Carrier flame roll out switch and issues


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Old 12-07-13, 09:44 AM
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Carrier flame roll out switch and issues

First of all, i tried to post earlier, i cant see it now. So reposting.

The heater stopped working error code 13 (initially it was 33 which turned to 13). So indicated some switch/sensor tripped. Found 2 sensors to check the air flow to heat exchanger and 2 at heat exchanger (flame roll out switch). One of the flame roll out switch, it "opens" after 30 seconds of operation. The other one stays closed. So i just bypassed it for testing and seems working fine till now. When the sensor cools down, it closes again and then it starts working.

Is this an issue with sensor? The single unit service both floors. It is not a "reset" type. I didn't find any soot or anything and all the heat exchanger shows full blue flame. Why it needs 2 flame roll out sensors?

It looks like this.
Carrier HH 18HA 452 HH18HA452 Temp Switch | eBay

Update: before even touching anything, i turned off/on the unit couple of times (the whole unit is dead cold and no firing happening). Then after i fiddle with the wires and sensor, it started working. If it is the hot sensor doing this, then the initial diagnostics should have turned it on right? I mean it is dead cold. Wonder the sensor, its loose or something like that. How this flame roll out works? Just by inside temperature in the furnace?

Also it have 5 sensors. 2 on in, 2 on out and one in the exhaust vent. The exhaust vent is hot indicating it is working fine

Thanks..
 

Last edited by saneesh8; 12-07-13 at 10:55 AM.
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Old 12-07-13, 11:52 AM
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If you want to replace the sensor read the limit number on it.
Bypassing rollout switches is unsafe for anything other than testing purposes.
 
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Old 12-07-13, 01:02 PM
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The limit switch is 210-40. So high cutoff is 210F and then ON at 170F?

I checked the temperature at both sensors (after removing it, inserted a meat thermometer). The one which is working, it is like ~100F and the one where it is not working, it is above 210F which is why it is cutting off. So the sensor is working fine.

I checked all the vents and all are getting hot air indicating that the air flow to the vents are fine. I guess the working sensor is on this one.

The sensor where it is not working, it is there the outside vent is going. Is it checking the flow on air going outside also? I wonder if some ice formed on the roof is causing this issue (restricting air flow). How to check it for sure? Can i disconnect the vent and try it ? Just to check it?

I guess
 
 

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