Blower turns on and off after just a short time and repeats many times.

We have a mobile home Coleman mod 7900 furnace, no air cond. The blower comes on and turns off time after time when trying to heat the house up.. Never seems to get the place warm... any help appreciated

Very common problem with Coleman. The bi-metal fan switch needs to be replaced.

First item to check on the heater should be the air filter that is located in the Coleman heaters cover. Sometimes the air filter where ever located in the return air most commonly, This is where the air flow is drawn into the heater and dust and lint are taken out of the air. Do check and see if there is any thing blocking the air flow to the heater such as storage items in front of the heater where the return air vents are located and check and the vents in the conditioned space to make sure that all the registers are un blocked and that the registers are opened in the conditioned space and that dust is not blocking air flow. If the air filters are dirty then do change the air filters with new air filters. This fan cycling off and on sounds like a possible safety issue that needs immediate attention rather than letting the heating unit run while not working properly. These heaters have a verity of safety switches to protect the heater from over heating and preventing fire to the residents home and self. . Use extreme caution if you are not well schooled in heating repair as these heaters can cause fires in the home as well as carbon monoxide poisoning from old rusted out combustion chambers in heaters that have not been taken care of properly. Do check for rust around and in the heater and use caution if you or yours have been tired sleepy more than normal and if you have head aches have the unit shut down as a precaution and checked via a pro.