[kenman65]

Hello,

I have a Carrier Wethermaker 8000 gas furnace. Over the past week or so, I've noticed that the temperature in my house drops into the low 60's (I usually keep the thermostat on 68/69) and the furnace never kicks on. The thrmostat itself seems to be OK. The problem is intermittent at this point.

When this problems occurs, I go to the furnace and toggle the on/off switch to the transformer, the furnace will then fire up and run fine. My first thought is that I've got a flakey transformer. Any thoughts?

Thanks,
Ken

[kewasiuk]

Hi there
Did you ever get an answer for your problem? I have the same issue with no answer?
Kyle

[juggallojed]

Read the faq section, In this case I'm thinking the flame sencor may be dirty.

But I'm not there so its just a guess.

[cirquo]

Hi there
Did you ever get an answer for your problem? I have the same issue with no answer?
Kyle

Did this resolve your issue. I seem to have a similar problem. The on/off switch doesn't restart it anymore, it used to. Now I have to take the bottom and top covers off which resets the furnace and then runs fine for a day until it I have to take the covers off again. I wonder if the flame sensor needs to be cleaned as well or it's something else.

[kenman65]

Hi Kyle,

I'm not sure if someone from this site answered it or not. But here's what I did to fix it:

1. Take off the upper cover on the furnace to access the burner unit. (Mine has four burners).

2. On the leftmost burner, you should see what looks like a wire protruding on the far side. (From what I understand, this is some type of heat sensor).

3. Run a piece of emory cloth or sanpaper over it a few times. This will knock off any dust or contamination that may have accumalted.

4. Also, make sure you have clean air filter insatled.

This worked for me, hopefully you'll have the same result.

Good luck,
Ken

[kenman65]

Oops, I should give credit where credit is due...

Jugallojed came up with the fix... :-)

[NorthernHeat]

Hi there
Did you ever get an answer for your problem? I have the same issue with no answer?
Kyle

When you need to reset the furnace and it starts again it is a safety feature in the circuit board. If the furnace fails to run like it should, the circuit board does what's known as a lock out. There should be a window in front of the PC board. In the window there is a red LED that will flash a code when it is locked out. Say the code is 2 short flashes followed by 2 long flashes. Look at the legend on the blower door and it will tell you why it locked out. Best of luck.

[cirquo]

I located the LED, the codes on the cover, no flashes of codes, the furnace was off for a bit when I got there. I had the same HVAC friend come by and take he said something about overlimit heat.

[cirquo]

I think the code for overlimit is 34. I didn't see it myself on the LED. I know, frustratubg.

[bgior]

I just joined and have the same problem with a Carrier 58SXC080 furnace. The furnace was installed in 1992. The combustion blower failed under warranty the first season. The PC board failed and was replaced about 5 years later.
From what I can tell when it fails now the hot surface ignitor heats up but the gas valve doesn't open. Ignitor power is cut but there is no flame. It cycles through 3 attempts to get a fire going by powering up the hot surface ignitor. After the third failure it shuts down and locks out. Power-cycling the furnace switch (off-on) causes it to run a brief purge with the blower, then run the combustion chamber blower, then attempt another ignition. It will usually start then but at the next call for heat I often have the same problem. I replaced the flame sensor even though the symptom doesn't fit a flame sensor failure. I also replaced the thermostat.
I'm about to buy a replacement PC board. This will be my second and I paid over $400 for the first replacement by the HVAC company that installed the furnace. I found an on-line supplier for under $200.

[thezel]

Thanks for the help in this, I asked a friend he stated to pull the sensor out removing one screw and disconnecting one wire. Clean the sensor with steel wool. It has been a couple of days and it is working. He stated the sensor is there to ensure all burners light if it is dirty it will cause the error shutting down for 3 hours. Thanks again for the help in figuring this out.

[lukez]

I have been having this same probem with the same furnace model. I limped through last winter just throwing the on/off and it might be fine for weeks or only for a day. It is now doing it again. Had it serviced a few times last year with no luck. Just had a service tech tell me it is a known problem with this model and there was a part you could buy specifically for this issue on this furnace but it is now discontinued.

[trini2012]

Hello,

I had a similar issue with intermittent operation on a Carrier Weathermaker Infinity. We went through all of the above steps with checking the flame sensor but had no luck. We finally decided we would disconnect the hose to the heat exchanger and we noticed that there was a build up of a small amount of water in the heat exchanger causing the furnace to shut off prematurely. Took out the hose and blew it out. Reconnected the hose and furnace started up like a charm! The water had accumulated due to a malfunctioning water pump motor that was attached to the furnace to expedite the flow of moisture out.

Hope this helps!

[Stingray65]

Check the fleu pipe for any obstructions, I found three dead small birds in mine.
Once cleaned it operate great now