My Goodman GUPS120-5 Gas Furnace only runs for a short time before shutting down the flame EXCEPT if I leave the filter out. I have tried a new clean filter and still have the same problem. Initially I replaced the thermostat and still had the same issue.

This issue started happening right after I pulled out the blower motor and cleaned and replaced it. After reading around I see possible causes could be a limit switch, a pressure switch, or a flame sensor??

Possibly cleaning the blower asy I did something to lower the suction that the fan produces so it is not drawing enough air but I don't see how this should be the case.

Please help. Right now I am running the furnace with no filter and it is working OK but as soon as I add the filter it shuts down the main flame after a minute or so.

Thanks in advance.

Did you put the blower wheel back on after cleaning so it turns in the correct rotation? If it is running backwards that can cause a problem with enough air flow to kick the furnace off on high limit.

I never took the blower wheel out of the housing so I know the blower wheel is on correctly and spinning the right direction.

If all registers and return airs are open and no furnace adjustments were made and the blower is blowing the same volume of air as before then you shoule not be having a problem. I suggest you revisit the work you have just done since that is more than likely where the problem lies.

Make sure the blower is exactly as it was before removal especially the blower housing where the wheel fits in. There is a sheetmetal door that is usually held on with 2 screws that helps close up the opening where the blower wheel fits down into the housing. I have seen that part if it is missing cause many blower problems.

I took the blower out and reinstalled it and no change it runs OK with no filter but shuts down the flame with a filter in place. The blower housing has L brackets that slide into a dovetail slot on the furnace so there is no real way to mis-position it.

I used to be able to run the furnace with as many vents closed off as I wanted to direct air to different parts of the house (lots of back pressure). Right now with all vents open or some closed I still get the same problem with the furnace shutting off with the filter installed.

The logic board for the unit is attached to the blower housing. Maybe I changed some connection to the logic board when I cleaned the motor.

Any other ideas? Could this be a flame sensor or an air pressure sensor or something like that? I don't find a flame sensor in the manual for this furnace. It looks like the limit switch is also the flame sensor?

You may have other airflow restrictions (dirty a/c coil or secondary heat exchanger) and the air filter is enough resistance to "cross the threshhold" and trip the high limit. A temperature rise test might reveal such issues.

There could be many reasons for your furnace failure after you worked on it. Since by now you have revisited all the work you did and still have not found the problem it migh be wise to call for On site service to get your unit running properly. It is possible some wiring changed as you removed the blower or as you say changed some connections to the logic board when you were cleaning. Since I have no idea what you did I can be of little further assistance except to say that the situation you have just because of a air filter is very strange indeed and in all my years in this business I have never heard of it before.

If you locate the flame sensor clean it with sand paper. Looks like the sensor might be with the pilot on this model. See diagram below.

Hi. You have a restriction some where. It sounds like your furnace is sitting on a hole under it and that hole is not cut out big enough. Now when the filter is in place that also slows down the air and is just enough to kick it out on hi limit because the cfm is to slow and is not keeping heat exchanger cool enough. Then once it cools it will run again for a few then same sht. Also the inside of your AC coil could be clogged. Call some one because it is a shty job and worth the $125-$150 to have them take it apart and do it right. You may call me at (949)228-1370 I am 3rd generation HVAC company owner. Not a lot I have not seen in this field. Dennis.

LoL I Have the same problem , My furnace will only stay working if the filters are removed. We have replaced the thermocouple, gas valve and flu cap on an intertherm heatrite mgh-065-abwn-06. We have looked at the acoil and it looked clean on both sides on the top. There is a fresh air intake up next to the flu that we can feel some cool air, so I figure that's not plugged.

If I light the pilot with the filters installed I can get the furnace to start and heat for about three to five minutes before the flame shuts of and the pilot is out the blower will run for another minute or so then that's it have to light the pilot again.
Any help to solve my problem would be great ,I really don't want to run without filters thanks