Flame sensor micro amps

[wishful]

Lennox G2003E-75-2. Has spark-to-pilot module and seprate sensor rod. It has a pretty blue pilot with good impingement, I cleaned the sensor rod with a soft brass brush and clean white paper, my Fluke reads 1.4 micro amps in series with the sensor. The main valve wont kick in and the furnace goes into lockout. What micro amp reading should I be getting? (I think I have a weak module.) Thanks guys, from a 'retired' tech with a bad memory.

[tinknocker service tech]

your reading seems ok

[docholiday]

so what is the voltage from the sensor to ground?

[ej45]

Check for voltage at the main gas valve terminals or at the module output serving the gas valve. If your microamps are good your module should energize the gas valve main valve.

[Steve Wiggins]

Try reversing the polarity. Your 1.4µA reading should go up to 2.8µA

[wishful]

I'm going back tomorrow, this furnace has worked fine 'till this season. Did you mean to check the polarity of the 120vac that powers the furnace? I will do that before replacing anything, however I do need to check for 24vac at the gas valve and continuity of the main coil on that valve also. The spark that lights the pilot keeps clicking untill lockout. I do expect voltage from the sensor to ground, but then again I don't remember what that reading should be. I do remember on some HSI units that if you get 103 to 105v from the sensor to ground, then the module is bad. Is it the same for spark to pilot? Thanks again guys.

[Jultzya]

Originally posted by wishful
The spark that lights the pilot keeps clicking untill lockout.

Here's your sign!




I'm kidding BTW.

[klyons20]

make sure all you limits are good..

roll out switch, high limit, provent switch, etc, all these could hold it back. What model of controler would help.

When u get a pilot jump pv to mv. This will verify you have a good gas valve.

regadrs,
kelvin

[tinknocker service tech]

ake sure the connection for the flame senser to the control is good and tight. i have seen a lot with loose spade connections and the true signal never reaches the control. i have also seen cases where the clip that holds the senser in place is loose and the senser drops down a little and dose not get the right recifacation.
personaly i think you have a defective control. but just a guess

[MadeinUSA]

Why don’t you idiots just give your phone numbers out so you can give every homeowner in the country step by step free advice so no contractor in the country can make a living.

All you idiots are doing is building a file where every homeowner can go hit search and solve their problems here instead of calling a local contractor.

What the heck do you think the Pro technical forum is for? Did you ever possibly think it might be to discuss matters such as this?

[borgis]

Hey made in the usa good point, i hope they listen to you.

[Steve Wiggins]

Yeah I agree. By the lingo he was using he sounded competent but after reviewing his past posts I now realize he is an illegal side jobber being very selfish in taking work away from legitimate contractors. Sorry wishful, no more technical help.

[tyreman]

One must keep an open mind.
it could be an "impossible" to clean impregnated sensor rod even another malady of same.
OR could be 'nother issue entirely.

[t527ed]

early model g20 has the blues prolem

[Milk man]

Originally posted by madeinusa
Why don’t you idiots just give your phone numbers out so you can give every homeowner in the country step by step free advice so no contractor in the country can make a living.

All you idiots are doing is building a file where every homeowner can go hit search and solve their problems here instead of calling a local contractor.

What the heck do you think the Pro technical forum is for? Did you ever possibly think it might be to discuss matters such as this?

Since everyone can get into the pro section what is the difference?

This type of thread is what catches my attention. This is the tread that we can teach each other. Some tech will read this thread and remember that older G20s had an issue with the original control module. Now a few HO's will also. Bitter medicine.


As far if Wishful needs to be helped, not my call. I spend too much time here as it is, and don't need to be policing this site.

[tinknocker service tech]

check the heatexchanger while you are there. the G-20 had problems with deteorating hx. seemed to me it was the hx that was painted that had most of the trouble. lenox later changed it to a nonpainted one and seemed to solve the problem.

[wishful]

Hey folks, I didn't mean to tic anybody off. I have deals with contracttors in this area to help out when they are overburdened or shorthanded. Since I got cancer I can no longer work full time. But a lot of days I feel good enough to be useful, and with some of the young guys needing more experience we can all work together. On that note, I found my tech manual for the Lennox in question, and the furnace will either be fixed right or condemned. By the way-- do you think the average HO would know what flame rectification is, or microamps for that matter.
I was just using this forum to jog my memory. If you do your jobs well & charge a fair price, then you have nothing to worry about.
Thanks again to the good folks with the helpful attitudes.

[lakeman1234]

Steve Wiggins
Professional Member

Registered: Nov 2000
Posts: 4667
Try reversing the polarity. Your 1.4µA reading should go up to 2.8µA
__________________


Steve how do you figure that? If you reverse the polarity on a DC ampmeter you should get -1.4uA. Or are you just trying to be cute? The only time I have seen what you said was when my multimeter went flakey.

Sounds to me like the pilot orifice is pluged up. Try replacing it. We seem to have a lot of problems with them on propane especially in damp basements and Roof Top Units. By the way you should have around 3 to 5 uA of flame current.

[Edited by lakeman1234 on 10-24-2005 at 12:42 AM]

[drfluke]

Don't worry too much madeinusa.
Most homeowners don,t have the proper tools to do the trouble-shooting, much less what to even look for.Just take a look the money you've invested in your equipment to do what you do.Years ago I owned a tire & auto repair business.Busted my --- 15years trying to keep up with Sears,PepBoys,Sams,...etc.When I soldout I had over 50K in equipment and trucks air-compressors,balancers...you name it.Now when I have a flat or a tire out of balance I have to go to someone who's in the tire buisness.Even though I know how to do it..I don't have the equipment to do it.I remember when I worked for a restaurant chain just about every gas fired appliance they had used RobertShaw valves. At the time i could tell you anything you needed to know,but now I'm trying to keep up with the rapidly changing HVAC technology I can't remember that old stuff anymore.I didn't use it,so I loosed it.What's killing me is all these shoddy cut-throat competitors.It's hard to turn a buck anywhere. I can't have the whole pie but I can sure have my piece.Just find your niche and keep a bead on it.Don't be afraid to tell someone what you know, thats how we learned what we know...All of us had to learn at one time too. I visit this site to laugh and LEARN...it's FUN! I've had some Vets on this site save my butt a lot of times just because they wanted to and I really appreciate them.By the time you know alot it's time to die.Don't let all that experience and knowledge go quitely into the night, tell me what you know and your eyes have seen , WE NEED YOU!

[2hot2coolme]

I don't know what kind of advice you guys are giving this poor guy, but you're gonna get him hurt, it's obvious the problem lies in the time delay in the ODFM this is the first thing you want to check before goin through all that other trouble.

Good luck