Rheem furnace won't run in auto

[tmoss]

Unit is 21 years old. In auto when a call for heat occurs, furnace will light then after several minutes shut down on what I presume is the high limit because the blower isn't getting a signal to run. However, if I flip the t-stat fan switch from auto to on before furnace shuts down then the blower runs and I have hot air. T-stat is a 6 year old digital Duracraft with fresh batteries. I've never had a problem with it. A week ago the unit ran fine in AC mode. A cursory inspection by my untrained eyes couldn't find any loose wiring connections at the t-stat or at the furnace. Furnace is burning nice blue flames with no CO in exhaust or airstreams. A tech is coming tomorrow to fix/repair. Any opinions on what is wrong?

[Jultzya]

Welcome to HVAC TALK.

The best thing to do is wait for the tech to show up to diagnose your unit, as it's hard to test the equipment over the net.

At 21 years of age, I wouldn't waste too much money on an expensive repair. You might want to start getting some quotes for a replacement.

(we can't help DIY, due to site rules )

[Swampfox]

What happened jultz, you run out of balloons?

[pecmsg]

I would start getting quotes before it gets much colder

[Jultzya]

Originally posted by swampfox
What happened jultz, you run out of balloons?

Ran out of Helium.

[smokin68]

Sounds like a small,inexpensive repair,so don't condemn it just yet. but like others stated, start saving for a new system. They don't all last 40 years....

[docholiday]

Its likley a small repair as mentioned. They were pretty simple machines back in the day.

[Midwest]

Those weren't 'hot air' baloons, huh? I kind of miss them.
Your messages are right on as usual, and not hot air.

[mister freeze]

it is a pretty simple fix, but get ahold of your nearest American Standard dealer.

[dexman]

Wont likely get 21 years out of American Standard. Better get another RHEEM!!!

[captainrat]

ya right get rheemed, ya will be sorry, American Standard is the best

[tmoss]

Ok if its a simple fix then what is it? Not to worry if you think I'm going to attempt to repair it myself. I have had recent issues with incompetent techs in my area and I'm trying to protect my wallet from dishonest people. I'm out of town for two weeks on business so the repair will take place while I'm gone. I still haven't paid for my 5 month old Trane system and I don't want to waste money on this system (my house has 3) if it truly is unsafe or uneconomic to fix. If its merely an hour or so of tech time to replace a relay or such then I must go that route at this time. I use this site to get accurate advice on probable causes and practical solutions. Thanks for the replies.

[Jultzya]

Originally posted by tmoss
Ok if its a simple fix then what is it? Not to worry if you think I'm going to attempt to repair it myself.

Rules are rules, please respect them.

(we can't help DIY, due to site rules )

[Black Adder]

Sounds like a fan limit control, fairly inexpensive and easy to change.