# american standard freedom 90 just blows cold air



## techpappy (Jul 8, 2012)

not that familiar with latest equipment but, look for a reset button near burners and reset OR just turn power off and back on then see what happens.."thermal" switch open seems like might be due to lack of air flow causing heat exchanger to overheat....could be dirty filters, "A" coil, furnace fan etc., OR defective control or thermal switch..thermal sensor looks like silver? button on front of unit with two wires going to it....

Check filters, A Coil to make sure they are clean and clean if neccessary before anything else


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## techpappy (Jul 8, 2012)

may also be induced air fan OR ventor motor or air flow sensing lines ..if so equipped...induced draft motor should run as soon as stat calls for heat..this creates air flow for exhaust..the air flow must be proven by the air flow switch..( looks like small diaphragm with wires and tubes going to it..Disconnect tubes and blow/suck on each one ..should hear switch clicking on and off...Once air flow is proven the ignition glow coil OR spark igniter should come on and light the gas pilot..Once the gas pilot is proven then the main gas valve will be energized and open main gas to burner,,then, once the heat exchanger warms up the circulating fan then, comes on to circulate warm air


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## danpik (Sep 11, 2011)

If the blower fan is running whenever the power is on to the furnace then I would suspect a bad High Limit Switch. 

This may be the type in your furnace...










What you would see is the black side with the two wire terminals on it. This is one of several "thermal protection devices" on the furnace. When this type goes bad the fan usually comes on and stays on. 

There may also be one or more Rollout Switches around or near the burners. These devices are sometimes resetable depending on the type.

This style...










shown from the back side has a small push button in the center to reset it. The front side looks like a small 1/2" button.


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## beenthere (Oct 11, 2008)

Check your air filter. It may be dirty and causing the furnace to go out on high limit or aux limit.


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## techpappy (Jul 8, 2012)

Right ON! Now I know more important information. Good Stuff!!


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## lamarch77 (Sep 25, 2012)

Ok I opened up the freedom 90 to try and find the filter ( just bought the house a few months back) could not find it any where. I m I just blind? heres what it looks like.


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## lamarch77 (Sep 25, 2012)

*moving on*

ok so I cant find the filter like I said so I thought I'll look for things that you all showed me ...this is what I found ( I found the circle with two yellow wires coming from it with a reset switch in the middle, I could not get it to push it and stay in) Then I came to the wire thing by the burners which looks bad I tried to clean with steel wool......the tip just broke off :whistling2:


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## lamarch77 (Sep 25, 2012)

ok now I think I may need those two part replaced right ? be for the heck of it just in case thats no it I'll post closes ups of the in side of the cold hearted beast. I would also like to say thank you to all who replyed and shared the knowledge:thumbup:


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## techpappy (Jul 8, 2012)

That flame sensor is called a flame rod and should definitely be replaced. 

The filter is in the back of the unit where the circulating fan motor is. Sometimes accessed at side of unit as well. You will likely have to remove the access door at the back to get to the filter..OR there may be a slot in the side of the furnace where you can access the filter to pull it out.


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## lamarch77 (Sep 25, 2012)

there is no way to get to the back it is in a little closet that picture shows the whole room.


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## techpappy (Jul 8, 2012)

Then it is installed wrong. You need access to change filter, service/replace circulating fan, check for cracked heat exchanger etc.

OR

Is there possibly an access from top or bottom of the unit. Maybe in basement/crawlspace.


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## lamarch77 (Sep 25, 2012)

a crawl space


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## lamarch77 (Sep 25, 2012)

i never thought that there would be parts of it down there, thank you


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## danpik (Sep 11, 2011)

lamarch77 said:


> ok so I cant find the filter like I said so I thought I'll look for things that you all showed me ...this is what I found ( I found the circle with two yellow wires coming from it with a reset switch in the middle, I could not get it to push it and stay in) Then I came to the wire thing by the burners which looks bad I tried to clean with steel wool......the tip just broke off :whistling2:


Ok, the rollout switch can be tested with a continuity meter. The little button on the back looks to be in the normal position. Push in on the front of it. If you hear it "snap" then you just tripped it. Pushing the putton on the back will then reset it. 

The flame sensor as mentioned needs to be replaced. How that furnace stayed lit with a rod like that is beyond me. They need to be as clean or cleaner than the part near the ceramic to work properly.

As far as the filter...Wherever the cold air return duct comes back to the furnace is is where the filter "should" be located. If it is not there then follow the return back along the length and see if there is a location where one may slide in. Also look in the cold air return vents and see if they put one there. I have seen it in the past.


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## danpik (Sep 11, 2011)

Also , please clarify for us...

Does the furnace light or try to light?

Does the inducer fan turn on? (small round black housing in the front hooked to the exaust pipe)

Is the blower running all the time like indicated in the title? (cold air out the heat vents)


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## lamarch77 (Sep 25, 2012)

this place is great and filled with very helpful and wise people thank you so much for teaching me a good life skill:thumbsup:


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## lamarch77 (Sep 25, 2012)

It does not try to light, I dont see any thing glowing or sparks where I use to see flames. The fan does kick on right away


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## techpappy (Jul 8, 2012)

definitely replace those parts then continue with the following

1. Once induced draft fan comes on, this causes a differential air pressure in the flue which s activates the "air flow/pressure" switch when that happens a circuit is made to allow for the pilot to come on ..once pilot is established then the "flame rod" proves there is a source for ignition and sends power to the main valve to open gas to the burners... voila!! It's working..NO?..get back to us. Good Luck!!


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## lamarch77 (Sep 25, 2012)

thank you , I can wait to try it all out and see if it works, If it does I fixed my own furance Wow this is kinda fun. I will let you all know what happens I hope to seee this from my furance :furious:


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## lamarch77 (Sep 25, 2012)

to keep all you great people up to date, I replaced both those parts that I took pictures of ( still getting the 4 light flash) I'm sure Its the filter. Who knows when its beeb changed . I plan on crawling under the house this weekend and try to find this filter, I'll let you all know what happens next.....Thank you all soooo much


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## techpappy (Jul 8, 2012)

So what exactly is happening...IF Nothing, then it is not the filter. That would only come into play if the furnace ran for a while then locked out due to over temp which could be due to system air flow problems/plugged filter etc.

Does the ID fan come on..if so, then what..describe and we will go from there.

I think you found your filters and by the looks of your pics there isn't any duct work below the furnace so, no filters in crawl space. But then pics are not all inclusive but don't be discouraged if you do not find filters there.

Turn power off to furnace at furnace switch then .turn stat up ..turn 

furnace switch ON and observe sequencing, if any...Get back to us


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## how (Feb 26, 2011)

Your first photo shows a furnace configured in a down flow position. The only practical position to install a filter would be..

in the crawlspace *only* if your return air duct loops back on itself and goes down behind the furnace into the crawl space. (hate crawl spaces)

*In the ducting above the furnace but a filter access door would have been visable.
*Inside the fan compartment just above the fan but is unlikely as it would be too awkward to regularly service.
*Behind the house return air grill.(especially if you only have one)

This down flow configuration also means there is probably another limit switch inside that fan compartment. Usually 2 of the same sized wires that connected to your other limit will be seen going into the fan compartment as well. 
If so, it will involve shutting off your power and opening up that upper fan compartment door to track them to that fan compartment limit. 
That will also give you a chance to view above that fan to see if there is a filter there.

You also have heavy water staining below your inducer motor (probably from leaking condensate) which you should check out once the furnace is running again.


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