Carrier Furnace Limit Switch is Tripping
I have Carrier Furnace model 58PAV111-20 The limit switch keeps trips after running for about 5 minutes. I can reset the switch but it trips. I looked on line and found this limit switch part number is HHH18HA416. How can I tell if the limit switch bad or is something else causing this limit switch to trip? Can a bad pressure switch cause this to trip? Thanks so much for you help. Read through this thread. If you have further questions, post them on the thread you started so they don't become confused. http://forum.doityourself.com/gas-oi...-tripping.html I looked this cycle and trip off several times. It is not the limit switch tripping ever time. I noticed is getting very hot around the limit switch. Can I put a volt meter on the pressure switch to see if this I what is cussing this to trip? If yes is this 12 or 24 VDC? The fault LED when this trips is 1 long light then 3 short lights. 13. I interpreted your initial post as being the flame rollouts switch that was opening. Apparently that's incorrect and it's the limit switch that's opening. You need to verify what is turning the burners off. Use an AC voltmeter to check and see if the 24 VAC coming from the limit switch shuts off when the burners shut off. As I read your last post sometimes it's the limit switch shutting off and sometimes not. You need to describe what is happening in more detail. And yes, check to see if the pressure switch is opening. Once the thermostat calls for heat you should have 24 VAC to one side of the pressure switch, and the inducer motor should start. When the inducer motor comes up to speed the pressure switch should close and the 24 VAC should be observed on the normally open contact of the pressure switch, which would turn on the next step in the sequence of operation of the furnace. HI - Thanks for all you help. I have Carrier Model 58PAV111-20. My problem is the heater runs for a few minutes than cycles off. The LED on the PC board gives me a code 13. I put my volt meter on open contact of the pressure switch and this appears to be working OK. The limit switch gets hot and then trips. This causes the burners to turn off than I get this code 13. It now seems pretty constant the issue is when the limit switch trips. I am wondering if the limit switch should get this hot? It appears the heat is what is causing the switch to trip. What would you recommend I do next? The furnace produces a lot of heat when the burners are on. To get rid of the heat you need a constant stream of air coming from the colde air return, being heated by the furnace and being exhausted back into the house at the warm air vents. A limit switch that is opening usually implies that something is interfering with that stream of air. The most common problems are a plugged furnace filter, return air grill that is covered over, too many warm air registers closed off or an air condition evaporator coil that is plugged up from lack of having a filter in place. I'd start by checking those things out. Odds are good that one or more is causing the problem. Thanks to your direction I now have good idea where this issue coming from. Now I just need to determine best fix it. I notice a lot of Air was being sucked from the grids on the front furnace Removable door. Is this normal? The furnace is in the garage. This air sucking on caused a pressure in the garage. I noticed that it was hard to open the door into the house when the furnace was running. The limit switch does not trip if I leave the garage door open to the house or crack open the window in the garage. I checked the return air grill and it is clean and the filter is only 2 weeks old. There is is air drawing from the return air grid. For the heck of it I took out the filter and ran it. The limit switch did not trip however; I still feel this pressure in the garage when the furnace is running. The filter I put in is the same kind I have been using for years. 3M Micron Allergen Extra (1085 performance rating) Is it normal to have so much air draw from the grids on the furnace door? Should I get a lower end filter and see if this goes away? Is it possible the blower motor is starting to go bad? Or do they just go bad? Thanks for your excellent guidance!!!!!! I'm not following your last post. The furnace is in the garage. The furnace fan compartment should have a door covering it that is more or less air tight. It sounds like the return air for the furnace is being taken from the garage. That is wrong! There should be duct work for the return air which should be taken from the house. I might have given you too much info however, your last replay gave me what I info I need to resolved my issue!! Turns out I had the top furnace door on the bottom. The intake fan was sucking through this and not the return duck work from in the house. I guess I was not being careful when I replaced the filter 2 weeks ago. [B]This is all good now… THANKS SO MUCH!!!!![/B] We do more magic around here than Harry Potter! But that Voldemort is out there doing mischief.
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