glennjanie

Hello John:
AAHHHHAA! so the plot thickens. I think you are narrowing the problem down. I hope it works out soon; its 21* here tonight.
Glenn

johnceberhardt

Hi Glenn,
It not only thickens but it freezes! I didn't get to it yesterday (work gets in the way) but the back half of the house maintained 63* all night despite the 6* temp outside. The old york kicked on and off all night long. Tonight we'll be lucky if it stays above zero. Right now it's a balmy 24 with snow showers and winds gusting to over 30. Wish I was in Kentucky...
Even if I can isolate the problem today or tomorrow, I won't be able to get parts til Monday at the earliest-yahoo!
John

johnceberhardt

During normal operations I only measured 70 volts at the black wire relay connection when activated (this is a 115-120 volt blower, right?). I connected the black wire up to 120 volts straight into a socket using a plug wire set and the blower seemed to work fine (it didn’t blow up or anything and seemed to be blowing fine). Therefore, I jumpered across the relay so the black (hi-speed) would be at 120V all the time (same as when the fan is set from “auto” to “on”). The ignition controller did not like the fact that the chamber was so cool and would not keep the igniter wire hot. It would shut down and the gas and the burner would never light. Now I understand why the house was a lot cooler when I'd leave the fan running all night, I’ve never seen it do that before. So I connected that the black wire up to where the blue wire was connected and let it run. It seems to take a longer to shut down but it still trips the high limit switch. So here's where I'm at:
If I leave the blower run “on” all of the time it will ignite the burner about half of the time or less.
If I leave it hooked up the way it was originally, it seems to run the blower for a few minutes before the upper limit switch is tripped.
If I connect the black wire to where the blue wire was and leave the blue a wire disconnected it seems to run a little bit longer but the upper limit switch is still tripped. It will not stay running until the thermostat tells it to stop. I can’t tell if the blower is blowing hard enough but it does not seem to be. There are no obstructions that would explain the lack of blower power or air volume output. So either the fan limit switch is not reading the temperature correctly or the blower is not running up to speed.

glennjanie

Hello John:
It looks like we're back to the limit switch. I don't understand why it will not fire up with the fan running. I'm baffled if the limit switch doesn't do the trick.
Glenn

johnceberhardt

I know it doesn't make any sense. Right now its relays are kicking off and on almost at random (very cold outside) , sometimes ignites and sometimes not. It will run for only a minute at a time- getting worse. When it does run ands gets the flame lit, it shuts down right when the blower relay kicks in. I'll take a look at it and report more in a little bit.

I downloaded the White Rodgers HSI control module troubelshooting guide. What a worthless flowchart!

I've included the schematic but had to break it up becasue of size constraints.

I have to go to Milwaukee for a week so I won't get back to it til next Tuesday or Wednesday

John

johnceberhardt

Here is the latest strange thing that explains the latest twist of randomness. The vent motor was overheating and shutting the system down. It never got a chance to cool off because it never gets a break. I have a fan on it now and it is back to "normal" fail mode. At least this was logical.

Is the vent motor rated for constant running?

John

bacardi547

John:
I have a question for you? I see none of the obvious restrictions to air flow are present but did you look at the "squirel cage" ,the actual fan blades? They should be cupped and it is possable that after years of corosion and dirt (especialy when there is water acting to solidify or corode) the pitch may not be enough to move enough air to cool down the heat exchanger properly. One more idea that is more likley is with p.s.c. motors sometimes the run capacitors do not put out enough uf or microfarads , being that they are only about 10 bucks a pop i would replace it if you dont have a capacitance tester. to your eye the fan may appear to run at full speed but the limit switch is telling us diffrent. Hope that helps.
Brian

johnceberhardt

Hi Brian,

I appreciate the advice. That is possible since I have not yet pulled apart the entire blower assembly. I will rip it apart next week and let you know. I have a cap tester but haven't used it since most caps in the past have blown open or shorted out (and catastrophe for some other part near by follows).

John

briambran

John,
Found this site by accident tonight. My problem mirrors yours. The York fires, and after 5 minutes shuts down. Do you hear a gurgling sound after yours shuts off? I did. Traced it and realized the drain trap that is screwed to the big blower fan (squirrel cage??) was completely clogged. You posted a picture of this drain trap. By chance did you check it for a clog? I cleaned mine out, and PRESTO! No problems now. I am a complete noob when it comes to HVAC...got real lucky I guess.

Regards,
Brian

johnceberhardt

You mean your furnace caught a "cold" and had drainage problems? -WOW!

I never noticed a gurgle but that doesn't mean it's not the problem. I had the thing off when I disassembled and cleaned up all the parts near the blower but never checked that for a clog. I had a carrier that shut down years ago due to a clogged hose. It was like salt in a cooking show--just a little pinch will do it.

I hope that's it for me too but I'm not sure. This furnace is not an Einstein. It has no smarts at all. It's funny, I have another carrier weathermaker (I don't think they make that one anymore) running the front half of this house just like my old one and this is one smart machine when compared to my simpleton york.

I'll be looking at it tomorrow or some days thereafter. Man is it cold here!!!! And now the snow is coming again.....I'll let you know.

Thanks Brian!

John