I have a five year old Coleman Evoc BGU10016A and has four green flashing light which I know is limit circuit open. I just had someone come out and clean my ducts,chimney and furnace and still the same. I replace the three roll out switch and the limit switch and nothing. The onlything it does is blow coold air. The blower motor never shuts off and the vent motor never comes on when it suppose to. The only thing now to do is to see if the vent motor actually workes but don't know how to or the transformer. I did replace the run capacitor. Has someone outthere has had this problem before if so how did you fixed it. (HELP)

You say you have replaced the three roll-out switches and the limit switch, but have you checked the auxiliary limit switch? Usually located on or near the main blower housing. Sometimes it can be hard to see without getting in there with a good flashlight and really searching.

All of the limit switches, including the roll outs, should be wired in series. If you disconnect both ends & use either an ohmmeter or continuity checker that should tell you if a limit is actually open or the control is bad.

I have replaced the auxiliary switch. The burner does come on and after a cuople of minutes I hear the click for the vent motor to come on but it doesn't. After that everything shuts off except the chimney blower and the four flashes comes on again.

Okay, by "vent motor" do you mean the main blower that circulates air through the ductwork? If so, this is the main blower motor. The "chimney blower" is called a draft inducer. This is the blower that exhuast the combustion byproducts to outside. So it sounds like the main blower is never coming on? If so, you need to check for power to the motor when it should be running. If you have power (and you have already replaced the capacitor) you will need a new blower motor. If you don't ever get power to the motor, you will need to replace either the fan relay, or if the relay is on the control board you will need to replace the complete control board.