Carrier 58MVP Troubleshooting Manual

Also see for GAS FURNACE 58MVP: Installation, start-up, and operating instructions User's information manual User manual User's information manual User's information manual

Contents

Carrier 58MVP Troubleshooting Manual Manual pdf 24 page image

29. Is inducer blower wheel okay? 31 30 —30. If possible, replace inducer blower wheel. Otherwise, replace inducer motor assembly. — — 1031. Is there any frost build-up on combustion-air inlet? 32 33 —32. The problem is caused by reversed vent and combustion-air pipes or some other moist air enteringcombustion-air pipe. — — 2733. You have excessive restriction in combustion-air or vent pipe. — — 1034. The problem is either a sag in vent pipe or a clogged drain trap or line. — — 2735. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 3636. Turn power on and wait several sec, then jumper R and W/W1 thermostat terminals on furnace con-trol board. — — 3737. Do you have 24v between connector terminal PL2-2 and Com on furnace control board when faultoccurs? 13 38 —38. Turn power off. — — 3939. Do you have continuity across terminal PL2-2 and N.O. (Normally Open) contact on low-pressureswitch LPS? 16 40 —→40.The ORANGE wire from low-pressure switch LPS to furnace control board is not making good con-nection or low gas pressure switch LGPS (when used) is open. Check propane line pressure if us-ing LGPS otherwise repair wire or replace harness.— — 2741. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 4242. Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other sidewith a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C. — — 4343. Turn power on and wait several sec, then jumper R and W/W1 thermostat terminals on furnace con-trol board. — — 4444. Monitor slope manometer. Does pressure reading appear to be stable when fault occurs? 45 46 —45. Replace pressure switch assembly. If problem persists, check wiring for an intermittent connectionin low-pressure switch LPS circuit. — — 1046. Check for a sag in vent pipe. If problem persists, replace inducer motor. — — 1047. Do you have 24v between connector terminal PL2-2 and Com on furnace control board? 48 13 —48. The main harness is miswired. — — 2749.Check Inducer PW line. To do this, disconnect PL7 from inducer motor and connect a DC voltmeteracross terminals PL7-2 BROWN (+) and PL7-10 YELLOW (-) then run COMPONENT TEST byturning setup switch SW-6 ON. Does voltage across PL7-2 and PL7-10 change between states asshown below?• State 1—OFF (-0.1 — 0.1 vdc)• State 2—LOW (6.0 — 7.0 vdc)• State 3—HIGH (10.5 — 11.5 vdc)26 13 —50. Does inducer motor MTR1 turn on? 19 51 —51. Do you have less than 90 vac between I1 and I2 on furnace control board? 53 52 —52.Check Inducer PW line. To do this, disconnect PL7 from inducer motor and connect a DC voltmeteracross terminals PL7-2 BROWN (+) and PL7-10 YELLOW (-) then run COMPONENT TEST byturning setup switch SW-6 ON. Does voltage across PL7-2 and PL7-10 change between states asshown below?• State 1—OFF (-0.1 — 0.1 vdc)• State 2—LOW (6.0 — 7.0 vdc)• State 3—HIGH (10.5 — 11.5 vdc)26 13 —53. Make sure wire gage between main fuse box and furnace complies with wire size specification inInstallation, Start-Up, and Operating Instructions. — — 27→54. Does the fault occur before ignition 45 sec after call for heat? 50 41 —→55. Check propane line pressure if using low gas pressure switch LGPS otherwise go to step 41. — — 27Fault Code 33LIMIT SWITCH FAULT—This fault indicates the limit switch, rollout switch or auxiliary limit switch is open orunit is operating in high-heat only mode due to 2 successive low-heat limit trips.STEP ACTION YES NO GO TO1. Turn power off, remove blower access panel, and disconnect R thermostat lead. — — 22. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 33. Is the fault code flashing? 11 4 —4. Set thermostat to call for heat or jumper R and W/W1 thermostat terminals. — — 55. Observe operation of furnace for next 25 minutes. — — 66. Does fault occur again? 40 7 —7. Does a different fault occur? 8 9 —8. Go to page number indicated in Index for fault code flashed. — — INDEX24