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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a lsc 35 wallount natural gas heater gas works but

Customer Question

I have a lsc 35 wallount natural gas heater gas works but does not turn fan on when I turn fan switch on it just hums I unugged wire from limit switch or thermostat and it still hums I can find zero information about this type of heater
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


Tell me please about how old the heater is, then remove the service covers and take a photo of it from 10 feet away so that I can see the layout, then take a close up photo of the gas valve, **looking down onto the TOP of the gas valve, I need to see the knob and any wires attached.

You can use the paper clip icon at the top right of your tool bar, or the 'attach files' link to the left of your send button.

we can go from there without a time limit.

Expert:  Phil replied 1 year ago.

If there is a wiring diagram glued inside the service panel I can use a well focused close up of that as well.

Expert:  Phil replied 1 year ago.

If the fan just humms, that means there is power to it, and that the fan motor is likely bad. The wiring diagram will tell me if you have a fan motor that uses a 'run capacitor' or not, if it uses a run capacitor, then it might be bad (a $7 part).

We can go from here without a time limit

Customer: replied 1 year ago.
It looks as though something signLs the fan to turn on that is not hPpening problem is I can not find any information on this model lsc35 module wall unit
Customer: replied 1 year ago.
I thought maybe you would be familiar with this model or could tell me where I couldget parts for it but looks like that is not the case
Expert:  Phil replied 1 year ago.

Hello again, these all operate on pretty much the same principles, and about 90% of the parts are off the shelf at the time of manufacture, most parts are or suitable replacements are available.

With over 100,000 heaters on the market, the most experienced man would have seen maybe 1 percent of them, yet we all manage to fix all of them. Its a bit like nails in a flat tire on a car. You do not need to have experience fixing flats on all of the thousands of different tire brands etc,

The fans are controlled from a sensor attached to the furnace heat exchanger, when the sensor gets hot it puts power to the fan... there are very few exceptions with wall furnaces in that regard, if your thermostat includes a FAN switch, then you could run the fan by itself with no heat,

Expert:  Phil replied 1 year ago.

A wiring diagram would allow me to mark it up with trouble shooting instructions and show you how t find the fan limit switch.... and see if your furnace motor uses a run capacitor, 98% of them do not use a fan run capacitor.

Expert:  Phil replied 1 year ago.

Sears used to carry that brand, however the surefire way to get parts is online from a furnace parts house.

a few phone calls will get you a new fan motor or other part in most cases,

This outfit can usually get those parts

If that fails I can go digging through my library of obsolete parts dealers and most likely dig one up for you.

Second level options are to remove the fan motor and take it into the worlds largest stock of hard to find fan motors, Grainger Industrial Supply. The odds of you finding a fan motor are in the 99% range.

Let me know if you would like me to continue working with you or not, we can go from there,