# American Standard 5000 gas furnace



## PyrateJim (Dec 18, 2009)

I have an AS 5000 gas furnace in my home. It is probably close to 15 years old. It has worked flawlessly up until just a few days ago. It will cycle "on" when told to by the thermostat. I can hear it "click" as it begins to cycle, the ignitor will come on, you can see the glow in the heat tubes and then it will click once or twice more and the glow will deminish. It will do this once or twice with the motor running, but the large blower fan in the bottom compartment will not switch on. The red light on the circuit board begins to blink red, but it simply flashes, no code or sequence. The tage on the board states for a "Flashing Red light, refer to your service manual". As the furnace was installed prior to us moving in 10 years ago, there is no service manual. If I turn the power off to the furnace and then immediately turn it back on again (via a "light swtich" on the side of the furnace near the control board) it will cycle/run just fine and heat the house. On occassion, will will cycle several times in a row as it should, before going back into its non-working/blinking mode. 

Does anyone have any ideas what I should be looking at that may be causing this? I am guessing that it is a sensor or switch that has worn out, but I am not sure. The filter is brand new and I have even repalced the thermostat. I would rather not have to spend the $$ on a service call if I dont have to.

Thanks for all the help.


----------



## Houston204 (Oct 18, 2009)

Can you measure for 24VAC to the gas valve when you hear a click after the hot surface ignitor glows?

What is the model number listed inside the burner section of the furnace? 
I may be able to post a manual.

If no trouble code appears with these symptoms, it points to the board.


----------



## PyrateJim (Dec 18, 2009)

Thank Houston, I appreciate all the help I can get.

The furnace is model: TUC100B948AC
The serial number is: F30545736

The light flash's in no sequence. it simply blinks for however long it is allowed to until I reset it either by turning the power on and off at the switch, or by the cover switch for the lower half that houses the blower motor.

I have no way of measuringthe VAC pressure.

Thanks again.


----------



## hvaclover (Oct 2, 2008)

Double check the mod number,

Not working with the number you gave.


----------



## yuri (Nov 29, 2008)

Go to Sears or HDepot, Radio Shack and buy a inexpensive electrical multitester. A good one can be had for under $100. Cheaper than a service call.
Is it a high efficiency furnace with plastic vent pipes or a mid efficiency one with a metal pipe to the chimney?


----------



## Houston204 (Oct 18, 2009)

I couldn't find much on Trane's site with a furnace that age. Looks like an upflow/horizontal condensate furnace.

http://www.trane.com/webcache/un/furnaces (furn)/sales/72-1107-10_05011999.pdf


----------



## PyrateJim (Dec 18, 2009)

For a model number, lets try changing the last character from a "C" to an "0", or TUC100B948A0.

It is a high efficiency furnace with a plastic vent pipe directly out the side of the house.

I'll have a volt tester later this evening and then will have to figure it out.

Here is a pic of the furnace unit if it helps any.

Thanks again.


----------



## beenthere (Oct 11, 2008)

Got gas?


----------



## PyrateJim (Dec 18, 2009)

beenthere said:


> Got gas?


Yes. Issue is with the electrical, be it a sensor or the board.


----------



## beenthere (Oct 11, 2008)

PyrateJim said:


> Yes. Issue is with the electrical, be it a sensor or the board.



How do you know you have gas coming out of the gas valve?


----------



## yuri (Nov 29, 2008)

Do you have a gas water heater or dryer or range and do they work?


----------



## hvaclover (Oct 2, 2008)

am i the only one who knows about the recall on that beast?


----------



## PyrateJim (Dec 18, 2009)

There is gas to the furnace because it heats up and heats the house when I restart it each time. The gas dryer and hot water ank work as well.

What recall?


----------



## prosa (Dec 27, 2010)

Pyratejim , I am having the exact same problem now a year after you , I was wondering if you could tell me what was your out come on this issue , Thank you Prosa


----------



## PyrateJim (Dec 18, 2009)

Turns out mine was nothing more than a dirty, and starting to crack, heat exchanger. Cleaned that up, as well as arond the sensors and pump and all works fine. Had a furnace company come out and recheck and all was good, except the cracked heat exchanger. Tried to sell me a new furnace for $5200.00. So far, furnace is working great this year, no issues and still havent replaced it. When I do, should cost me around $2,000.00, through a different company.


----------



## prosa (Dec 27, 2010)

Thank you were is the unit located? Or what may it look like ?


----------



## PyrateJim (Dec 18, 2009)

The furnace is in our lower utility room. As for the heat exchanger, it is located inside the furnace and I have no pics of it. If you scroll near the top of this thread, you can see a pic of the furnace as a whole.


----------



## prosa (Dec 27, 2010)

Pyratejim , Thank you I do see that pic but not sure if it is the blower motor to the vent or what it may be I tryed looking up on lie but no real direction of were it may be.


----------



## hvaclover (Oct 2, 2008)

PyrateJim said:


> The furnace is in our lower utility room. As for the heat exchanger, it is located inside the furnace and I have no pics of it. If you scroll near the top of this thread, you can see a pic of the furnace as a whole.


I had posted in '09 that there's a recall bulletin on the heat exchanger of your furnace.

By your own admission you know you have a crack in a furnace the factory warned owners about.

Cracks don't get smaller and you cant rely a CO detector to save your life.


----------



## prosa (Dec 27, 2010)

Well after Five hundred bucks, it was a failed gas valve. Two clicks and a tap on it , fired up and need to be replaced.
:furious: for the bill :thumbup:for the Heat !


----------

