wrote in message
ups.com...
My furnace just blows cold air. I checked on thermostat. There is
nothing wrong. I took off the panel on furnace and pushed white button.
The two green Led Indication Lights are on with(DS1-- Slow flash, a
flash/per second, DS2--on). According to the label on the panel it
means "primary/secondary limit switch open". I have no clue what it
means and what the problem is. I notice there is no gas coming out and
the electronic ignition does not turn red. But It blows cold air.

My furnace model is Lennox Merit Series G40UH-69D-155-01. It was
installed Apr. 2001.

Here are my questions.
1) What is the possible problem?

One of the limit switches is open.

2) What does "primary/secondary limit switch open" mean?

Means something got too hot.

3) Is it still under warranty? The Lennox website says "5-Year Limited
Warranty on covered components."


Well, IF the switch is bad, yes, if its not, no.
Have to ask...when was the last time you got it serviced? If its been a
while, its telling you something.

Also, Lennox is one of the WORST for bad boards. The Surelight board in
particular. White Rodgers really screwed the pootch with those...I have one
that got replaced today as a matter of fact sitting here for a warranty
card...
Looks fine on the front...roll it over and its a mess. 24V side, the side
that your limits are on, looks like someone took a torch to it..and
amazingly enough, it still threw a code.

I can make a suggestion, but anything you do is at your own risk, since if
it IS an open limit, and you reset it, and there is a reason it
tripped..they dont just trip...
What you are looking for is a dime sized disk, with two orange wires to
it..you should have two..one near the burner assembly and one over at the
blower somewhere..depending on your serial number, you might have up to 3
around the burner assembly.
There will be a red button on at least one of them. With the POWER OFF, you
can press each one in slightly, and if you hear one go CLICK, check the
rest, and retry the furnace.
If it still does not fire up, DO NOT EVEN THINK about bypassing one..you
bypass one, have an overfire condition, its overheating the unit, and your
home burns down....well, guess what? The furnace will be one of the first
things they check and the fire marshal can tell you bypassed it...and badda
bing...you or someone in the home might be dead, and you got no insurance...
If you cant find it, dont feel safe doing this, or just dont want to, CALL
AN INSURED TECH out...if he ****s something up, you are covered. Expect to
pay even if its under warranty. Warranty parts are covered, labor is not.
If its the board, and its a POS SureLight, let them find it, cover it, and
even with labor, you come out much cheaper.

I also strongly suggest that if you DO find a limit tripped, that you STILL
get a company out there, because I cant stat it enough..those are one of the
first lines of warning you get...they are there for a reason. FIND OUT WHY
IT TRIPPED.
Believe it or not, those parts in the furnace dont talk about you all night
and take suggestions from other parts..
hey man...lets freeze this asshole today....OK...who is gonna trip first?
Ya know?

If you havent had it serviced since you got it, shame on the installers, and
shame on you. This might be what we call a nusance trip that could have been
prevented with a simple service.


Thanks in Advance.
Shiling