Ac furnace help

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earthmover

earthmover

in the tire smoke
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Any heat and air guys on here is really need some technical help..went to work last night air condition blowing just fine son calls and say air conditioning stop..I get home this am check things over power is fine thermostat is fine so a buddy tells me the 240/24volt trans is gone I get 1 14.00 back home replace it and hear a pop it's gone..now I thought I had all the breakers off but didn't so that may have blown it..

Now this is what I have checked since ..if I turn my fan on manual it works just fine if I go out side to my unit and put the cover and push the spring control module the air conditioning comes on but it will not come on by the thermostat..any idea of what I need to check..should I just replace the transformer again with all the breakers off ..I mean I know I have to buy another one anyway but don't want to keep buying them if there is another problem..

Thanks for any and all help ..my grand kids had to stay in a 90 degree house last night that's not good lol there only 10months old and cranky lol ..
 
Let's get back to this pop??

First, most /all control transformers are fused, some of them "not obviously." On many (including battery chargers) you can carefully cut into / unwrap the first layers of paper on the transformer, and there's a thermal protection device under there. This is a combo fuse and thermal device, if the transformer gets hot, it will pop

SECOND. IF the transformer blew, "something" caused it. There are LOTS of causes most simple. There could be a "raw" spot in the stat wiring grounding / shorting on ductwork/ piping / a nail. Easy. Cut it loos at both ends and check it with a meter for continuity and shorts

THIRD. "A load" in the controls circuit could be a problem, or othe related wiring. For example, the coil could have gone bad in the contactor in the outdoor unit. "Some" of the wiring might have a problem. It's not unheard of for mice or other rodents to chew on the stuff

"The weird thing" you say the fan works. The fan control circuit SHOULD be using the same transformer, wiring, and so on as the OD unit.

DOES IT HAVE two transformers? Some units have one in the furnace (indoor unit) and a second in the OD unit. Many use one for all the controls

A little "film" on internal transformer protection

 
earthmover said:
Any heat and air guys on here is really need some technical help..went to work last night air condition blowing just fine son calls and say air conditioning stop..I get home this am check things over power is fine thermostat is fine so a buddy tells me the 240/24volt trans is gone I get 1 14.00 back home replace it and hear a pop it's gone..now I thought I had all the breakers off but didn't so that may have blown it..

Now this is what I have checked since ..if I turn my fan on manual it works just fine if I go out side to my unit and put the cover and push the spring control module the air conditioning comes on but it will not come on by the thermostat..any idea of what I need to check..should I just replace the transformer again with all the breakers off ..I mean I know I have to buy another one anyway but don't want to keep buying them if there is another problem..

Thanks for any and all help ..my grand kids had to stay in a 90 degree house last night that's not good lol there only 10months old and cranky lol ..
Click to expand...
Check low voltage wiring from thermostats to out side unit. Check wiring at unit first. You may have a shorted low voltage wire. This will cause the transformer to blow.
 
buddy tells me the 240/24volt t
Click to expand...
So yur buddy was trained by Carnac The Magnificent?
Was the "high" voltage to the transformer 220, or 110? Some indoor units can be 110, some 220; and as posted earlier there can be the transformer inside, outside, or two. Did you check for power before removing the panel? If the unit is 20 years old, or less, the chances of electronic failure are pretty high with pops occuring, unless the stat is a Honeywell T87 or one like it. I'd call a reputable tech instead of parts replacement, it's safer and techs do not appreciate owner fixes to nowhere because that can add problems to the original one.
 
Last edited:
greg r said:
we techs do not appreciate owner fixes to nowhere because that can add problems to the original one.
Click to expand...

Heck I used to love em, guaranteed extra time and money. When I just started out, a tiny outfit in Spokamentro, we'd get 'a call' late Friday afternoon. It would ALWAYS be "some bar" we'd never heard of. They of course had no credit and had tried to stiff some of the bigger outfits, so they tried yellow pages roulette.

You ALWAYS wanted to nail 'em down on the phone, and tell them 'we want xxxx deposit up front.' A couple of times or more were wasted trips. You'd go out there and suddenly the boss "was gone." Well guess what? So was I LMAO.

N' yah, we got stiffed once, for a compressor. One afternoon my boss looked at me, and said, "Why don't you go up there and throw that compressor right off that roof?" (Meaning pull out a brand new compressor we had not collected for)
 
67Dart273 said:
Let's get back to this pop??

First, most /all control transformers are fused, some of them "not obviously." On many (including battery chargers) you can carefully cut into / unwrap the first layers of paper on the transformer, and there's a thermal protection device under there. This is a combo fuse and thermal device, if the transformer gets hot, it will pop

SECOND. IF the transformer blew, "something" caused it. There are LOTS of causes most simple. There could be a "raw" spot in the stat wiring grounding / shorting on ductwork/ piping / a nail. Easy. Cut it loos at both ends and check it with a meter for continuity and shorts

THIRD. "A load" in the controls circuit could be a problem, or othe related wiring. For example, the coil could have gone bad in the contactor in the outdoor unit. "Some" of the wiring might have a problem. It's not unheard of for mice or other rodents to chew on the stuff

"The weird thing" you say the fan works. The fan control circuit SHOULD be using the same transformer, wiring, and so on as the OD unit.

DOES IT HAVE two transformers? Some units have one in the furnace (indoor unit) and a second in the OD unit. Many use one for all the controls

A little "film" on internal transformer protection

Click to expand...



Then unit has 1 transformer that I see.it have a manual switch I can turn my fan on inside the unit..I switched out the thermostat and still nothing..I'm thinking it's the wires the go from the unit thermostat wires ..but no sure..there is no fuse in the wiring as of now but will be when I'm done..
 
zigs said:
Check low voltage wiring from thermostats to out side unit. Check wiring at unit first. You may have a shorted low voltage wire. This will cause the transformer to blow.
Click to expand...


Thanks I'm doing it right now
 
greg r said:
So yur buddy was trained by Carnac The Magnificent?
Was the "high" voltage to the transformer 220, or 110? Some indoor units can be 110, some 220; and as posted earlier there can be the transformer inside, outside, or two. Did you check for power before removing the panel? If the unit is 20 years old, or less, the chances of electronic failure are pretty high with pops occuring, unless the stat is a Honeywell T87 or one like it. I'd call a reputable tech instead of parts replacement, it's safer and techs do not appreciate owner fixes to nowhere because that can add problems to the original one.
Click to expand...



Lol thanks but my brother is a tech been 1 for years but he is at work and live in another town but plan to come tomorrow morning if I can't seem to fix it..he has been on and off the phone with me but I choice not to bother him much while on his job ..as I'm a small business owner and can't do it myself when on my job.
 
earthmover said:
Thanks I'm doing it right now
Click to expand...
The make and model of the indoor and outdoor units, voltage, etc are helpful plus any info on the thermostat. When you changed the transformer, was it the same size in VA as well as the voltage?
 
greg r said:
The make and model of the indoor and outdoor units, voltage, etc are helpful plus any info on the thermostat. When you changed the transformer, was it the same size in VA as well as the voltage?
Click to expand...


OK I'll get it to you ..I'm heading to bed been up all day ..got 2 hrs yesterday before work last night off at 5 got 3 hrs today I feel as if I have been drinking all day lol ..I'm getting old I use to could work day and night sleep 3 4 hrs lol no more I'm done in about 10 total now lol
 
Check to make sure your condensation drain is not clogged and you have tripped the float switch.
Also check to see if you have a moisture sensor in your air handler

Either one of these could cause the symptoms you are seeing.
 
trapster said:
Check to make sure your condensation drain is not clogged and you have tripped the float switch.
Also check to see if you have a moisture sensor in your air handler

Either one of these could cause the symptoms you are seeing.
Click to expand...

Uh, no. This type of thing is not going to burn up control transformers.
 
You are correct I misread his OP, they will however block parts of the system from seeing the 24v ac and will keep the compressor from running.

But it sounds like he has a short, probably outside
 
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