I have a Carrier 58STA, starts up and runs fine, but the burners only stay on for between 5 to 10 minutes, then the burners turn off and it stops making heat, it blows cold air for about 3 minutes after the burners shut off. It flashes the code #33 until the blower stops, then it starts over again. It never stays going long enough to heat up the house. Please let me know if you have any ideas of what could be going on. Thank you.

The Carrier 3-3 diagnostic code indicates that the furnace is overheating and shutting off on the limit switch. The fan continues to run until the furnace cools off then the burners light again and the cycle repeats.

The most commonj reason for this is a plugged furnace filter that needs to be replaced. Then check to see that the return air grill that sucks air in is unobstructed and that thwe warm air vents are no closed or blocked. Check those things and report back.

SeattlePioneer, When it first started yesterday, my first thought was the filter, so I did replace that, there are three intake vents, two are in the house and one is outside, but the one outside is like the dryer vent type it is closed and would only open if air blew out... when it is running if I go an open the slots it does have a good amount of suction, but it has always been like that. All of the house vents are open. It's only 65 degrees in the house we are in Minnesota so it is very cold outside. What should I do next?

Check to see if the fan turns freely hen turned by hand, or if it is stiff and has significant resistance to turning.

Does the fan start easily and appear to come up to speed promptly?

Is the fan wheel saturated with dust, dirt or debris which would impair its efficiency? If so the fan assembly will need to be removed and completely disassembled to clean it properly.

Does the fan run continuously, or does it just stop sometime while the furnace is hot? (the fan motor will shut off on a thermal limit switch if it overheats)

Do you have central air conditioning with an AC coil in the furnace duct work? They are prone to becoming plugged with dust, dirt and debris, especially if the furnace is run without a filter. The side of the AC coil next to the furnace needs to be carefully inspected for plugging and cleaned if needed. This can be a difficult job.

Ok. I don't see any fan. The only thing I took apart was the big main cover. I have not removed the cover that covers the LED yet.

I did notice that the exhaust vent gets really hot there is also some type of sensor on that as well.

When you say fan do you mean blower motor? It sounds like it fires right up and it blows pretty well out of the vents. The fan runs even after the burners turn off, it runs for approximately 3 minutes after then after that it stops, and it starts over again.

I do have central air, I am assuming I would have an AC coil in there. I have attached a picture of my furnace. I really appreciate the help I will wait to see how to proceed.

The fan is behind the lower door with the viewing port in it.

Check the fan motor and fan wheel for debris. If they are dirty the AC coil is probably dirty too.

The AC coil is located above the furnace and has a tube draining condensate from the coil visible in your picture.

Ok, I am going to investigate the fan motor and wheel as well as the AC coil. I will report my findings in about the next 20 minutes.

33 LIMIT CIRCUIT FAULT - Indicates a limit, draft safeguard, flame rollout, or blocked vent
Switch (if used) is open. Blower will run for 4 minutes or until open switch remakes
Whichever is longer. If open longer than 3 minutes, code changes to lockout #13.
If open less than 3 minutes status code #33 continues to flash until blower shuts off.
Flame rollout switch and BVSS require manual reset. Check for: - Restricted vent
- Proper vent sizing - Loose blower wheel. - Excessive wind
- Dirty filter or restricted duct system.
- Defective blower motor or capacitor. - Defective switch or connections.
- Inadequate combustion air supply (Flame Roll-out Switch open).

Yes, but you need to check the things mentioned in my last post.

Sorry for not getting back for so long but it took me a while to get the cover for the ac coil off. The coil was actually surprisingly shiny looking.

The Blower Wheel (turbine) had minimal dust on it, it rolled really smoothly and easily, spun for a long time nice and straight with just a little push.

The Motor did have a fair amount of dust build up on the back but it was strong and steady, I vacced the dust off.

I powered it back on it it actually ran for 20 minutes which is double what it ran in the last two days.. but it still shut off and flashed 33.

The outside of the inducer that spins around is kind of hard to spin by had it doesn't move freely and when it first starts up it squeals a bit.

What is the best way to tell if it is the switches?

Should my furnace have an air intake that goes outside that is open? It has that one but its always closed...

You checked the side of the A/C coil that is on the same side as the furnace I presume?

Basically, you need to check the duct work from one end to the other. Sometimes you can have duct work that is insulated and the insulation has come loose and plugged up the duct work, or collapsed duct someplace.

There is a high probability that something is plugging up the system. You need to identify what that is and correct it.

A GOOD furnace repairman would drill some holes and take pressure reading in the ductwork to identify the static pressure at various points which would disclose whether and where there was a problem. That would be the scientific method.

Absent that, you have to hunt around the hard way, although when you find something it will probably be pretty obvious.

Sorry I can't be more help. I've pointed out the typical things that are a problem.

I really do appreciate the help, Thank you. The temperature is actually starting to go up in the house now... It seems to run for a bit longer now.

Very likely something is pluggin up the air flow through the furnace and causing the furnace to over heat. You need to identify what that is and correct it.

Once that is done you probably need to replace the inducer motor, which is apparently getting ready to fail because the motor bearings are failing and it's hard to turn.

Also, I imagine that the fan motor hasn't been oiled in years. That can fail and be an expensive bill, or you can remove and diassemble the fan assembly and oil both oil ports and the motor will probably ooperate for additional years without a problem.