Gas and Oil Home Heating Furnaces - Tempstar Fan blower keeps running

I have a Tempstar Model no: CGJ100N04 (about 15 years old). I have the T-stat swiched to cool and the fan blower runs all the time. It seems that it is being powered by the fan timer, since I hear the blower relay (and verify with a voltmeter) working properly. The t-stat is swiched to fan auto. I am confused as to why the blower timer is even involved in the cooling circuit, I thought that was strickly for heating.

Any ideas?

Thanks in advance

If you have a standing pilot in the furnace . This can make the blower run sometimes off the fan control. Might check

it is a Hi-efficeincy furnace with no standing pilot. It has a weird fan timer/control with a fan on and off timer. I think this may be the cause of my problem.

it is a Hi-efficeincy furnace with no standing pilot. It has a weird fan timer/control with a fan on and off timer. I think this may be the cause of my problem.

Did they have fancontrol boards 15 years ago? I have worked on Tempstars of that vintage.


Are you sure this "timer" you think you see is really not a Honeywell fan switch? They are mounted on the inside of the furnace above the burner compartment, and are aluminum color and about 2 1/2 inches wide x 2 inches deep and 4 inches? long and have a dial inside, - but the dial is not a timer - it is a temperature dial and when the dial rotates it has 3 pointers on it that have settings to have the fan off, on and limit. Interior house heat can trigger the fan to come on all by itself by the pilot and along with higher temp in house that puts the temp in the furnace higher than the fan's 'on' setting.

I am familiar with the Honeywell combination limit/fan control. It is not the part I am speaking of. The part I am speaking of is some kind of blower timer located near the burner compartment in the lower right hand corner.

this is the part I ma talking about:

http://americanhvacparts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=FLT1005229&Category_Code=fl-tdl3

It says it has the following function:

This Blower Control Relay and Limit Control is Found on Intercity Products, Heil, Tempstar, Comfortmaker, Snyder General, Coleman Forced Air Furnaces.

This Control Delays the on and off times of the blower fan resulting in increased heating efficiency. Incorporates a safety limit input circuit required for safe operation of forced air furnaces.


I am not sure why this part is coming into play with the cooling cycle.

It says it has the following function:

This Blower Control Relay and Limit Control ...........


Are you still sure it is a TIMER based on the very wording you quote? This 'relay' may act as a contactor of sorts that converts low voltage 24v to 120 v and contacts may be stuck, where you need a new relay.

Thanks for your help ecman51. Sorry about the ambigous wording, but this is not a typical limit/fan control since there is a Honeywell fan/limit combination control there as well. I will try replacing this.

Thanks again