damaged in any way, it must be repaired. To repair, applysealant releasing agent (PAM cooking spray or equivalent, mustnot contain corn or canola oil, aromatic or halogenated hydrocar-bons) to inducer housing. (See Fig. 11.) Apply a small bead of G.E.RTV 162 or Dow-Corning RTV 738 sealant to groove in collectorbox.11. Refer to furnace wiring diagram and connect wires to inducermotor and pressure switch(es) or connectors.12. Reconnect pressure tubes to pressure switch(es). See diagramon main furnace door for proper location of tubes. Be suretubes are not kinked. (See Fig. 8 or 9.)13. Turn on gas and electrical supplies to furnace.14. Check furnace operation through 2 complete heat operatingcycles. Check area below inducer housing, vent pipe, andcondensate trap to ensure no condensate leaks occur. If leaksare found, correct the problem.15. Check for gas leaks.Never use matches, candles, flame, or other sources ofignition to check for gas leakage. Use a soap-and-watersolution. Failure to follow this warning could result in a fire,personal injury, or death.16. Replace furnace door.Step 6—Service Hot Surface IgnitorThe ignitor does NOT require annual inspection. Check ignitorresistance before removal.1. Turn off gas and electrical supplies to furnace.2. Remove furnace door.3. Disconnect ignitor wire connection.4. Check ignitor resistance.a. Using an ohm meter, check resistance across both ignitorleads in connector.b. Cold reading should be between 45 ohms and 90 ohms.c. If ohm reading is higher than 110 ohms, ignitor is crackedand must be replaced.5. Remove ignitor.a. While spreading ignitor bracket legs outward, use hand toGENTLY guide ignitor out of burner box.The ignitor is fragile. DO NOT allow it to hit the side of theburner box opening while removing or replacing it.b. Inspect ignitor for a white area indicating a crack may bepresent. If found, replace ignitor.NOTE: A small crack cannot be seen on a new ignitor. After aperiod of operation, a white area will be visible around the crack.6. After inspecting or replacing ignitor, install it into burner boxby gently pushing ignitor into bracket until bracket legs fullysecure ignitor. (See Fig 12.)7. Connect ignitor wire connection.8. Turn on gas and electrical supplies to furnace.9. Check furnace operation through 2 heat operating cycles.10. Replace furnace door.Step 7—Electrical Controls and WiringThere may be more than 1 electrical supply to the unit. Checkaccessories and cooling unit for additional electrical supplies.The electrical ground and polarity for 115-v wiring must bemaintained properly. Refer to Fig. 13 for field wiring informationand to Fig. 18 or 22 for unit wiring information.NOTE: If the polarity is not correct, the STATUS LED on thecontrol center will flash rapidly and prevent the furnace fromoperating. The control system also requires an earth ground forproper operation of the control center and flame sensing.The 24-v circuit contains an automotive-type, 3-amp fuse locatedon the control center. (See Fig. 14 and 15.) Any direct shorts of the24-v wiring during installation, service, or maintenance will causethis fuse to blow. If fuse replacement is required, use ONLY a fuseof identical size.6