Coleman thermostat clicks, no heat, blower won't go on auto

[snowbound]

Hi, We have a Coleman Presidential Series Gas (propane) Furnace Model 7956-856 in a mobile home. During a power outage last night when trying to hook up to his small gas powered generator, my husband accidentally back-fed (more than once) to the electric panel by way of the furnace -- ouch -- b/c he could not remember how he wired the furnace in the past.

Transformer was hot.

The thermostat clicks. The blower only goes on if it is turned on manually. No heat comes on. Pilot is fine. I recently cleaned the burner. Reset not tripped on housing.

So basically we turn the power on (electric is restored now) and we aren't getting anything. Before we got a hum in the switch. Now, nothing. But the blower will run when turned on manually so the furnace is getting juice.

We were able to get a Honeywell Universal Transformer. Still no change. And we think / are pretty darn sure we hooked it up correctly.

Then we were able to get a universal low limit switch -- the one that the grey and black wires go to. Still no change.

An HVAC guy looked at the relay switch for the Heat/Cool and said it "looked fine" - not discolored. We noticed that this switch does not click when the thermostat is kicked though.

We are snowbound and cold. No one can get in here to look at the furnace. We have a few hours to search for more 'universal' parts.

Any help would be appreciated. We're not sure what needs replaced. There is another relay for the blower that we did not replace. Should we try to get one? And also a "Therm-o-disc" limit switch -- two orange wires -- that the HVAC guy did not give my husband. Should we try to get that one?

Any other thoughts?

Thanks!

[Robert]

Hi,

Will read over your post and reply as soon as I get my diabetic self some lunch. Just getting on here for today.



Thanks,
Robert

[Robert]

Hi,

Sorry for delay, computer went haywire while my wife was using it. Anyway, with what was stated, it really needs to be inspected by an hvac tech.

Buying universal parts is not wise as it is very easy to buy and install parts that are not compatible replacements.

Several components may have gotten fried during to electrical miscues and those need thoroughly checked for safety.

If an hvac guy looked at the relay, why didn't he troubleshoot, find problem and resolve.


This is not a situation to be safely handled here or DIY.


Take care and best wishes,
Robert