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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8768
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My gas valve is clicking on my carrier gas furnace, propane

Customer Question

My gas valve is clicking on my carrier gas furnace, propane conversion.
Submitted: 7 years ago.
Category: HVAC
Expert:  Phil replied 7 years ago.

Phil :

Hi,This is risky business in the blind, not responsible for damages on your end. Click 'accept' when satisfied.. or we can get another expert.

Phil :

There were stink bugs in the gas line between the burners and the gas valve? good work on finding them.. if it still doesnt work, there are probably bugs inside the gas valve itself keeping it from opening. taking those apart can be a problem. but you can remove the entire valve and try blowing it out with compressed air with little liability, but dont use much pressure. when you put the valve back in make sure it works well. and that you didnt damage any parts inside, the diaphragm for instance... make sure the burner flame is all blue, and the gas valve opens and closes well... keep an eye on it... you might also have the furnace inspected by a local pro..that wont cost much if all he has to do is look it over.

Phil :

Look this over and get back to me, we can go from there, Phil

Customer :

There is virturally no way the stink bugs can enter the gas valve. It appears that it is a switch problem. The gas valve has a saftey shut off that opens and closes when another part of the system is having a problem. It is a carrier 58GFA100.

Phil :

Carrier uses Robt Shaw and Honeywell gas valves primarily.. you are very right that the bugs cant enter from the gas supply end, but we got a call here last week where they had crawled into the outlet orifices and up the gas line around two bends and into the valve as far as they could go... but as you say, not past the valve diaphagm seat,

Phil :

but thats rare,

Phil :

Where were the stink bugs specifically?

Phil :

Is the pilot light working?

Phil :

The large stink bugs have baby stink bugs, and those are very small, and they can crawl into very tight spaces.

Phil :

are you saying that a relay on top of the gas valve is clicking, or the gas valve itself.. thats an important detail..does it sound like light weight metal contacts clicking? or a slightly heavier more muffled sound like a valve seat opening and closing.

Phil :


Customer :

I can feel the gas valve clicking. It is coming from the back. The pilot light is lit, indcer motor starts and then stops in response to the clicking of the gas valve. The blower works.

Phil and other HVAC Specialists are ready to help you
Expert:  Phil replied 7 years ago.

Thanks..thats good information.


The way that furnace works .. is that on a call for heat from the thermostat the inducer motor is engergized.. it has an end switch on it (or a pressure switch is used) to insure that the inducer motor is running.


If its running, then the gas valve gets voltage and opens.


the fact that the gas valve and inducer motor are going on and off tells me that its either a bad inducer motor in a very unusual failure mode, or that its getting an irratic call for heat signal... there are many potential causes.


we will look into them one at time.


Do this, find where the thermost wires land in the furnace.. a red, white, yellow and green. all in a bundle, jumper red to white, and tell me if the clicking stops and the furnace fires up or not.


If it still clicks with red and white temporarily jumpered,,,then odds are its a bad control card. in that case try unplugging and replugging all connections to at a time, with an eye toward finding a loose connection.


Let me know, we can go from there, Phil



Customer: replied 7 years ago.
I jumped the red and white and no fire. The inducer fan just spun slowly.
Expert:  Phil replied 7 years ago.

Thanks that was a good check and a superb observation regarding te inducer fan,,, if it spun at less than 1750 rpm or so, as in 'slowly' the fan motor is bad, or for some very unusual reason not getting the full 110 volts it needs,


if the fan isnt working right, its Hall effect switch will not close allowing the gas valve to open,, if it doesnt have a hall effect switch, then the furnace has a pressure switch that will hold the gas valve off....


Having said that,,, it still doesnt explain the clicking,


so we several things going on at once here,, that dont add up,


Do this as a test, find the 24v transformer, run wire from both of its terminals to each of the two terminals on the gas valve,,, as a test only,,, for no more than 4 seconds, the gas valve should open with no clicking


If the gas valve clicks then it is a gas valve problem If the gas valve opens cleanly then its the hall effect switch on the inducer fan or the combustion chamber pressure switch causing the gas valve to repeatedly click.


do that check, get back to me




Customer: replied 6 years ago.

Is there a way to by pass the combustion chamber pressure switch or the hall effect swithch. What does the 24v transformer look like.


I'll accept the answer now but still need information. The last time I accepted before I had the problem fixed it costs me $400 because I didn't get any response after I accepted the answer.

Expert:  Phil replied 6 years ago.

Hello. as long as you keep posting this thread I will keep answering.. and that should keep the thread alive.. Im in everday for 14 hours on and off. If i dont get back to you notify the JA management at [email protected] that you need to make contact.


If the conbustion chamber pressure switch has only two wires on it. (most do) you can jumper those across as a test. some OPEN though when pressure is present so take one wire off to check that.


The hall effect switch is a bit harder to spot because its harder to tell the power wries from the burner fan from the hall effect switch wires.. but if you can separate those you can jump the hall effect switch as well.




The transformer is heavy, about 1 lb, iron core visible, side of a mans fist. 110wire in the back.. two screw terminals out the front for 24 volts.



Stay in touch, thanks for the accept. Phil