Have model md5tpa Pro-com wall heater. heater will not go out with thermostat, you have turn dial off.

need to test thermostat and circuit

Change battery located on back of thermostat??

Go to google
Search for your model number 1234XX .pdf
Add .pdf in search parameter.
Honeywell posts most their thermostat manuals.
Open pdf file, and then Use Ctrl+F for search feature
Word-Search manual

To find model number on thermostat, remove from wall.
Model number appears on back.
Don't forget to replace battery while you have back exposed.
Dead battery can also cause lockout and malfunction

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Get a vacuum cleaner and clean the dust off the bricks is what I would do.

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This heater has both a dial and a wattage selector. The dial is a thermostat, so it will turn the heater on and off as the temperature gets warmer and colder. Just like the thermostat on the wall in a house. The wattage selector switches let you pick how much heat goes in when the thermostat (the dial) tells the heater to turn on.
If you set the wattage at a higher level, the heater will use more power at once, but will turn on and off fewer times to keep the temperature determined by the dial setting.
If you set the wattage to a lower level, the heater will use less power at once, but will turn on more often and still use about the same amount of electricity.
So the dial really lets you pick how warm you want it to be in the room, and the wattage switches let you pick how often it turns on and gets hot. So this dial really determines how hot your room will be.

There are two access panels on the heater, remove screws to access it. They cover the upper thermostat and element and the bottom covers the bottom thermostat and element.
The top thermostat is the main one that has a reset button along with a dial to turn up the heat for the top element. A white plastic knob that you can use a flat head screw driver to turn to adjust.
Also you have one on the bottom to turn to adjust the heat on the bottom.

This is how you adjust thermostat's to increase to a hotter setting.

I have one of these heaters as well. The input/output dials are thermostats.

The higher the input dial is set, the more power the heater draws during its charge cycle (ie the "on" period that is set on your time panel). Which means a higher daily ration of heat, and a bigger power bill.

The higher the output dial is set, the more quickly the heater lets the stored heat out. So the highest setting would give you most of your daily ration of heat during the "on" period but less heat for the "off period... while the lowest setting would give you a relatively constant heat output throughout the day.

visit this page for Lakewood parts and service center info:
http://www.lakewoodeng.com/html/parts.html

If you have an ML300HGA, it is a manual-control heater, which means you turn it on and you turn it off. No thermostat. It does not have an AUTO setting.

Likewise, the thermostat-controlled models do not have a Manual mode. If you have the ML300TBA, it has a thermostat and will turn itself on/off in order to maintain a room temperature.

On manual models, the numbers (if any) on the dial are heat output selections. Set the control to the highest heat setting and that's what it does until you turn it off.

On automatic thermostat models, the numbers on the dial are temperature selections. Set the control to the highest heat setting and the heater will continue running until it is 85-90 degrees, then shut off. Set it around 2 and it will maintain a temp of around 70 degrees.

All Procom heaters are either automatic (thermostat-controlled) or Manual. None are both.

YOU COULD EITHER HAVE A THERMOSTAT PROBLEM OR FAN CONTROL PROBLEM.TURN THE POWER OFF AT THE FURNACE AND TAKE THE THERMOSTAT OFF THE WALL.MAKE SURE YOU MARK THE WIRES SO YOU KNOW HOW TO HOOK IT BACK UP AGAIN.RESTORE POWER TO THE FURNACE.TOUCH THE WIRES THAT WERE HOOKED TO THE R & G TERMINALS ON THE T-STAT TOGETHER AND HOLD THEM THERE.OBSERVE THE OPERATION. WHEN YOU TAKE THEM APART DOES THE BLOWER STOP?TRY IT A FEW TIMES. IF IT CONTINUES TO START AND STOP YOU GOT A BAD T-STAT.JEFF