XTS Common Parts

				
					Act as an expert systems troubleshooter. I am going to give you a Mermaid.js flowchart that represents our system's architecture/workflow. Your goal is to help me diagnose an issue by stepping through this flowchart with me interactively, one node at a time. 

%% Troubleshooting Flowchart for XTS
%% Manufacturing date range 08/1999 to 05/2003
%% Source: xts_manual0500.pdf
%% Pages: 8-9
graph LR
    %% Page 1: Initial Troubleshooting & Fan/Ignitor Checks
    Start([Turn up Thermostat]) --> Q1{Does the fan<br>blower turn on?}
    
    %% Fan blower NO branch
    Q1 -- NO --> Q2{Is the power at the<br>heater 120V?}
    Q2 -- NO --> A1[Find the source of the<br>electrical problem.]
    Q2 -- YES --> Q3{Is the blower<br>obstructed?}
    Q3 -- YES --> A2[Remove obstruction<br>& lubricate fan.]
    Q3 -- NO --> Q4{Is there 120V<br>coming to the fan?}
    Q4 -- NO --> A3[Correct wiring.]
    Q4 -- YES --> A4[The fan is faulty and<br>must be replaced.]
    
    %% Fan blower YES branch -> Ignitor checks
    Q1 -- YES --> Q5{Does the ignitor<br>warm up and glow red?}
    
    Q5 -- NO --> Q6{Is the ignitor<br>physically damaged?}
    Q6 -- YES --> A5[Replace ignitor.]
    Q6 -- NO --> Q7{Check voltage at ignitor during ignition<br>sequence 30-45s after power.<br>Is it 120V?}
    
    Q7 -- YES --> Q8{Is the resistance through<br>the ignitor 45-400Ω?}
    Q8 -- NO --> A5
    
    Q7 -- NO --> Q9{Is the inlet or outlet of the unit<br>obstructed? e.g., ice, birds nest, dirt}
    Q9 -- YES --> A6[Remove obstruction.]
    Q9 -- NO --> Q10{Check for loose wiring/restrictions in<br>hose connections to pressure switch.<br>Are they ok?}
    Q10 -- NO --> A7[Repair wiring or hose<br>connections.]
    
    Q10 -- YES --> Q11{Safety pressure switches: Temporarily place<br>jumpers across terminals of each switch,<br>one at a time with cover reinstalled.<br>Does ignitor glow red?}
    Q11 -- YES --> A8[Replace appropriate switch after verifying:<br>- Baffles are in farthest tubes<br>- Heater/blower/intake/exhaust are clean<br>- 4in intake pipe is <= 20ft and/or 2 elbows<br>- No negative pressure at air intake]
    
    Q11 -- NO --> Q12{Temporarily place jumpers across both pressure<br>switches and check for 120V going from<br>switch to circuit board. Is there 120V<br>entering the circuit board?}
    Q12 -- NO --> A9[Faulty wiring. Repair or<br>replace wiring.]
    Q12 -- YES --> A10[Replace circuit board.]

    %% Page 2: Gas Valve & Burner Operation
    Q5 -- YES --> Q13{After ignitor is warmed up,<br>does gas valve open?}
    
    %% Gas Valve NO branch
    Q13 -- NO --> Q14{Test for 120V at valve during valve opening<br>period 30-45s after power to heater.<br>Is there 120V to valve?}
    Q14 -- NO --> A11[Possibly, the circuit board and/or<br>wiring harness is faulty. Replace them.]
    Q14 -- YES --> Q15{Check gas pressure within min/max inputs<br>on AGA burner rating label.<br>Is gas pressure OK?}
    Q15 -- NO --> A12[Correct problem.]
    Q15 -- YES --> A13[Replace gas valve.]

    %% Gas Valve YES branch -> Burner lighting
    Q13 -- YES --> Q16{Does the burner light?}
    Q16 -- NO --> Q17{Is the gas cock in<br>an ON position?}
    Q17 -- NO --> A14[Correct problem.]
    Q17 -- YES --> Q18{Check gas pressure within min/max inputs<br>on AGA burner rating label.<br>Is gas pressure OK?}
    Q18 -- NO --> A15[Correct problem.]
    Q18 -- YES --> A16[Make sure gas lines<br>were purged of air.]

    %% Burner Stay On Checks
    Q16 -- YES --> Q19{Does the burner<br>stay on?}
    
    %% Burner stays on -> Final operation
    Q19 -- YES --> Q20{Does heater stay on<br>until call for heat ends?}
    Q20 -- YES --> End([Troubleshooting ends.])
    Q20 -- NO --> Box1[The following can cause the heater to shut down:<br>- Improper grounding<br>- High winds<br>- Taking combustion air from the attic<br>- Dirty environment<br>- Baffle not located properly<br>- Fluctuating gas pressure]
    
    %% Burner does NOT stay on -> Diagnostics
    Q19 -- NO --> Q21{Does the burner stay on for<br>approx. 8 seconds and then shut off?}
    
    %% Stays on 8 seconds
    Q21 -- YES --> Q22{Is the heater properly grounded?<br>Is the heater's polarity correct?}
    Q22 -- NO --> A17[Correct problem.]
    Q22 -- YES --> Q23{With voltmeter, check DC voltage at flame rod.<br>Is it greater than 30 Volts DC?}
    Q23 -- YES --> A18[Check to make sure flame sensor wire is<br>OK and then replace circuit board.]
    Q23 -- NO --> A19[Sensing rod is faulty or flame is weak.<br>Check heater operating gas pressure on AGA label<br>and replace sensing rod if needed.]
    
    %% Shuts off immediately (1-2 seconds)
    Q21 -- NO --> Q24{Does the burner come on and then<br>turn off immediately 1 or 2 seconds?}
    Q24 -- YES --> Q25{Check pressure within min/max inputs<br>on AGA burner rating label.<br>Is gas pressure OK?}
    Q25 -- NO --> A20[Correct problem.]
    Q25 -- YES --> A21[Exhaust pressure switch may be<br>faulty or there is a restriction in the exhaust.]

    %% Style Definitions
    classDef startEnd fill:#d4ebf2,stroke:#333,stroke-width:2px,color:#000;
    classDef decision fill:#fff2cc,stroke:#d6b656,stroke-width:2px,color:#000;
    classDef action fill:#d5e8d4,stroke:#82b366,stroke-width:1px,color:#000;
    classDef fault fill:#f8cecc,stroke:#b85450,stroke-width:1px,color:#000;
    classDef info fill:#e1d5e7,stroke:#9673a6,stroke-width:1px,color:#000;

    %% Apply Classes
    class Start,End startEnd;
    class Q1,Q2,Q3,Q4,Q5,Q6,Q7,Q8,Q9,Q10,Q11,Q12,Q13,Q14,Q15,Q16,Q17,Q18,Q19,Q20,Q21,Q22,Q23,Q24,Q25 decision;
    class A1,A2,A3,A6,A7,A12,A14,A15,A16,A17,A20 action;
    class A4,A5,A8,A9,A10,A11,A13,A18,A19,A21 fault;
    class Box1 info;