older coleman mobile home furnace takes forever to heat up then only runs for 30 sec than shuts off then comes back on after 5 to 10 min tired of messing with it if anyone has a cheap furnace for a garage let me know i live in gr michigan

 

Take the gas valve off and remove the burner orfice and check for a spider web.

 

I often see some quite decent furnaces available for free or low cost on Craigslist. Quite a few decent 80% furnaces are being yanked out and replaced by 90% efficient furnaces.

Finding one suitable for a mobile home installation would be trickier, and installing an old furnace about which you know nothing is probably unwise unless you have significant HVAC skills and experience.

Installing the wrong furnace in the wrong way can be deadly. I'd have to recommend against that kind of project unless you have real HVAC skills and experience.

 

Repairing your existing furnace may be practical.

Please post the model number of the furnace which is on the rating plate in the burner compartment of the furnace.

Be a careful observer of the sequence of events that takes place when the furnace is lighting up. Start by turning the thermostat down until the furnace is off, the report the sequence of events you see and hear when you turn the thermostat up and the ignition cycle begins. The more detail you provide the greater the chance of solving the problem.

You may need to watch that cycle several times to observe it accurately.

 

It takes forever to heat probably because it only stays running 30 seconds at a time.

You may simply have some weak thermodisc limit switch, malfunctioning stat, weakened pilot light, bad blower, or something else simple to solve, that is shutting this down and you. No matter what it is, it is bound to be fairly simple and (reasonably)cheap.

If you are around, we can help more, I'm sure.

I am experienced with Coleman and mobile home stuff.