Unit heater fan won't shut off

[Dingo54]

Hi everyone,
I've lurked for a few years on GF and I've really enjoyed the advice and discussions. I'm hoping to get some help on a problem I'm having with my Empire unit heater (Model UH-1075-1 FSP). For the most part it works fine - it responds to the thermostat and the burner fires up when I turn the Tstat up and the burner shuts down when I turn it down. The problem is the fan runs all the time. To get around this I have it wired to a switch to turn the fan on and off. When I want to heat my garage I flip the switch to turn on the fan and set the Tstat at my desired temp. To shut it down, I turn the Tstat down, wait for it to blow cool air, and then shut the fan off.
It's probably something simple but I'm not sure where to start troubleshooting. Any advice would be appreciated.
Thanks.
Don

 

[The Cobbler]

is there a fan control on the unit or stat that is set to fan on?

 

[AP514]

Fan could be set to "ON" instead of Auto..check to see on thermostat

 

[Dingo54]

There isn't a fan control on the stat. The wiring diagram shows a "fan control". I'll have to open it up and see if it is set to on.
Thanks!

 

[Dingo54]

I don't see an on/off switch for the fan on the stat

 

[acmikee]

probably your fan control contacts are stuck

 

[Milton Shaw]

Looks like a 2 wire thermostat, so no fan control on tstat. Look at the temp thermal controls on the unit itself and check if they are working or miss- wired. Those should give fan delay on turn on so they blow hot air to begin with, and then run for a minute or so after burner off to cool the heat exchanger down. There are usually two, one for fan control and one as a temp safety cutoff, usually located near the top of the heat exchanger.

 

[klassenl]

The wiring diagram shows a "summer switch". Have you tried flipping it.

 

[Dingo54]

Thanks everyone for the suggestions. The limit and fan switches are all accessible through a small cover on the left side (#s 39 - 41). The exploded view of the unit doesn't show a "summer switch" but I'll see if I can find it to determine whether it is set to on or off.
Thanks again!
Don

 

[Bills Tools]

The fan control limit on this unit, have a temperate dial, that turns as it heats up? If so many those temp activated fan control has a push button jumper. An auto or manual run fan feature.


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[Tre900]

my unit has a timed run after the heat has completed to ensure the exhaust and temperatures are low before shutting down. Have you tried timing it or are you saying it NEVER turns off?

 

[Dingo54]

It never shuts off unless I shut off power to the unit. I haven't tried timing it - didn't know that was possible. I also don't see any switches that are adjustable. I'm thinking about replacing the fan switch (#41).