This unit is a gas 120,000 btu garage/shop ceiling mounted gas heater it was working fine now it lights instantly comes to temp fan turrns on but within 10 to 20 secs the whole unit shuts down gas cuts off and fan also if you cut the power off then on it goes thru the same cycle it is a Dayton model#3E370

SOURCE: Mr. Heater Natural Gas Garage Heater - 45,000 BTU.

my garage heater was working early this winter. I turned the thermostat to 0, but when I went to restart heater nothing happens, can you help me with this problem?

SOURCE: Have 30,000 btu Dayton heater m#3e3665 when reaches temp. fan

Hi blow heater out with air line flame sensor could be dirty check out pressure switch jump this out see if it lights

SOURCE: Just bought a Dayton electric heater to heat a 12'

If it sounds like the fan is hitting something, It is likely you will have to get a step ladder, and look closely at what is making the noise-
Likely something fell in there-- and needs to be removed.

When you shut the thermostat down, does the fan stop instantly?

Mack B