PROBLEM | POSSIBLE CAUSE | TO CORRECT |
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| Outdoor thermostat does not cut off | Defective thermostat - replace. |
Unit does not heat | compressor at the preselected tem- |
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adequately. | perature and bring on heating element. |
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| Fresh air or exhaust door open. | Check if operating properly. Instruct customer |
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| on proper use of control. |
| Dirty filter. | Clean as recommended in Owner’s Manual. |
| Unit undersized. | Check heat rise across coil. Refer to perfor- |
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| mance data sheet on heat rise at various |
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| outdoor ambients. If heat rise is satisfactory, |
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| check if insulation can be added to attic or |
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| walls. |
PROBLEM |
| POSSIBLE CAUSE |
| TO CORRECT |
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| Incorrect wiring. |
| Refer to applicable wiring diagram. |
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| Defective solenoid coil. |
| Check for continuity of coil. |
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Unit cools when |
| Reversing valve fails to shift. |
| Block condenser coil and switch unit to cooling. |
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| Allow pressure to build up in system, then |
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heat is called for. |
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| switch to heating. If valve fails to shift, replace |
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| valve. |
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| Inoperative system switch. |
| Check for continuity of system switch. |
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PROBLEM |
| POSSIBLE CAUSE | TO CORRECT |
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| Outdoor thermostat does not cut off | Defective thermostat — replace. |
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| compressor at the preselected tempera- |
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| |
Unit does not heat | ture and bring on the heating element. |
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adequately. |
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Fresh air or exhaust door open. | Check if operating properly. Instruct customer on |
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| proper use of control. |
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| Dirty filter. | Clean as recommended in Owner’s Manual |
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| Unit undersized. | Check heat rise across coil. Refer to performance |
| |||
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| data sheet on heat rise at various outdoor ambients. If |
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| heat rise is satisfactory, check if insulation can be |
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| added to attic or walls. |
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PROBLEM |
| POSSIBLE CAUSE | TO CORRECT |
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Unit cools when heat is called for.
Incorrect wiring. Defective solenoid coil. Reversing valve fails to shift.
Inoperative system switch.
Refer to applicable wiring diagram. Check for continuity of coil.
Block condenser coil and switch unit to cooling. Allow pressure to build up in the system, then switch to heating. If valve fails to shift, replace valve.
Check for continuity of system switch.
PROBLEM | POSSIBLE CAUSE | TO CORRECT | ||
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| Heating capillary tube partially | Check for partially starved outer coil. Replace heating | ||
| restricted. | capillary tube. | ||
Cooling is ad- | Check valve leaking internally. | Switch unit several times from heating to cooling. | ||
| Check temperature rise across the coil. Refer to | |||
equate, but heating |
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| specification sheet for correct temperature rise. | |||
is insufficient. |
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Reversing valve failing to shift | Deenergize solenoid coil, raise head pressure, ener- | |||
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| completely — bypassing hot gas. | gize solenoid to break loose. If valve fails to make | ||
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| complete shift, replace valve. | ||
41
