HVAC help needed.

[Shadowrider]

I have a Goodman unit and it's acting weird too. It would light and then go off. So the manual says that the blinking light code is low/no gas supply. I check the hot water tank and it lights normally. So I go up to Johnstone supply and get a new flame sensor for about $4.98. Plug it in and it's fixed. That was a couple of weeks ago and I've just caught it doing the same thing only not near as bad. It will run a good while and then cut off prematurely, go through it's routine, and then relight and go until thermostat cuts it off normally. Mine will do 3 attempts before failing out for an hour and retrying. So far the retries are working. Think I need a new gas valve.

 

[tyromeo55]

It really seems to me like a thermostat error. Once it cycles normally, the thermostat (when the heater is off) doesn't click or anything when the temp goes below the set temp - but it only does this if the light on the circuit board is blinking 4 times - which means that the system is in "soft lock out"?.. so it would be preventing the thermostat from even clicking (which is, I assume closing R to W)? That's the thing that stumps me - the occasional blinking (red 4 times) light on the circuit board shouldn't happen if it was a thermostat problem, but would it prevent the Thermostat from actuating?

Just a guess ....
Guess A... upon calling for heat he thermostat is swinging back and forth ( open close open close ) in rapid succession. The board senses it as a fault and does a soft lockout ( wont call for heat until a No call is sensed)
Guess B... there is a problem in the Stat's circuit board or in the Stat relay where it has a higher impedance then spec'd for the board
Guess C... The stat wire is messed up somehow ( mice maybe?) and is not making a proper connection ( also high impedance)


Before you just go out and buy a new Stat, , spend a little time shorting R and W at the thermostat and see if it will act normally. Mark and remove wires at both ends. OHM the wires one at a time between each other making sure you dont touch them with your fingers and get a false reading. Then short all the wires at one end and ohm them again if a wire is bad its reading will be quite a bit off from the others

 

[Rooster1971]

Frigidaire used a couple different ignition set ups. One is a smart valve set up and has several wires including the ignitor that plugs into the valve. The ignition module is built in valve. It also has an indicator light on valve. I doubt this is your set up due to you saying the light is in the control board. This set up sucks.

Sounds like you have a more conventional set up. If it's lighting and going right back out, clean flame sensor and check where sensor plugs into board. Sometimes this is in about a 10 pin plug on board. Make sure that wire is pushed in good on that connector. Reverse polarity or open ground at receptacle will also cause the furnace to light and go back out. I doubt this is the case since it is working intermittently.

If it's not even trying to light and you are getting the failure to light code, you need to check to see if you are getting 24 volts at gas valve after ignitor glows. If no voltage check wires to plug assembly. If connections look good, some even have plugs through blower deck, the board is bad. If you are getting voltage to valve after ignitor glow and valve isn't opening it's probably bad valve.

Hope that helps. Pm me your number if you need help over phone, I might can help. I own an hvac business in okc.

 

[eaglerjs]

I have a Goodman unit and it's acting weird too. It would light and then go off. So the manual says that the blinking light code is low/no gas supply. I check the hot water tank and it lights normally. So I go up to Johnstone supply and get a new flame sensor for about $4.98. Plug it in and it's fixed. That was a couple of weeks ago and I've just caught it doing the same thing only not near as bad. It will run a good while and then cut off prematurely, go through it's routine, and then relight and go until thermostat cuts it off normally. Mine will do 3 attempts before failing out for an hour and retrying. So far the retries are working. Think I need a new gas valve.

make sure you have good tight conections at the flame sense rod and where it goes into the control ckt. Also on goodmans, the pressure switch can give simular symptoms.

 

[HMFIC]

EZ did you freeze to death or get this fixed?

 

[ez bake]

EZ did you freeze to death or get this fixed?

thanks man - so far it cycles normally for 2-3 cycles and then goes into soft lock-out (4 blinking red lights) but within 30 mins or so, it kicks back in and cycles normally for 2-3 more times... rinse, repeat.

got a new thermostat (I know... I should have checked wires but it wasn't that much and I've been wanting to upgrade it to a programmable one anyways) - same thing.

wish I had time to mess with it. between work and having to drive all over for kids' stuff, I've got no time at all (in lone star now at a b-ball game).

 

[twoguns?]

I now its just a ..simple idea...but check/redo all of your connections. Low and high voltage...they sometimes corrode after time...and its basically free.
Oh just saw your amount of time limits...when you can if your still having problems.

 

[ez bake]

I now its just a ..simple idea...but check/redo all of your connections. Low and high voltage...they sometimes corrode after time...and its basically free.
Oh just saw your amount of time limits...when you can if your still having problems.

Did that first man. Re-seated every connection, made sure every ground screw was tight (checked for corrosion).

 

[ez bake]

Awesome new update.

I just got home and realized that the fan is blowing and there is no heat (don't know how long that has been going, but with the fan set to auto on the thermostat, the fan now stays on.). One (slowly repeated) flashing red light, which means: "Limit Circuit Open" I guess. I can't seem to get the fan to go off unless I flip the to the unit off (thermostat on all positions: heat/off/auto fan - on/auto).

Breaking out the space heaters (and firing up the gas fireplace) and throwing in the towel. I'll call someone on Monday, I just don't have the time to mess with it right now.

 

[twoguns?]

Yeah sometimes its just something simple ....then sometimes ya gotta call in the guys with all tha tools.
Good Luck