Furnace fires up but no fan/heat

Users who are viewing this thread

Jsmith2022

New Member
Messages
1
Reaction score
0
Points
1
Location
California
I have a gas furnace (forced hot air) that was working fine a week ago. This week I noticed it wasn't blowing any hot air, in fact no air at all when the heat is on. I can hear the furnace fire up and run when I switch the thermostat to "heat on" but no warm air comes out. I thought the fan was not working - if the thermostat fan switch is moved to "on" from "auto", still no warm air. To be sure I turned the furnace off via the HVAC switch and turned the fan on, to my surprise the fan was working. I changed the batteries on the programmable Honeywell thermostat, then finally replaced it with a new Honeywell programmable. Same symptoms, furnace on but no warm air. Fan turns on when heat is in off position. I am hoping this set of symptoms will identify a failing part in the furnace. The unit is a Carrier Crusader, gas from the 90's, heat only. I cannot find a model number markings. Any help would be appreciated!
 
Last edited:

Breplum

Licensed plumbing contractor
Messages
1,162
Reaction score
444
Points
83
Location
San Francisco Bay Area
You have established that the fan is good.
The heating sequence is that flame rod needs to detect flame on fire-up. That is a pick and hold function.
You need to watch the fire-up sequence.
Definitely pull the flame rod assy and use emery cloth to thoroughly clean it.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks