Miller Mobile Home Furnace Model Cmf80-ag


Old 01-03-08, 09:55 PM
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Angry Miller Mobile Home Furnace Model Cmf80-ag

I have been having issues with my furnace for a week. First it wasn't turning on unless i manually did it, once it kicked on the blower would not kick in. I called a service repair man yesterday and he replaced the pump coupler and nozzle and it worked great. It was working good this morning and in fact it was too warm in here so I turned the thermostat down from 75 to 65 and it was nice and comfortable.

Late in the afternoon it was getting a little chill and by 5 pm it was cold in here. So I went and turned the thermostat to 70. After an hr it felt colder and I realized the furnace had not started since i turned it up.

I manual started it, it kicked on, ran for a min before the blower kicked in, blower ran for a min, blew hot air out and then stopped. About 2 mins later blower came on again for another 60 secs blew hot air out and then stopped again.

Another hour went by, didn't turn on still cold in here so I manually started it again, same thing as above. And I have been doing this this every hr trying to keep it warm in here which it isnt working...ugh

I checked filter it is clean. I vacuumed the vents, and I even tried to see what cycle the thermostat was set to but the thermostat is like no other I have seen before, its a miller to and I think its the original. The trailer is an 1989.

I am broke, paid my last $218 yesterday to fix the pump nozzle and I am cold, I have no clue what to do.

The door to the furnace is warm after it runs for those few secs and I don't think a fan is turning on when its running but not sure...

Any suggestions???
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Old 01-03-08, 11:41 PM
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You seem to describe a warm air forced air furnace, but you talk about a pump coupler, which is typically used on a Bell and Gosset circulating pump with a boiler. Are you sure it was a pump coupler that was replaced?

Also, you talk about a pump nozzle, and I don't know what that is.

Is this an oil fired furnace or gas? Natural gas or propane?

The symptoms you describe suggest you have a forced air furnace with a fan that wont start and operate. When that happens, the furnace can't get rid of all the heat produced, and the furnace overheats, causing a temerature sensitive limit switch to shut off the burner and prevent a fire.

So you should check the fan to see if it has power to the fan motor. You may notice that the motor is quiet, but then hums as it tries to start for thirty seconds or so before shutting off again without starting. Fan motors typically have their own temperature sensitive switch that turns off the power if the motor overheats, again to prevent a fire.

Does the fan have a motor separate from the fan and driven by a motor? You can try putting your hand on the motor to see if it's obviously hot ---but don't burn yourself. Also, try turning the motor pully to see if it turns freely. If it's binding up and hard to turn, it probably needs oiling --- usually there are two oil ports and it uses a light machine oil like 3 in one oil. If you are lucky you can oil it and push the belt and get it started. If it wont start or stay running it may be damaged and need to be replaced.

If the motor is inside the fan, you have to do pretty much the same thing to diagnose the problem, but oiling the motor requires that the motor be fully removed from the fan in order to oil the inside bearings.
Old 01-04-08, 12:14 AM
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The furnace uses kerosene.

According to the repairman yesterday there is a pump that pulls the fuel from the tank outside into the furnace and the nozzle on the furnace broke into little pieces, and the repair man replaced it and a thing he called the pump coupler.. this is all new to me.

I found the owners Manuel on-line, and pressed the button for the fan and the fan kicked on and ran fine while I held the button in. So I let the fan run and cool the furnace down.

My mom who owned the trailer before me suggested I go to the fuse box and turn off and then back on the fuses for the furnace.

I did that about 30 mins ago and then manually started the furnace and its been running like normal since and the door isn't getting hot this time, but now I actually can feel the fan blowing on the door....

I also explained to my brother in law what you stated about the fan, belt, and oiling them, he agrees and is going to come over later this morning (after he finishes and do this for me.

What you stated about why it would keep shutting off makes lots of sense and since the door was hot I think that is why it was shutting off.

And now that I hear the fan and know what it is suppose to sound like I can say it wasn't running before.

Thank you for your help and suggestions, I will keep you posted after my Brother in law comes over.

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