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Question

The blower is going on even when the stat is off. I am not getting any heat. The board is signaling the limit control circuit is open. Schematic doesn't show it. Can I Jump this?

Submitted: 324 days and 12 hours ago.
Category: HVAC
Value: $15
Status: AWAITING CUSTOMER ACTION
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Posted by alex hewitt 324 days and 11 hours ago.

Answer

Hi

 

Jump the stat.The board should then see a closed circuit and call for heat.

 

Stats are only a type of switch

 

Thanks

 

Alex

 

 

324 days and 10 hours ago.

Reply

how can you bypass the stat? Do you have to tie anything together?

Posted by alex hewitt 324 days and 10 hours ago.

Answer

Hi

 

On all stats you have a live feed in and a swiched live out when its made.

 

You need to link the live in with the switched live out.

 

In a 2 wire stat link the two

In a 2 wire plus neutral link the two lives leave the neutral

Rare 3 wire is a satisfied live output so link feed in with demand out.

 

What stat is it?

 

Alex

324 days and 10 hours ago.

Reply

I have Red, White, Green and Yellow.

Posted by coolman1973 324 days and 10 hours ago.

Answer

if ur getting a high limit code it means ur heat exchanger is overheating, the blower is supposed to come on as to cool the furnace, if this is what is going on i cant see how the tstat has anything to do with it

324 days and 10 hours ago.

Reply

Will the blower cool the furnace as a safety feature? Can I let the unit run until it calls for heat?

Posted by coolman1973 324 days and 10 hours ago.

Answer

shut the power off to the furnace and back on , see if the blower stays off

324 days and 9 hours ago.

Reply

The blower comes on almost immediately after power back on.

Posted by coolman1973 324 days and 9 hours ago.

Answer

did the code go away ?

324 days and 9 hours ago.

Reply

No. 1 red flash saying limit circuit open.

Posted by coolman1973 324 days and 9 hours ago.

Answer

u need to look around prob by the burners or on the flue pipe coming out of the top of the furnace for limit switchs with reset buttons on them

324 days and 9 hours ago.

Reply

That is a dime size disc with 2 terminals? There is something that looks like a button, but does not push in, or click. Just loose. Could it just be an automatic switch?

Posted by coolman1973 324 days and 9 hours ago.

Answer

there should be more than one ? but ya thats it, does that have codes of limit switch and high limit as seperate codes? also if the flue pipe coming off the top of the furnace has a little draft hood on in look up in there for a limit

324 days and 9 hours ago.

Reply

Yes. Same thing. Looks like a button, but doesn't push in to reset.

Posted by coolman1973 324 days and 9 hours ago.

Answer

ok look between the burners and inducer motor there should be a highlimit switch mounted inside the furnace prob 2 wires, jump them together

324 days and 9 hours ago.

Reply

What color would the wires be? Are they white w/ black stripes and black w/ white stripes?

Posted by coolman1973 324 days and 9 hours ago.

Answer

i dont know but they should just be right on either side of the high limit

324 days and 8 hours ago.

Reply

How can they be spliced?

Posted by coolman1973 324 days and 8 hours ago.

Answer

just take the 2 ends put the together with some tape

324 days and 8 hours ago.

Reply

But the wire is not exposed.

324 days and 8 hours ago.

Reply

Do I have to remove end caps, or put a piece of metal between to make connection?

Answer

ok , do that make sure they dont come apart, if i were u i would jump all the limits out at the same time and see what happens

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Expert: coolman1973
Pos. Feedback: 95.9 %
Accepts: 
Answered: 1/1/2009

Hvac tech and Mechanic

15 yrs field exp/5yrs supervisingexp/ Nate and Epa cert.

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