Hello daddy,
Is this the 4 prong mercury switch that plugs in to the valve or sits on the sidewall?
Billy
OK, this will sound very basic at first... but I like to start from scratch so I do not miss any thing.....turn the gas off at the gas line shut off. Take off the drip leg cap, and then open the valve briefly to see if you have good gas supply.
Ok,
follow the gas line back from your gas valve until it leaves the furnace cabinet. once it leaves the furnace there is a Tee. Off the bottom of this Tee is a short piece of pipe with just a round head cap screwed on the bottom. This is the cap I want to take off just to make sure you have gas supply at the furnace. Do you have an electric meter to check volts with?
Have fun at the dinner, I will leave some suggestions for you to follow and you can look them over when you get back
Hope your dinner was nice...
first see if you have 24 volts going to PV on the gas valve. The mercury switch does not come into play until the pilot is lit. you should have 24 v to pv the same time you have spark. If you have spark and 24 v to pv without gas coming out of pilot...then the gas valve is bad. If the gas valve is not getting 24 v to pv, go back on that wire to contol and check there. I have a feeling you may have a bad gas valve. but check voltage first.
HVAC Mechanic
State Licensed Mechanical Contractor, Heating, Cooling, Oil Burners, Heat Pumps, Boilers, Geothermal
Once the furnace is trying to light put one meter lead on PV on the gas valve and the other meter lead to the cabinet or ground.
On the valve itself...what terminals do you have?
Either one would be great
Your welcome, just let me know.