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Heating, Air Conditioning, Fridge, HVAC/Reznor Shop heater will not heat up


I have a reznor model OUH 140 shop heater [diesel].  Fan turns on but heater does not ignite.  Circuit from wall thermostat is Ok.  I've pushed all the reset buttons no help. The fuel pump starts but turns off.  The supply tank has fuel and the fuel filter is Ok.  Any thoughts on what is the problem?  Thanks.

Hi John, The fan should not come on until the burners have been on for say a minute. First we need to check the Honeywell fan/limit switch. If you have a voltmeter, place the meter on N2 and 5 on the terminal block, you should have voltage there. If you have voltage there, then place the meter on 12 and N2. If no voltage there then the the fan/limit switch is bad.

Let me know what happens.


Heating, Air Conditioning, Fridge, HVAC

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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