Carrier 58MVP Troubleshooting Manual page 26

STEP
19. Fix problem.
20. Put setup switch SW-6 for COMPONENT TEST in OFF position.
21. Jumper R and W/W1 thermostat terminals on furnace control board.
Connect an AC voltmeter across BLUE and GREEN wires to gas valve GV.
22.
Does gas valve GV receive 24v?
23. Turn power off.
Do you have continuity across the following connections:
24. • PL1-2 and BLUE wire at gas valve GV.
• PL1-7 and GREEN wire at gas valve GV.
The BLUE or GREEN wire from furnace control board to gas valve GV is not
25.
making good connection. Repair wire(s) or replace harness.
26. Does gas valve open and allow gas to flow?
27. Are all manual gas cocks in ON position?
28. Do main burners ignite?
Check for the following:
29. • Inadequate flame carryover or rough ignition.
• Low inlet gas pressure.
30. Do main burners stay on?
Turn power off and disconnect jumper wire across R and W/W1 thermostat ter-
31.
minals.
32. Connect a DC microammeter in series with flame sensor wire.
Turn power on and wait several sec then jumper R and W/W1 thermostat termi-
33.
nals on furnace control board.
34. Is DC current below 0.5 microamps?
Check connections and recheck current. If current is near typical value and con-
35.
trol will not stay on, replace furnace control board.
Clean flame sensor with fine sandpaper and recheck current. Current is typically
36.
4.0 to 6.0 microamps.
37. Is current near typical value?
38. Replace electrode.
39. Will main burners ignite and stay on?
40. Do you have combustion pulsations?
41. Make sure perforated disks are in combustion-air vent inlet.
42. Check pressure tubing going to gas valve air pressure fitting for kinks.
43. Remove gas valve air pressure fitting and check gas valve for blockage.
44. Ensure vent and combustion-air pipes are not reversed.
45. Check burner orifice size and alignment.
46. Add restriction to combustion-air pipe or lengthen it a few feet if possible.
47. Jumper R and W2 thermostat terminals on furnace control board.
48. Do you have combustion oscillations in high fire?
Fault Code 41
BLOWER OUTSIDE VALID SPEED RANGE—This fault indicates 1 of the following:
• Blower motor speed cannot be maintained within 10% of calculated speed over a 30-sec period.
• Blower motor speed is less than 250 RPM or greater than 1300 RPM for more than 10 sec.
STEP
Turn power off, remove blower access panel, and disconnect R thermostat lead
1.
from furnace control board.
Turn power on and depress door switch. Use a piece of tape to hold switch
2.
closed.
3. Jumper R and W/W1 thermostat terminals on furnace control board.
4. Observe operation of furnace for next 8 minutes or until fault occurs.
5. Does Fault Code 44 flash twice followed by Fault Code 41?
After about 10 minutes of operation, furnace will lock out and flash Fault Code
6.
12. Go to page number indicated in Index for Fault Code 12.
7. Does only Fault Code 41 flash?
8. Does a different fault occur?
9. Go to page number indicated in Index for fault code flashed.
26
YES NO GO TO
— — 8
— — 21
— — 22
26 23 —
— — 24
17 25 —
— — 12
28 27 —
11 19 —
30 29 —
— — 19
40 31 —
— — 32
— — 33
— — 34
36 35 —
— — 12
— — 37
39 38 —
— — 12
12 17 —
41 47 —
— — 42
— — 43
— — 44
— — 45
— — 46
— — 12
— — 48
41 12 —
YES NO GO TO
— — 2
— — 3
— — 4
— — 5
6 7 —
— — INDEX
11 8 —
9 25 —
— — INDEX