After many trouble codes, I have finally been able to get my furnace to fire and stay lit. Only problem is that now the air coming out of my vents is about 65 degrees F. My house is 58 degrees and it is below 0 outside, so it won't be long before this furnace is completely outweighed by the cold. How can I get the fire to be hotter? Should I adjust the fan speed as well? The house is a 2 story plus basement, about 4000 sqft if that helps. Thanks

Me not knowing what kind of furnace you have I will just have to guess at what I should tell you. Since you said that about the codes I assmue that it is a fairly new furnace so that is what I will tell you about.
You have two different speed terminals on your circuit board, you could make sure that you heat terminal is connected to the slowest motor speed wire coming out of the motor. There again I am assuming that you have a multi speed motor.

Another thing that could affect the air entering the house is where your return air gets it air. Also if the furnace is the garage or the attic, it could be that you have a leak and extremely cold air is getting into your return air duct.

Speaking of return duct,, when the last time you changed the filter?

LP? Perhaps a problem with the tank regulator...

It's a York 90+ HE. Just installed 2 days ago, its about a 4 yr old unit. Now I've been able to get the heat up, but now it seems like it's a little too hot because I keep getting the high limit error, which kicks out the burners until the fans bring it back down. I have the fan on the blue wire (4 speed) for heat, and black wire for A/C. I have tried the other speeds and its so slow that it can't push the air through the house. I replace a 133,000BTU old style furnace that had no problems with supply or return. Ran rather well and got my vents very hot.

Forgot to also mention its natural gas.

You installed a used furnace? The blower runs slow? Eek... now you tell us...

The blower runs slow when its on slow, it needs to be on medium or higher to push air through my miles of ducting. Furnace is used, but not really. It was installed 3 years ago and never used. Guy had some money and put this unit in his 800 sqft. Garage. Is there anyway to keep it from hitting the high limit issue (4 lights)? I have been able to correct just about everything else. Thanks

High limit action indicates the furnace is overheating, usually due to inadequate airflow. Decreasing the blower speed will further complicate this issue. If this unit was not experiencing this problem in its previous location, it is likely that your duct system is undersized for this unit.

The gas pressure regulator at the gas valve needs to be properly adjusted and the orifice checked for the proper natural gas one.

That is correct, at least so far. I have now been able to keep the furnace and all components running for about 20 min, air vent temp is about 110 degrees F. Big notes of change, blower is on second to highest level and the air filter has been removed. The air filter was not what I would call dirty, but I believe it just doesn't have enough return. I have left the basement door open and I can feel the cold air being pulled down the stairways... good stuff, especially with outdoor temperatures at artic levels. Thanks for the help.

KC13 was correct. I removed the air filter (which was clean) and it has worked since. Air vent temp is about 110 degree F. It would seem I do not have enough return for this new furnace, so I have begun putting some in. Thanks for the help gentlemen.

I vote for the undersized ductwork/ but could be that the furnace is to big for the ductwork:)

Another case of trying to save some money actually costing you more in the long run. You cannot simply change out a furnace without doing the appropriate calculations.

This thing ran most of the night with KC13's comments. I opened everything up as much as possible and it worked great, I even got hot last night. Now, its 8AM, and its 51 degrees in my house. I get the 3 lights of death, and I cannot get around it. I have blown through the tubes, the sensor, bypassed the sensor, tried everything I can think... and no fire!! Help, I am freezing.

You have played with every control and device on the unit and at this point I recommend you call for a On Site professional so they can sort it out correctly. Lucky for you that unit has all the built in safety features or this could have been a disaster.

How big is the area that you are trying to heat now? And how many registers do you have? What size is your return air duct? Also did you decrease the size of the plenum coming off the top of the furnace. All of these things can affect the limit switch.

I think I have gotten things under control. As I said for last night, it cycled as it should. This morning is when I found out it the pressure switch was stuck open. Usually I can blow through it and it will kick on. But, I tapped it and it released, everything is again hunkydoory. So, I replaced the switch. I also used a gas meter to make sure my manifold pressure is correct, and the door says a pressure of 3.5 in. I had it at 5, so that is why I could see the high temp sensor error. Now, it has been running for hours, but I am not convinced that the duct work is in good shape for this furnace. I have some returns sucking serious air while others aren't event causing a paper to flap. So, I think the next logical step is to look for obstructions, tinker with fan speed, etc. But to answer your questions: the house is about 3800 sqft; 18 supply vents, 10 returns (a couple are doubles); the duct running into the furnace is 20x15; the supply is the same as the last furnace (rather large); 2 vents right above furnace are quit hot, but others (maybe 15-20 ft away) are not near as hot.