# RUUD ACHIEVER 90 PLUS -Pilot not igniting - URGENT**



## beenthere (Oct 11, 2008)

Blocked vent, or a bad pressure switch.


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## sjahan22 (May 24, 2008)

Thanks. How can I find out if it is a blocked vent or bad switch ? I pulled the rubber tubing out. That seems to be clean inside. Can I jump the leads on the pressure switch to find ?


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## sjahan22 (May 24, 2008)

Ok, I cleaned the Vent pressure hose by blowing into it. Changed filter. Turned power off, wait for 10 mins and turned it back on. I can hear see the blower fan starting and after few seconds, the hzzz sound of gas valve opening and then the click of ignitor, but nothing happens? It tried couple of times and then went into a one hour lock out. (one blink on the cpu board) do u think my problem is vent pressure switch or ignitor ? can I jump the vent pressure switch to test

thanks


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## beenthere (Oct 11, 2008)

The ignitor is suppose to energize before the gas valve opens. Sounds like you have an ignitor problem.


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## sjahan22 (May 24, 2008)

Thanks Beenthere. 
(1) am i supposed to get any reading (vac) off the vent pressure switch when the fan is running ? How can i make sure the pressure switch is working 

(2) is there a way to test the ignitor (with multimeter) to make sure it is faulty before replacing ?

Appreciate yr help


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## beenthere (Oct 11, 2008)

If the pressure switch wasn't closing, you would get no gas. But, you can put your meter across it while the inducer is running, it should read 0 volts if its closed.

You can pull the ignitor and look for a crack, or you can ohm it out, looking for a crack is easier.


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## heatycooly (Mar 11, 2011)

To check the ignitor set meter to ohms if you read a number typically 60-100 ohms if reads ol or ofl then it is bad the pressure switch while the vent motor is running should read 0 this means the switch is closed which is goodto check vent you can just disconnect them the intake first then the exhaust (1 minute at most) if it runs with then there is your problem if it doesn't run check your drain line if it is plugged the pressure switch won't close blow it out with compressd air if their is a box with drain tubes going to it (a trap) blow that out too


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## sjahan22 (May 24, 2008)

(1) The pressure switch tied to the fan shows 0 VAC when fan starts and then after about 5 seconds, it shows 24-25VAC. So I am assuming that it is working ok. 

(2) The second pressure switch is for the VENT and it shows 0 reading, always - whether fan is running or not running.

This part part I didn't get:
>>>> If the pressure switch wasn't closing, you would get no gas. But, you can put your meter across it while the inducer is running, it should read 0 volts if its closed. <<<<

If I put the meter across the leads on vent pressure switch and then close the door, The blower fan will starting and after few seconds, the hzzz sound of gas valve opening and then the click of ignitor. 

(A) What vac readings should i be seeing on the meter when above events happen ?

(B) Are they one ignitor or multiple ignitors to pull out and inspect ? If I am not seeing a crack visually, i can wire up another multimeter on the ignitor leads - what vac values should i be seeing here ?

Thanks as always!


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## heatycooly (Mar 11, 2011)

You have to ohm out the ignitor not check vac if ignitor reads on your ohm meter OFL or OL that means open limit . As for the pressure switches the one is for the vent the other for the drains on amana furnaces for example if the drain pressure switch Is not closing three ignitor will energize but no gas valve in your case the valve is energized but no ignitor. Is there a led light that flashes after the fist time it fails? I am talking before it goes into lockout


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## sjahan22 (May 24, 2008)

heatycooly,
What should the resistor Ohm out at (what range should I set my meter while reading 200 Ohm?)

Beenthere,
I goofed up on my readings on the pressure switches. 

Closed = Circuit completed - correct ?

Pressure switch tied to the fan - I should have been measuring with one lead on the ground and the other lead on the connector base of the switch. Instead I was reading across the two connector base on the switch. I will re-read and report back.

Vent pressure switch, when it is closed (circuit completed) shouldn't be reading some value if measuring VAC or zero if measuring resistance ?

Heatycooly,
I did not notice any led other than a single blinking led showing lockout. I will repeat the process and see if there are any other blinking pattern

-Shaw


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## beenthere (Oct 11, 2008)

You should read across the switch while the inducer is running. And then check from one terminal to ground to make sure it has voltage tom it.


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## heatycooly (Mar 11, 2011)

All you need on the ignitor is a number other then 0 or OL. you do want to check pressure switch across both wires on switchand should read on both pressure switches 0vac if you read 24vac on either one of the switches that is what is causing your problem be it venting or drain


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## sjahan22 (May 24, 2008)

Gentlemen here are the results.
The problem was traced to Integrated Furnace Control board. IFC has a driver (T1) that fires the Spark Ignition Electrode. That driver is the problem. I verified by taking the spark ignition electrode outside - it is not arcing. I took that same spark ignition electrode and plug it into a similar furnace IFC and could see it sparking.

The board is $125, but it seems if i could find the T1 driver part, it should only be a few dollars.

I measured the resistance of 14.29 mega ohms across the solder connections for T1.
What resistance should I measure ? Also, is it possible to buy just the T1

Thanks
-Shah


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## beenthere (Oct 11, 2008)

Buy the board. They don't make replacement parts for them.


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