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Comfortmaker blower intermittent problem

11K views 12 replies 7 participants last post by  jflag 
#1 ·
I have an 18 year old (1989 SnyderGeneral Model #GUH125A016IN) Comfortmaker furnace that has developed a problem. The blower will stay on at the end of the cycle and continue to blow cold air throughout the house. If I hit the induction fan casing a good “thump” with the heel of my hand, it will cause the blower to stop. The furnace will then usually cycle 2-3 times normally (with the blower shutting off at the end of the cycles) and then the blower will stay on again. If I do nothing, and let the blower run, it will continue to run non-stop through 2-3 heat cycles and then shut itself off normally at the end of one of the heating cycles. It will then function normally again for 2-3 more heating cycles, when it will then stay on again. I suppose my “thumping” on the induction motor is causing a vibration, or jarring somewhere, that resets a stuck switch (?) or some such thing.

At no time does the error light come on during the time the blower continues to run.

I have searched the previous postings for a similar issue, but haven’t found one where you still get heat and the blower stays on, but can be shut off with a “thump”.

Any help, and all suggestions, are greatly appreciated.

John
 
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#2 ·
fan/limit

Its been awhile since I've worked on a Comf. Mkr. Sounds to me the fan/limit may be sticking: Burner comes on and heats an element which in turn closes a switch that energizes the fan. After 'stat is satisfied, burner goes out, the fan continues to run, the heated element cools and is supposed to disengage the fan.
Is there a silver colored box (3"x4") next to the draft motor with 'Honeywell' stamped on it? Or, a smaller black box with wires and terminals exposed--you might read 'Cam-Stat' on it?
 
#3 ·
Thank you very much for the response. You asked "Is there a silver colored box (3"x4") next to the draft motor with 'Honeywell' stamped on it?", yes that is what I have. I removed the cover, and see a dial that has "Fan Limits" on it. I have looked at this before, and wondered if an adjustment there would help, but I am reluctant to "touch things" I don't really understand!

Thank you again, and I look forward to your advice.

John
 
#4 ·
fan/limit

You can try adjusting the "fan" setting: Unplug or disconnect power, press firmly against the large dial and slide the indecator up about 5 degrees, increasing the temp. setting. If you're mechanically inclined you may desire to remove this from the furnace cabinet and sweep it off with a chipper brush and spray with a lubricant (not WD-40). Or if you have access to a parts supplier, you may consider replacing it. I mentioned in another thread that when a major component in the system reaches a certain age, you might look into changing out the appliance.
 
#7 ·
Problem Fixed!

My most sincere thanks to "Undone" for the suggestion as to the Fan Limit Switch being the culprit. It was. I found a supplier, Erb Co. of Buffalo, NY, who took the time to locate a suitable replacement Honeywell Fan & Limit Control (L4064 B 2236) and then explain a few things to me about installing it. The cost was $58 + tax. Everything is running smoothly and back to normal.

Thanks again,
John
 
#8 ·
Merry Christmas

It brings me a certain degree of satisfaction knowing your furnace is back in operation.
When given the opportunity to assist someone in need--well, let's just say it is meant to be.
And so, with this 'favor', if you will, pass on the true meaning of this season--Give to someone in need and it too will return to you.
Thanx for letting me be of assistance. And again, have the most blessed Christmas of all!

John (aka, undone)
 
#9 ·
Hey undone

I read your excellent comments to jh44ny about the fan/limit sticking. I have a Comf mkr and mine is sticking too. I removed it and saw no real serviceability. I appears that the affixed coiled metal screw that goes into the heat exchanged does not have enough tension in it to properly kick the switch to turn the fan off after it cools. I figured this out as I watched the dial return to cold position and the fan just kept running. I put a nail in one of the holes in the face plate of the dial and moved it counter clockwise thinking it did not have enough return travel. Nothing. Then I wound it 90 degree left and let it go and the spring action had the kick to shut the fan off. I am going to order a new part as at 17 years it owes me nothing. But the mechanic in me wants to know how this thing works? Does the metal fatigue and lose its ability to kick. Am I correct that it has to kick? Is this part serviceable? How would you lubricate it? Is there an adjustment that would fix this problem.
 
#10 ·
The metal does fatigue over time and loose it's spring tension. I don't know if I would call it a 'kick', it merely mechanically opens the switch. After 17 years of service for you, it's time for a replacement part. It's not serviceable that I know of.
 
#11 ·
I have a Comfortmaker GUH100, I have replaced flame sensors, limit switchs and ignitors over the years, as i recall the 3 blink open pressure switch indicator often came on. This year the ignition sequence will not throw power to the ignitor, I have tested the ignitor and it works, I have tried to start it with the with limit and pressure switch jumpered to the go ahead postions for the control board to turn the ignitor on but it does not do it, a repalcement board is about $100. in 2005 i repalced the draft motor. I am at my wits end with this furnace!
 
#12 ·
i have a 1989 comfortmaker I changed the blower motor andt the sensor, the thermostat and the run compactor I got it to work for a day but it went off again I get 24 volts from the themostat but the outside unit or the blower motor will not come on. I put a jumper from the themostat screw directly to the out side both work find but will not cut off. help
 
#13 · (Edited)
i have a 1989 comfortmaker I changed the blower motor andt the sensor, the thermostat and the run compactor I got it to work for a day but it went off again I get 24 volts from the thermostat but the outside unit or the blower motor will not come on. I put a jumper from the themostat screw directly to the out side both work find but will not cut off. help
Is this just a air handler or does it also have a furnace, how long have you had this system? which sensor? Do you mean run capacitor? If I recall there are a total of 3 (safety) switchs related to furnace function that will cause the controller to lock out. The fact that it worked for a day is strange, is there moisture building or backing up somewhere? What does the controller board flashing LED code read? pics of your wiring may also help, Is the wire to the outside unit new? and is it heavy enough gauge? Can you test the capacitor?
 
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