mobilehomerepair.com

Hello,

I have a Coleman Evcon Presidential Model #3500A920
Serial #049290953 70,000 BTU Electric Furnance with Nordyne AC cooling coil.

I had to replace the fuse/disconnect because of a burned connection. Inside the control box, the 24VAC (40VA) transformer only outputs about 10 VAC. One wire goes to RC the other one goes to a relay. So I guess I need to replace the transformer and I need the part number for it. There is a terminal block inside with 120 VAC to all connections. If I need to check anything else, please let me know. Thanks for any help with this.

Herb Nance Rosharon, TX

Hi,

Transformer # 3300-3861 can be seen and ordered from right side:

http://www.mobilehomerepair.com/ColemanAC.html


Where is the terminal board, is it at top of the a/c control box ?


Thanks,
Robert

Yes....the terminal board is at the top of the control box. It looks kind of like your part# 3500-5841B. However mine has a 5 wire terminal board.

Yesterday I replaced the transformer with one from an AC supply store. It had all the same specs as the old transformer. I wired it back the same way. It made a loud buzzing sound, then a loud pop and then smoke. I hope I didn't mess something else up. I may have to replace the whole control box....but I might get an AC repairman out.

The furnace does have other issues which I can fix. The condensate pan from the cooling coil has leaked water out and the whole thing is setting offcenter and dropped down about 3 inches. There is a gap at the top to the duct work. I know I have to be aware of cables, wires etc. I was planning to "sure" it back up into place with some 2 X 4 framing.

This is a '93 model Oak Creek double-wide. They used pieces of dry wall the shim the furnance in place.

This is a great forum and thanks for your help.

Herb

Hi Herb,

Most likely fried the transformer. Whatever fried the original one was still there and immediately fried the replacement.

If/when you bought the transformer from us, was going to tell you to go to an auto parts store and get an Automotive ATC 3 amp fuse and fuse holder.

Then, install it inline in the power wire to transformer to guard against a repeat blow out of new transformer.


Before replacing control box, need to find the short or whatever is causing this problem.


May be best to get an HVAC Tech out to save $$$$$ from future parts damage.



Thanks for inquiring,
Robert

Thanks Robert, That's a great idea about the automotive in line fuse. I'll get a service tech out and I'll make a 2 X 4 frame underneath. I'll post a reply in the next couple of weeks and I'll let the forum know what the repair was.

thanks again

Herb Nance Rosharon, TX

Hi Herb,

You're very welcome. Be very careful moving the A-Coil and drain pan, refrigerant lines are easy to break and that is illegal and could be a high fine if caught.

The pan just needs a slight slant and a small couple of wooden wedges placed at back of pan work great.


Did ya notice the local hvac supply sold ya the transformer, BUT never said a word about the inline fuse for protection ?


That's where we seperate ourselves, we don't just sell the parts.



Take care and best wishes,
Robert