Nordyne M1MB 070A BW no ignition

[Dana57]

Hello having trouble with the furnace (3years old cleaned it last winter it seems to run dirty)when calling for heat Thermostat turns on the draft fan, but the electric ignition does not seem to light the pilot or burner( no clicking sound thought it used to click). The furnace worked the day before.

I can smell gas (Propane). Getting the red LED light blinking twice =(pressure switch open). No yellow LED.. AC works blower moter etc. pulled the gas valve essembly out and cleaned every thing disconnected the lead wires to the ignition and while calling for heat with draft blower on could not get any current going to the igniter(with igniter disconnected). I have read many of the FAQS here and it sounds like there is a pressure switch that senses the draft fan and in turn charges the igniter and or opens the gas valve? Put everything back together but same results.
I had trouble last winter getting the main burner to ignite but once I cleaned all the soot out it worked fine.

[Robert]

Hi,

Be sure induced draft motor is running strong, air pipe to motor is clear, tubes from motor to pressure switch (round disc with tubes and 2 wires) are clear, connected tight and not kinked and be sure one of the 2 wires has 24vac to ground.


IF all seems ok, then probably a bad pressure switch.


Pressure Switch # 632453 can be seen and ordered from here by paging down:

http://www.aberdeenhomerepair.com/store ... ure-switch



Thanks,
Robert

[Dana57]

Thanks Robert.
If the vacuum switch has failed would the result be the igniter circuit not closing and giving the igniter current? Would the gas valve still open because I thought I could smell gas?
I could not find any current going to the leeds of the igniter. Although I only tested the leed wires themselves and not against a ground.
Also you mentioned the induced motor being strong. The induced motor sounded a little rattly while it was running I don't remember it sounding this way previously. The motor may be week and not pulling enough vacuum. Or the tenant may have left the thermostat continue to demand heat for an extended time resulting in an over taxed motor. This would not of course be the origination of the igniter problem but could be an additional side effect.
This home is 2 hours away (and remote) so it is hard to check parts until I make another trip so I want to be as prepared as possible when I go up there.

[Robert]

The pressure switch contacts must open at end of cycle and must close at start of cyle or nothing else will work. No gas, ignitor ,etc.. .


Remove motor and clean wheel and motor area and look for debris clogging things up.



Thanks,
Robert