Tempstar furnace

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Old 01-04-09, 09:28 AM
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Tempstar furnace

I have a Tempstar furnace installed in 93. It kicks on and ignites properly about 8 times out 10. On those other unfortunate occasions, the cycle begins normally but will not ignite. It continues to make a rapid clicking noise UNTIL I jiggle the MV/PV connection; at which time the clicking stops and "whoosh" the flame ignites and it continues its cycle to completion. $205.00 later, the local repair man insists that jiggling the wire has nothing to do with it. Well, obviously he didn't have a handle on it, the furnace is still malfunctioning and I'm still jump starting it the same way. Any ideas would be greatly appreciated. ML
 
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Old 01-04-09, 10:41 AM
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What did the repairman tell you was the problem?

The rapid clicking noise is a spark being generated to light the pilot burner, but that's apparently not happening.

More than likely that's because either 1) there is no pilot gas coming from the pilot burner to light or 2) the pilot burner is dirty and needs cleaning.

Can you hear gas hissing from the pilot burner while the spark is clicking? You need to be able to determine whether gas is coming out of the pilot burner --- yes or no.

The MV/PV connection at the Honeywell ignition control provides the ground connection for both the main burner and pilot burner. If that's not making a good connection neither will turn on. So you should also examine that connection with care to see why jiggling has an effect.

It might be a poor electrical spade connector that needs to be replaced. You might be sending a small physical shock to the control module or to the pilot burner that is causing an effect.

You need to jiggle with care and observe the effect you are causing. Do this repeatedly until you understand what is happening.
 
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Old 01-04-09, 06:05 PM
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Thank you so much for the response. The repair man told me he wasn't sure what was wrong, his best guess was to replace the igniter; but that didn't fix the problem. His game plan was to continue fixing/replacing the "most likely" causes.
I'm on a fixed income and I simply can't afford for him to keep best guessing this situation at $80 to $100 a pop particularly since he refuses to intertain the notion that the MV/PV connection could be involved. I've been Jump starting the furnace at least once a day for the last 6-8 weeks. If I get down to the furnace while the "rapid clicking" is still going on, I simply take hold of the MV/PV plastic connector and wiggle it side to side (like a loose tooth) and Whoosh! On goes the furnace. If I'm not quick enough or if I've been out for a while, the clicking eventually stops and the fan continues to run. I then shut the furnace off, restart it, the clicking begins again, I wiggle the connection, and away we go. I'm getting tired of babysitting the silly thing though and I hope I can get the cause pinpointed. ML
 
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Old 01-04-09, 09:05 PM
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Frankly it's absurd for a repairman to talk about guessing that the ignitor is bad. It can easily be tested for continuit with an ohmmeter and 95% of the time a crack can be observed visually if one is there.

You didn't do most of the tests I suggested in the previous post. I really can't help you unless you choose to do them.

Also, I suggested that the rapid clicking noise you hear is the spark attempting to light the pilot. You need to verify that that guess is a fact. If so, you should be able to see the spark while you hear the clicking.
 
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Old 01-05-09, 10:51 AM
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I'm sorry I didn't give you a better update on the things I was to check out. I was so thrilled that I got a response, I just started rambling. First, the hissing. I've listened repeatedly to the sounds it makes when it operates correctly, and when it does not. When everything goes well I hear a brief hiss, a very short sequence of the clicking, and almost instantly the burner ignites. I can see the pilot light go on just briefly before the main burner ignites. Now comparing that to what happens when it doesn't start. I only hear the rapid clicking, no hiss at all UNTIL I reposition the MV/PV spade in its connection site. Then I hear the same sequence as in the normal cycle. The brief hiss followed by a nearly instant igniting of the main burner. If the MV/PV connector is a ground, does it make sense that the pilot would not be putting out any gas if the connection was faulty and by repositioning that spade, the connection is made and the pilot then ignites? Also, I can't SEE a spark at any time. Either it's not happening, or I don't know where to look for it, or I can't get in position to see it (I'm disabled). More than likely I'm just not looking in the right place. As far as the effect of repositioning the spade connector goes, it reminds me of an electrical cord that gets bumped or tripped over, the plug is still in the wall, but the connection is broken, so you push it back tight in the socket and it's fine. ML
 
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Old 01-05-09, 11:46 AM
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The spark is happening or the pilot wouldn't light. I just wanted to confirm that the clicking you describe is that sparking, rather than something else.


Since the ignition module starts up pretty reliably when you move around the MV/PV ground connection on the module, it's pretty clear that the ignition module is defective and needs to be replaced.

Everything else seems to be working normally.
 
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Old 01-05-09, 03:32 PM
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Originally Posted by Thispoorhouse View Post
The repair man told me he wasn't sure what was wrong,
Quite the repairman.

His game plan was to continue fixing/replacing the "most likely" causes.
I'm on a fixed income and I simply can't afford for him to keep best guessing this situation at $80 to $100 a pop......
I guess repairmen can operate like doctors, who keep billing you for TRYING to fix you, even though the various scans, blood tests, pills and whatever else they do, running up a big tab, has not helped. Maybe the court system figures everyone (specialists who try to fix stuff) can't be an Einstein, and figures that is simply life. I don't know.

.....I simply take hold of the MV/PV plastic connector and wiggle it side to side (like a loose tooth) and Whoosh! On goes the furnace.
Sounds like loose pin-type connectors in the plastic jack. You can spread the pins to increase their diameter for better contact.
 
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Old 01-05-09, 03:50 PM
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Originally Posted by ecman51` View Post


Sounds like loose pin-type connectors in the plastic jack. You can spread the pins to increase their diameter for better contact.


Heh, heh! This seems to be a favorite fix on this board!


Probably right sometimes, too, and overlooked. But in this case it's a Honeywell S8600 style ignition module, and the connection is just a 1/4" spade connector --- not too likely is my guess.

It's sounding like a bad ignition module, although there are some other things that are worth checking out.


I remember once I had an expensive Honeywell ignition module for a commercial boiler that wouldn't work reliably. I sweated bullets over it for 2+ hours and was ready to give up. I happened to lean against it --- and it fired up. There was some defect in the mechanism that held the control module against the lower circuit board. Simple --- but hard to test for and hard to identify!
 
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Old 01-05-09, 05:00 PM
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S/P, how did you determine it had Honeywell module? Did I miss something? Kind of sounds like a smartvalve problem(9500 series) but I don't know if they were so equipped.
 
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Old 01-06-09, 12:19 PM
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Thanks to all for helping me out. I'm slowly learning a little about furnaces. I've been looking at parts catalogs on line and trying to get a handle on what parts I'm looking at in the furnace. The MV/PV spade connector I'm wiggling back and forth is not on the module (the long piece that has the red spark wire coming out of one end) but at the (gas valve?). I'm not sure if thats the correct part name or not. There is little rectangular box with three connector points; MV, MV/PV, and PV that I think is sitting on the gas valve. The on/off knob for the gas is right beside it. I'm sorry I didn't know enough about what I was looking at to make that destiction before now. ML
 
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Old 01-06-09, 02:27 PM
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I'd start by clipping off the old connector and crimping on a new one. Are you feeling lucky today punk.....

Well, are you? [doing my best Inspector Callahan imitation]

I don't suppose joggling the other end at the ignition module produces the same effect?



If the new connector doesn't solve the problem, it sounds like a bad connection internally at the gas valve. That's surprising, because that Honeywell gas valve tends to be VERY reliable in my experience. But if it's bad, it's bad.

Replacing the gas valve should be done by a qualified repairman, who needs to set the gas pressure to match the input for your furnace.

Your best bet might be to shop around for the best price you can get since you'd know what needs to be done and the part you need.

Probably about a half hour job replacing the gas valve as an estimate, I'd say.
 
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Old 01-06-09, 03:55 PM
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Originally Posted by SeattlePioneer View Post
.

Replacing the gas valve should be done by a qualified repairman, who needs to set the gas pressure to match the input for your furnace.
Is it possible for a DIY'er to first install one themselves, and then do a couple checks like see what happens to the furnace heat rise?, and also time the gas meter's 1/4 or 1/2 foot dial based on the input rating? In case the person lucks out and the gas valve is preset fairly close?
 
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