SECTION VII – TROUBLESHOOTING

System without Pilot

Symptom

 

Cause

 

Remedy

 

 

 

 

 

A. If blower does not operate.

1.

Low or no voltage.

1.

Check power source.

 

2.

Fuse(s) blown.

2.

Check and replace.

 

3.

Customer interlock not closed

3.

Close or connect customer

 

 

or connected.

 

interlock.

 

4.

Fan Off-On switch in Off position.

4.

Switch to On position.

 

5.

Time clock, night setback thermo-

5.

Check time clock, night setback

 

 

stat or field installed controls

 

thermostat and field installed

 

 

open.

 

controls for proper settings.

 

6.

Freeze protection tripped.

6.

Reset freeze stat by interrupting

 

 

 

 

power. Check for proper setting

 

 

 

 

and burner operation.

 

7.

Damper motor not operating, or

7.

Check for power at damper motor

 

 

its end switch not making.

 

and that end switch has been wired

 

 

 

 

correctly to the N.O. (normally

 

 

 

 

open) contact. Check that the

 

 

 

 

linkage is clear and not binding.

 

8.

Overload protection on motor

8.

Push reset button on starter and

 

 

starter tripped.

 

check amps.

 

9.

Belts loose or broken

9.

Turn power off and check belts.

 

10.

Bearings seized.

10.

Check and replace.

 

11.

Motor may be burned or incor-

11.

Turn power off and check motor

 

 

rectly wired.

 

and wiring.

 

12.

Motor overheating.

12.

Check burner firing rate.

 

 

 

 

 

B. If there is no voltage at ignition

1.

Heat Off-On switch in Off

1.

Switch to On position.

control.

 

position.

 

 

 

2.

Burner enable relay open

2.

Check for power and replace if

 

 

(if applicable).

 

necessary.

 

3.

Outside air temperature higher

3.

Lower On-Off inlet ductstat

 

 

than On-Off inlet ductstat

 

setting.

 

 

(if applicable).

 

 

 

4.

Field purge timer open

4.

Check for power and replace if

 

 

(if applicable).

 

necessary.

 

 

 

 

 

C. Burner does not light after 5 sec-

1.

Manual gas shut-off valve closed.

1.

Slowly open valve.

onds pre purge of flame safeguard

2.

Inlet gas pressure lower than

2.

Increase gas pressure.

relay and there is voltage at igni-

 

required gas pressure.

 

 

tion control.

3.

Type of gas (Natural, LP) supplied

3.

Replace with factory required

 

 

different from factory required

 

type of gas.

 

 

type.

 

 

 

4.

Auxiliary switch on starter not

4.

Check for power and replace if

 

 

closed.

 

necessary.

 

5.

Air flow switches not closing.

5.

Adjust the air flow and external

 

 

 

 

static pressure to match rating

 

 

 

 

plate.

 

6.

High temperature limit switch

6.

Correct problem. Reset by pushing

 

 

open.

 

down the reset button.

 

7.

High or low gas pressure switches

7.

Correct problem. Reset both

 

 

open (if applicable).

 

switches.

 

8.

Main gas valve relay open.

8.

Check for power and replace if

 

 

 

 

necessary.

 

 

 

 

 

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