Carrier Pressure Switch Continuity Test

Old 11-10-21, 04:23 AM
Thread Starter
Join Date: Mar 2008
Posts: 67
Received 0 Upvotes on 0 Posts
Carrier Pressure Switch Continuity Test

I have a 1998 Carrier gas furnace.

I have an intermittent problem where the ignitor is not getting power when the furnace starts up.

​​​​​ I was thinking it could be the pressure switch or the board.

I used my multimeter to test the wire lead to the ignitor for voltage. There is no voltage. The ignitor itself shows 80 ohms of resistance.

I was testing to see if the pressure switch circuit was properly closing during the furnace start up sequence. Per a YouTube video created by an HVAC professional, I put a multimeter lead on each of the pressure switch terminals and set the multimeter to test for continuity. Per the video, when the pressure switch circuit closed the multimeter would alarm for continuity.

I turned on the furnace, and the continuity test blew the panel fuse.

During the furnace start up, the gas valve does open but of course, it closes again if the ignitor does not turn on. So perhaps the pressure switch is not the issue.

What could be causing the ignitor to not get any power ?


Last edited by jsbigger; 11-10-21 at 06:40 AM. Reason: clarify
Old 11-10-21, 10:17 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 62,017
Received 3,407 Upvotes on 3,057 Posts
You can't use continuity on a live circuit. You put your meter in AC volts. Connect the leads across the pressure switch. You should measure 24vAC. When the inducer is running you should measure 0v across the pressure switch. If the switch doesn't close.... the igniter won't heat.

Pull the pressure switch hose off. Check the hole where the hose connects to the inducer or burner chamber. There is typically a small hole all the way down INSIDE the fitting. That needs to be cleaned with a pin or small piece of wire or drill bit.


Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: