CONQUEST 90 - Service Analyzer Charts

SERVICEANALYZERCHARTS
SYMPTOMS POSSIBLE CAUSES CHECK/REMEDIES
1. Igniter won't heat (HSI)
or spark (DSI)
Broken or cracked igniter,
or igniter ceramic
Replace igniter
Frayed or damaged wiring
or junction plug
Replace igniter or wiring harness
No voltage to igniter Check wiring; check IFC board;
replace if necessary
Open pressure switch Refer to "pressure switch checks"
2. Sensor doesn't sense flame
Line power polarity reversed Check polarity and correct as
necessary
Damaged wiring or connection to IFC Replace wiring or correct as
necessary
Insufficient flame Check/adjust gas pressure as
necessary
Improper furnace grounding Correct furnace grounding
Sensor out of position Correct sensor positioning
Coated flame sensor Clean with emory cloth
Damaged IFC board Replace IFC
3. Excessive burner cycling Dirty filters Clean or replace
Cycling on limit Restricted air flow;
Overtired furnace
Insufficient return air or low air flow Check unit temperature rise;
Check fan speed
Thermostat incorrectly installed; Check location for drafts;
Check anticipator setting;
Level thermostat subbase
Incompatible thermostat
(e.g. some setback thermostats)
Change thermostat;
Install isolation relay;
Install 100 Ohm 10 watt resistor
Thermostat failure;
improper anticipator setting
Replace thermostat;
set heat anticipator;
add 100 Ohm, 10 watt resistor
Fluctuating gas pressure Check gas pressure with all
appliances operating; check gas
line sizing
Improper furnace grounding Correct furnace wiring
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