really odd blower motor problem

[elalbino63]

hi:
strange but it comes on at odd times by itself. I replaced the thermostat it still does it. so i removed the thermostat and with the bare wires sticking out it comes on by itself. stays on for 5 min or so. I had an ac guy look at it but he said he cant do anything unless he is there when it comes on. it comes on sporadically. oddly seems mostly at night. there is a vent by my bed so it blows on me. its a little irritating but its wasting electricity too. first post here and thanks!!!

ps.
Iam on a home repair warranty, $$ bucks per visit,and here is a link to a pic of it.
http://i1194.photobucket.com/albums/...s/DSC01100.jpg

[Texanna Slim]

AirCycler

[elalbino63]

there is no fresh air vent.

[jpsmith1cm]

No pricing permitted.

[cartercrew]

AirCycler

there is no fresh air vent.

Even without a fresh air vent it could be something in the furnace cycling the fan to keep the house air mixed. Some new thermostats are incorporating a Circ mode for the fan, maybe your furnace has something like this built into it.

[elalbino63]

I guess its not as old as I thought. It has a solid state board and is marked on the decal 1993. its really filthy on the inside. should it be blown out with compressed air? the GMC model number is as best as I can read it GMP100-4 Rev 8 or B. The tech the home warranty sent out replaced a part that made the heater come on but said he couldn't do anything about the fan coming on. he wasn't that great he left the drain tube unhooked, the filter half-way in and cut connections inside the unit instead of throwing them away in the trash can right next to it. I guess Ill call the home warranty people on monday. he did get the heater going though. any thoughts?
I also noticed it has 2 fans a small one above maybe to exhaust CO? It and maybe the big lower one comes on when the door in replace and stays on a few minutes. is this normal? if not it may be a way a tech could check it since he said it had to be on when its not supposed to be before he could fix it.

I took some pics of the inside here is a link to the album.
thanks!!!!
http://s1194.photobucket.com/albums/...and%20furnace/

[surenuff]

I guess its not as old as I thought. It has a solid state board and is marked on the decal 1993. its really filthy on the inside. should it be blown out with compressed air? the GMC model number is as best as I can read it GMP100-4 Rev 8 or B. The tech the home warranty sent out replaced a part that made the heater come on but said he couldn't do anything about the fan coming on. he wasn't that great he left the drain tube unhooked, the filter half-way in and cut connections inside the unit instead of throwing them away in the trash can right next to it. I guess Ill call the home warranty people on monday. he did get the heater going though. any thoughts?
I also noticed it has 2 fans a small one above maybe to exhaust CO? It and maybe the big lower one comes on when the door in replace and stays on a few minutes. is this normal? if not it may be a way a tech could check it since he said it had to be on when its not supposed to be before he could fix it.

I took some pics of the inside here is a link to the album.
thanks!!!!
http://s1194.photobucket.com/albums/...and%20furnace/

You said the tech put on a part that made the heater come on but could not do anything about the fan coming on. Was your heater not coming on before?? You original question only mentioned the fan problem. Now as to the fan coming on, it could be a faulty limit that is making contact bringing on the fan, or a faulty relay on the control board sometimes making contact and bringing on the fan, or a t-stat setting or problem. Is there a humidistat or humididty system hooked to this unit?

[dandyme]

me thinks somebody needs to look at that heat exchanger

[surenuff]

me thinks somebody needs to look at that heat exchanger

interesting dandyme, school me on this theory. If you have to, send a pm to me. As far as I could see on the wiring diagram, two relays on the board control blower operation. One for high, and one for low. Like I was thinking, maybe one of the relays, making contact when they should not, or a L/S making contact when it should not triggering a blower relay to come on. But I am interested in the heat exchanger theory. Learn me dandy me, learn me!!!!

[elalbino63]

yes the heater wasn't working as well. I assumed 2 separate problems. That's what the tech said also. Its not important but he showed me the part it looked like some kind of sensor it was very hot and could not pick it up. the thermostat is not currently hooked up and it still does it. Its been pretty mild here in Oklahoma lows in the 50's and highs 80 or so. Haven't been using the unit. we are supposed to get a light freeze this week though. thanks!!

is the blower supposed to come on when the door switch is activated?

[dandyme]

me thinks somebody needs to look at that heat exchanger

where does it state that the hx is the source of fan problem.

personally I think there have been some brain damaged techs on this project, although I have had dealings w/ home warranty personnel

[surenuff]

where does it state that the hx is the source of fan problem.

personally I think there have been some brain damaged techs on this project, although I have had dealings w/ home warranty personnel

I am far from being brain dead. I did not see the pic. In the middle of a discussion about a fan problem, here come a statement from you about looking at the heat heat exchanger. Never heard of anything before with a heat exchanger that could cause a blower problem, but if there was such a thing, I wanted to know about it.