Carrier Series 100 Troubleshooting Guide

-1- Replaces: NEW Form: 58MVC-01T 10-08 Variable Speed, Step-Modulating Electronic Condensing Four-Way Multipoise Gas Furn

- 10 - START HERE - If a problem exists, the service technician should always begin troubleshooting here. SPECIAL NOTE: ALL VOLTMETERS ARE NOT THE SA

- 11 - STEP ACTION YES NO GO TO 26. Is 115-vac across the transformer leads? 27 25 27. Replace the transformer. 18 28. Is 24-vac across

- 12 - IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not properly connected. If User Interface is connected to

- 13 - Table 2 – Cooling Tonnage vs. Airflow (CFM) AIR CONDITIONING TONS (12,000 BTU/HR) AIRFLOW (CFM) 060, & 3T-080 MODEL 5T-080 & 100 MODE

- 14 - STEP ACTION YES NO GO TO 11. Go to the page number indicated in Index for the CLEANUP AND STARTUP INSTRUCTIONS. INDEX 12. Replace the ga

- 15 - Status Code 11 NO PREVIOUS CODE - Stored status codes are erased after 72 hours or can be cleared by jumpering R, W/W1, and Y/Y2 thermostat l

- 16 - STEP ACTION YES NO GO TO 21. Does the furnace abruptly shut down with no inducer post purge and then run blower motor BLWM for 90 seconds w

- 17 - STEP ACTION YES NO GO TO 26. Does furnace have the proper limit switch, limit shield, blower baffle (if used), and rear air baffle (if used

- 18 - STEP ACTION YES NO GO TO 17. Cycle the furnace several times to check for intermittent operation. 18 18. Does status code 21 ever fla

- 19 - Status Code 24 SECONDARY VOLTAGE FUSE IS OPEN - Indicates fuse is open and there is a short in low-voltage wiring. STEP ACTION YES NO GO TO

- 2 - You should ALWAYS begin in the START HERE section (see Index for page number) which will guide you to the appropriate section where a minimal nu

- 20 - STEP ACTION YES NO GO TO 39. Do you have continuity between the GRAY wire connected to both the medium and high heat pressure switches and

- 21 - Status Code 25 MODEL SELECTION OR SETUP ERROR – If status code 25 only flashes 4 times on power-up the variable speed furnace control is miss

- 22 - Status Code 31 MEDIUM-HEAT PRESSURE SWITCH OR HPSR RELAY DID NOT CLOSE OR REOPENED - This status code can occur under the scenarios shown be

- 23 - pressure switch MPS remakes the variable speed furnace control continues heating cycle. If medium heat pressure switch MPS does not remake wi

- 24 - STEP ACTION YES NO GO TO 41. Did the pressure gradually drop over time until the fault occurred? If the pressure remained constant and the

- 25 - STEP ACTION YES NO GO TO 16. Fix problem. 8 17. Does status code 32 flash once then flash status code 43? 18 19 18. On propane inst

- 26 - Status Code 33 LIMIT CIRCUIT FAULT - This status code indicates the limit, or flame rollout switch is open or the furnace is operating in hi

- 27 - STEP ACTION YES NO GO TO 40. Remove tape from door switch, turn power off at main disconnect, and remove jumper across R and W/W1. 41 41.

- 28 - Status Code 34 IGNITION-PROVING FAULT - This status code indicates flame was not sensed during trial for ignition period. The control will

- 29 - STEP ACTION YES NO GO TO 32. Clean flame sensor with fine steel wool and make sure it is properly positioned then recheck current. Current

- 3 - This furnace can operate as a step-modulating furnace with a single-stage thermostat because the furnace control CPU includes a programmed adap

- 30 - Status Code 41 BLOWER MOTOR FAULT - This status code indicates the blower failed to reach 250 RPM or the blower failed to communicate to the

- 31 - STEP ACTION YES NO GO TO 28. Check the blower motor serial output signal. To do this disconnect PL3 from the furnace control and connect a

- 32 - STEP ACTION YES NO GO TO 47. When blower control module is completely detached from blower motor, verify with standard ohmmeter that the res

- 33 - STEP ACTION YES NO GO TO 33. Reconnect collector box tube to pressure switch assembly. 40 34. Disconnect jumper across R and W/W1 the

- 34 - Status Code 43 LOW-HEAT PRESSURE SWITCH OPEN WHILE MEDIUM-HEAT PRESSURE SWITCH IS CLOSED - This status code can occur as a result of the low

- 35 - CLEANUP AND START-UP INSTRUCTIONS 1. Start furnace using procedure outlined on Lighting Instructions attached to furnace. Observe operatio

- 36 - APPENDIX A BOARD LAYOUT AND WIRING SCHEMATICS Fig. 1 – Variable Speed Furnace Control 24-V THERMOSTAT TERMINALS PL2 – HOT SURFACE IGNIT

- 37 - Fig. 2 – Wiring Schematic

- 38 - APPENDIX B ECM BLOWER MOTOR DESCRIPTION & OPERATION The Regal-Beloit Electronically Commutated Motor (ECM) shown in figure 3 is the

- 39 - Figure 3 – ECM Blower Motor

- 4 - to medium-heat airflow five seconds after the furnace control CPU switches from low-heat to medium-heat. Switching from Low- to High-Heat –

- 40 - APPENDIX C PRESSURE CHECK DIAGRAM PRESSURE SWITCH MAKE/BREAK POINTS HIGH-HEAT PRESSURE SWITCH MED-HEAT PRESSURE SWITCH LOW-HEAT PRESSU

- 41 - APPENDIX D STATIC PRESSURE READING LOCATION DIAGRAMS Figure 5 – Upflow Total Static Pressure Reading Locations Figure 6 – Downflow

- 42 - Tools Needed: 1. Pitot Tube 2. Incline Manometer/Magnahelic Example 1: Return ESP after Filter 0.20 in.w.c. Supply ESP

- 43 - APPENDIX E QUICK REFERENCE INFORMATION PRESSURE SWITCH MAKE/BREAK POINTS HIGH-HEAT PRESSURE SWITCH MED-HEAT PRESSURE SWITCH LOW-HEAT P

- 44 - APPENDIX F FURNACE STAGING ALGORITHM On initial thermostat call for heat after power-up, furnace staging algorithm will provide 1 minute

- 45 - Using recorded Low Heat (LH), Medium Heat(MH), and High Heat (HH) values calculate theHeat Load (HL) using:HL=(140xLH)+(228xMH)+(350x

- 46 - SERVICE TRAINING Packaged Service Training programs are an excellent way to increase your knowledge of the equipment discussed in this

- 47 -

- 48 - Replaces: NEW Form: 58MVC-01T 10-08

- 5 - 4. COOLING MODE The thermostat "calls for cooling". a. Single-Speed Cooling The thermostat closes the R to G-and-Y circuits. T

- 6 - The electronic air cleaner terminal EAC-1 is energized with 115 vac whenever the blower motor BLWM is operating. When the thermostat is satisf

- 7 - desired and is stored in the memory to be automatically used following a power interruption. 8. HEAT PUMP DEFROST When installed with a hea

- 8 - SERVICE/STATUS CODE INSTRUCTIONS If status code recall is needed disconnect the “R” thermostat lead, reset power, and put setup switch “SW1

- 9 - 33 LIMIT CIRCUIT FAULT – Indicates the limit, or flame rollout is open or the furnace is operating in high-heat only mode due to 2 successive