transformer issues

[yorkamstd123]

im no diyer, just ran that call today and the problem was in the contactor. 1 year old unit. now i will figure out how to apply for pro.

[m-cooling]

What kind of problem in the contactor?
How'd u find it?

[beenthere]

Get your post count to 15, and apply.

Much better answers when you ask questions in the pro tech forum.

[hvaclover]

What you say is very likely true.

But look where the OP said that the 5 amp fuse was not blown. A short on the contactors sufficient to cause an evidently rapid transformer pop out would have surely put more than 5 amps in the low circuit.

That leads me to suspect that he has a "minor" short, causing under 5 amps of current, and that it was just a coincidence that the tranny popped shortly (no pun intended) after he turned on the AC.

Would have to say that would depend on how the loads are distributed on the board.

Consolidated furnaces had no fuse on control board. They would sacrifice the xfmr in case of a short. Makes sense since an xfmr is the least costly part on a furnace.

Had one go on me late last winter so i replaced it and added a mini breaker.

[ECIndHVAC]

Consolidated furnaces had no fuse on control board. They would sacrifice the xfmr in case of a short. Makes sense since an xfmr is the least costly part

BTW, you have mentioned Consolidated & Texas Furnace a few times. Do you use these furnaces?

If so, have you noticed that the Honeywell board on these things is prone to burn up at the blower relay? And have you found out what causes this, or how to prevent it? It seems like it's always the solder joint in one particular location. I've resoldered them before, and they work at the shop, but I'm kinda afraid to put them back on in residences.

The 80% furnaces have moved away from this board, but the 90%ers still use them.

[Bowtye8]

Contactor sounds like likely suspect but I would still check the low voltage wiring. Could have a nick on the insulation.

[hvaclover]

BTW, you have mentioned Consolidated & Texas Furnace a few times. Do you use these furnaces?

If so, have you noticed that the Honeywell board on these things is prone to burn up at the blower relay? And have you found out what causes this, or how to prevent it? It seems like it's always the solder joint in one particular location. I've resoldered them before, and they work at the shop, but I'm kinda afraid to put them back on in residences.

The 80% furnaces have moved away from this board, but the 90%ers still use them.

Used to be one of the highest volume dealers in Mi for them in the 90s.

Can't say as I have ever tried to repair a board. WaYYYY too much risk on liability.

I sling Nordyne now but volume ain't so good. Bad times in Mi sorry to say.

[ECIndHVAC]

Used to be one of the highest volume dealers in Mi for them in the 90s.

Ever deal with Bill Holman? or Francis Frank?

[hvaclover]

Ever deal with Bill Holman? or Francis Frank?

Never heard the names. sorry. used to buy my furnaces from UEP.

[JWB]

Had same thing. Bad reversing valve coil. New short ones don't fit the old units. Get on from the scrap pile or have fun replacing the whole valve.