Coleman Evcon 7900 Presidential III Blower Problem

[GrizzlyBear]

I have a Coleman Evcon 7900 series Presidential III Direct vent forced air gas furnace model #7970C856. I just bought this place last September and the furnace ran good last winter. When we fired up the furnace this year we immediately knew we had a problem.

When we turn up the Thermostat the furnace kicks on and about a min or so later the blower will kick on. Then after a few mins the blower will kick off but the house will not be up to temperature yet. It will continue to kick on and off at different intervals every time it runs. I think it is a blower relay but looking for some expert help to give me some insite. Any help would be greatly appreciated.

Thanks in advance,

Sean

[hvac1000]

Your main burner orifice could be partially restricted causing the unit to not be able to stay on because the flame does not get hot enough. This will cause the blower to cycle on the fan control thermostat.

Could be the blower fan motor getting to hot. Next time it runs and stops turn off the power and feel the motor. It should be warm but not hot.

It could be a defective blower fan control.

[w_iked]

I am Having the same problem what did you do to fix the problem HVAC rapair is quite expensive thanks

[Robert]

Hi w_iked,

Please start a new thread with your question and then delete this post.


This keeps down confusion with more than one problem in one thread.

It could be any of the answers given.


Keep in mind, the same symptom could be due to different reasons.


If inexperienced in working with a gas furnace, it is best to call a Tech.


Thanks,
Robert

[GrizzlyBear]

So we called someone out to work on the furnace and they said it was a bad fan switch. They came back the next day and replaced it and the blower still kicks on and off at iregular patterns even though the burner is still running. He told me that the A coil in the bottom of the furnace needed cleaned.

We called them back a second time to look at the furnace and he told my wife that A coil still needed cleaning. I hadn't gotten to it yet. So we partially cleaned it and told her that I needed to clean it more. Then then also supposively told my wife that the blower is not staying running because it is getting to hot in the furnace.

I tried what you told me HVAC1000. Once the furnace ran once and then shut off I turned the power off to the furnace and felt the blower motor. It was warm but not hot. I could hold my entire hand on it for a long time.

I just wanted to know if anyone could give me some info on if the A coil was dirty if that would affect the blower running or not. I thought that the A coil had to do with the A/C. I also thought that if the chamber was getting to hot that the blower would run longer not shorter like that furnace people said. Any Help would be greatly appreciated. Thanks in advance.

Sean

[hvac1000]

Your blower motor is OK if you can put your hand on it for awhile.

The air from the furnace blower has to pass thru the A coil in order to leave the furnace. If the A coil is dirty it will cause many problems and one of them is exactly what you have right now. The coil sometimes needs to be removed to clean. That is best left to a pro because you have to recover the refrigerant block off the lines clean the coil then reinstall and recharge the system.

Sometimes you can get to the coil and use a brush to remover the mat that is covering it but that does not clean the parts of the coil that are deep inside.

We always preach keep the furnace filters clean trying to prevent the problem you have now.

[Robert]

This may help with cleaning the a-coil:

http://www.mobilehomerepair.com/article ... ioner.html



Take care and best wishes,
Robert

[glennasrick]

Can someone explain to me how I light the pilot light??? I've never used this type of furnace (moved in during the summer) and I have about 40% of my propane left. I'm just trying to get it lit so that I can use the propane I have now before getting it filled.

[Robert]

Hi,

Please start a new thread with your question and furnace model

number. Then return here and delete your post here.


Thanks,
Robert