I have an Intertherm MGHA-070 that is taking a very long time to come up to temp due to the blower fan coming on for approx 3 min. and switching off for about 30 seconds and keeping this cycle continuously and causing the burner to run constantly. I found a post from a year ago where HVAC1000 states it is the fan switch needing replacement. This was easy to find on the wiring diagram so I will change it out tomorrow. In his answer HVAC1000 mentioned that installing a larger blower motor will help move more air eliminating issues with air restrictions. Will it also make the furnace more efficient by moving warm air into the home faster so the burner is on a shorter time? Would it make enough of a difference to make it worthwhile to buy the larger fan?

In his answer HVAC1000 mentioned that installing a larger blower motor will help move more air eliminating issues with air restrictions. Will it also make the furnace more efficient by moving warm air into the home faster so the burner is on a shorter time? Would it make enough of a difference to make it worthwhile to buy the larger fan?

Mobile home duct systems are VERY restricted but under normal circumstances going to a larger motor is only needed in case of A/C problems. If you blower moves the heat around now you should be OK.

Parts for your system are available here. I know these guys and they are mobile home professionals. Post under the Nordyne list with your questions and they will reply to you. They have parts which might be hard to find. Nordyne ,Intertherm are the same.

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Thanks for the quick response and the contact info.

Thanks for the quick response and the contact info.


Make sure to change or keep your air filter clean at all times on mobiles.

One thing else I should have mentioned is gas pressure.

Having low gas pressure going to the burner (s) can also cause a fan to short cycle since the furnace is not running at full BTUs. If you have access to a pressure tester the label on the furnace will tell you the correct pressure. Natural gas usually 3.5 Propane usually 11 in water column.

If you do not have access to a gas pressure tester you can do the heat rise method. Take a thermometer and read the return air temp. Do the same on the discharge air temp. usually on the furnace label it will tell you what the heat rise range should be.

There are so many different items that can cause the same problem that one is picked and the other forgotten during posting. LOL

Always becareful if you are messing with propane.

Thanks again hvac 1000. It was just the fan switch. It was $14.00 and about five minutes to replace and we live so far into the boonies that it would have cost $150.00 just for the repairman to drive to our place. Right now there is no way I could have swung it and we would be getting by with a space heater. Now thanks to your help we have a warm home again! Merry Christmas to you and yours!

Glad you got it going. Have a great Christmas now that you will be warm.