Lennox Pulse gas furnace circa 1990. I am the homeowner. this past weekend, heater would not run. I determined it was the thermostat, replaced it, and heater worked perfectly until today. This morning, the thermostat triggered the heater to come on, the heater ignited but the blower did not engage. hetare then shut itself down. This cycle repeated until I turned off the heater. I am guessing that the blower or relay went south. Are there any diagnostic procedures I can follow to check out the problem? Unfortunately, my heater expert is no longer in the area, and before I call someone new I would like to have a good idea of what is really wrong with the unit. Any help appreciated.

Thanks.
Bill

 

The wife read me the riot act about getting this fixed today, a cold front is coming in. My suggestions to bundle up fell of deaf ears , so to keep the peace I called a service co. $569.00 later, the blower motor is replaced and the unit is working normally. Tech says motor was seized. Oh well ....

 

$569 for a blower motor!?!

did they do anything else?

 

$95 for service call
$466 for blower motor
$85 for operational assessment
$15 for flapper valve

Total $661 + tax 6% = $700.66 for a $200 blower motor. Sweet.


If it weren't 30 degrees around here, I would have done it myself.

 

I am not sure what's the $85 for operational assessment is?? Did they say?

I must admit, that motor is still pretty high! Is this a regular motor or variable speed?

 

I think it is a variable speed motor. The operational assessment was a my asking the tech to make sure that every thing was operating normally before he left. He spent about 1hr 15 min on the job to do all the work.

man, I'm in the wrong business

 

Ok, Yeah the variable speed motor are expensive.

Was this a Lennox Dealer on this?? Did he check the heat exchanger (doing pressure testing, cheacking or replace the flappers?)

 

I'm having the same problem...burners kick on but no blower. My blower will run when I change the switch on the thermostat from "auto" to "on". Naturally I need it to run in "auto" Any ideas what that might be?

 

What model do you have?

It could be the heating speed of the blower motor or control board..

We need more info.

 

Thanks for inquiring. Here's what I know. Furnace is Lennox Pulse 21. Model is G21Q4-80-1. S/N is 5892G09188. Probably about 12-15 years old. Existing furnace in house when I purchased a year ago. I replaced the dial thermostat last fall when I moved in with a Honeywell programmable before the first heating season. Everything heated fine then, blower and all, but not this year. Replaced batteries in thermostat as a precaution but this did not resolve anything.

During summer it cooled without issue, blower and all. Now in heat setting, it kicks on and runs (you can hear the hum pretty easily) for a few minutes until it kicks off without ever running the blower. When powered up and calling for heat, I can see (what I think is) the fan relay rotating inside the unit as the temp increases in the unit. It then shuts off and the relay rotates back down. It then starts all over again.

If I switch the fan to "on" when calling for heat everything runs fine and I warm up the house. When thermostat reaches temp and shuts off I just have to walk back and switch the fan to "auto" to shut it back off as well. I'm limping along in this mode for now. When I dont want to heat I'll turn the thermostat to "off" as a precaution until I get it fixed.

 

You can leave the heat on, and leave the fan in ON.. no harm is done.. You are safe to do this..

Have you called for service??

if not, we can try walk you on this.

 

Have not called for service yet. I'm game to try a few things first if you have some suggestions. If it gets too complicated I'll have the pros come out and take a look.

 

If you are handy and able to read the wire drawing to trace the heating speed wire for the blower motor.. take some reading.. If you are getting power to the motor in heating, then you will need a new motor..

Do you see any sticker on the furnace if it has been insepcted by a lennox dealer?

If nothing. I would call a Lennox dealer and have them service it.. Ask them if they have a pressure test kit to check the heat exchanger.. If they don't, ask them who would.. You wil need to get it tested. Lennox had a lot of problems with these heat exchanger.