repair and replace HVAC

[gw]

I have a 66000 BTU Nordyne LP furnace w / AC about vintage 1985 Mod# MGHA-0066ABFC-01
It's in a 28x50 double wide, in N. MS.

I used the furnace last spring. Since the temps lately stayed below freezing, I lit the pilot, but the burner and fan did not work. I found a wire nut melted at the line in on the black wire, which is also connected to the off, on, fan, switch. A new wire nut enabled the fan motor but not the gas valve.

The electrical diagram concerning the Normally Open and Normaly Closed switches, and relays: This does mean their state when they are disconnected?

I assume that I have other electrical problems. The old controls have no circuit board or trouble lights.

I have added a new thermocoupling. I have read but not understood the term lockout. I've repaired GE electrical HVAC and have a voltmeter.

This unit should be upgraded to a more efficient unit: what's best fo a moble home closet type?

Thanks for reading and I hope to learn something from anyone.

[Robert]

Hi,

Lockout means after so many tries it will lockout for safety.

Normally Open and Normally Closed refer to their state when furnace is off.

Do you have 24vac at the gas valve terminals ?

Will most likely have to trace test with volt meter the entire heating circuit.


As for what furnace to get, that depends on size needed. Then get one that size that fits in space provided and if gas, rated for mobile home use.

Need to do a Manual J Load Calculation to know size needed. Go to hvac-talk.com and click on HVAC Calc at top tool bar for a good homeowner Manual J .


I do offer a troubleshooting session through email for $20 if needed.


Thanks,
Robert

[gw]

I'll test everything I can.
I think I prefer reading MHR articles to troubleshooting, but I will surely post what it was or hire you to guide me through it. My experience tells me that it's usually more than one thing wrong, and like me the equipment is showing it's age.
Thank you Robert!

[Robert]

You're very welcome,happy to help.


Thanks,
Robert