ICP Furnace intermittent fault, now no longer lights


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Old 02-16-14, 09:07 AM
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ICP Furnace intermittent fault, now no longer lights

Unit info: Outdoor ICP natural gas furnace with Honeywell SV9501, case is 15 years old but has had it's internals replaced recently. I do not see any lights on the control board to even send out a blink code.

For about a month I have been trying to figure out why at seemingly random intervals my furnace would shut the main burners, leave the pilot going and the house blower going until I cycled the thermostat on and off. Sometimes it would shut the burners off within seconds of firing the main burners, others it would happen an hour or more later. It seemed to have the most trouble when ambient temperatures were in the 30-40s F. When it got down to 4f for a week it had no issues at all.

Yesterday I woke up and found that it had faulted over night (low of 30f ambient), I cycled it at the thermostat like I have been doing, but this time it didn't light. I then tried shutting it off at the breaker panel and rechecked; still nothing. After pulling the panels off to watch I can see that it is not even lighting the pilot light.

The draft inducer motor starts up, but nothing past that.

This is my first house and first time having gas heat, shortly after I bought the home I had a highly recommended HVAC tech come out and check all of the furnaces at the house. He confirmed that the unit in question has had it's internals replaced within the last year. The rest of the this system is original to the house (15 years). At the time he saw nothing questionable and the unit functioned properly.

I believe the intermittent issue and the current no-light condition is due to the SmartValve failing, but before I re-flow the solder or replace it. What are the basics I should check to rule out other possible causes?

I have a DMM and can check anything requested. I've also attached a picture of the unit with both panels off, please let me know if there are any other pictures/vids that would be useful.

https://www.dropbox.com/s/0n8rxmznga...205142017b.jpg

I plan on having the tech come back out this week, but wanted to take a crack at it myself since I have been investigating the intermittent start myself for a month now.

Thank you!
 
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Old 02-17-14, 06:29 AM
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I am not a professional technician.

Post the model and serial number from the name plate. A video of the furnace starting and shutting down might help.

Find the manual for your furnace and see what the trouble shooting and routine maintenance sections say.

Does the furnace give error warnings, such as blinking lights or a display with a number?

Is the electricity and gas flowing to your furnace?

Is the filter clean and the path of air from outside your home into the flames and out the chimney clear? Is the path of air through your heating ducts to and from the furnace clear? When the fan is on Is the blower actually blowing air? Are the blower wheels clean (just a little filth on them can stop them from blowing air even though they are spinning)?
 
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Old 02-17-14, 06:51 AM
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Thank you for the reply geo8rge.

Unfortunately the name plate and all identifying marks have been removed. I only know it's an ICP brand from what my HVAC tech was able to tell me.

I will get a video tonight , but there really isn't anything to video, the inducer fan starts, and that's it. Nothing ever happens, as stated there are no blink codes, in fact there are no LEDs to even light up.

Yesterday I used the wiring diagram affixed to the inside panel. To trace that the pressure switch was not closing once the fan came on, stopping the ignition sequence. I'm hoping it is the culprit for the intermittent start issue as well.

Where does one buy a replacement pressure switch? I have the part# and manufacture of the switch, but not finding much about the particular unit online. It's a single hose, two wire normally open switch.

I was able to find the pressure switch USED online, here TRIDELTA | CONTROLS PRESSURE | PRESSURE SWITCH SPDT 1 PORT 2 TERMINALS | Surplus City Liquidators

Tridelta FP6619 / HQ1065208TR but unable to find out the specs on wc and where to buy a new one, or an updated version.

If anyone can shed some light on it's specs/replacement #, etc. I would greatly appreciate it!
 

Last edited by mzman; 02-17-14 at 07:33 AM.
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Old 02-17-14, 11:02 AM
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I went out over lunch to see if I can find some model #'s for the unit itself. The only thing I can find on a piece of paper on the back of the control panel is PGAA30D1K, the rest of what looks like was a data sheet was ripped off...
 
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Old 02-17-14, 12:16 PM
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ICP( International Comfort Products) is a well made unit. I wouldn't buy a used pressure switch. Check out www. hvacpartoutlet.com. Before you do that make sure the tube doesn't have any cracks in it and there is no blockage.
 
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Old 02-17-14, 06:11 PM
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Isn't there a local HVAC parts place around you? If it were me I would remove the part and take it to the HVAC parts store and let them suggest a replacement.

On my furnace you can remove the leads to a sensor and connect them together. That causes the furnace to act as if the sensor does not detect a problem. It might be the same with your sensor, or it might screw things up worse, but it is your call. You can also use a voltmeter to test for continuity.
 
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Old 02-28-14, 08:26 AM
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Thank you for the help guys. As a follow up for future readers; I ended up ordering a replacement pressure valve, which got me back to having intermittent flame main burner ignition. I then took apart the SV9501 and re-flowed the solder connections to the wiring harness. That took care of the intermittent ignition.
 
 

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