Posted: 6/3/2008 3:38:21 PM EDT
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My two year old 2.5 ton Goodman central AC unit is acting up this Spring. Last week the compressor (outside) would either not turn on, or would stop running while it was supposed to be cooling. The company which installed it came out and checked everything--no problem found (although these units supposedly can have a bad "contactor"). A-hole charged me $110 to tell me "nothing wrong". Last week there seemed to be a burning electrical smell around the outside unit. Today at some point the outside unit cut out again. Indoor unit continues running, but there is a strong electrical burning smell both upstairs (around the air intake for the unit) and in the basement around the furnace/AC evaporator. Worse, the thermostat seems to not control the AC anymore, even when the thermostat is turned to off the indoor portion of the unit (and fan) still run. I looked at the furnace controls and don't see any wires visibly burned or melted. Any ideas what is wrong and what it will take to fix it? |
Thanks...that will be my next step. BTW if it's a bad board, is that part of the AC or is that part of the gas-fired furnace? The furnace is old, but a Carrier and has always been bullet-proof and very efficient. |
Furnace........... If the electrical smell is OUTSIDE by the compressor then its an A/C issue, if you can smell it inside then it'll be a furnace issue. Make sure the furnace isn't firing while the A/C is, I've seen digital [usually] thermostats short internally and juice up both at the same time. |
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It's usually a blower motor when you can smell it inside the house. If the out door unit isn't running that could be a whole other problem. Get them back out there and when they try to charge you another service call tell them to stick it. Parts will be under warranty, but they will charge you labor for the pain and suffering of changing it out. 
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Some smell outside, but major smell inside. I was hoping it was just an overloaded wire or something. I don't think the furnace is firing since it has two cut-offs (one to turn off the gas, a second to turn off the igniter) and I turned both off this Spring. But the digital thermostat going bad is always possible. It's a Hunter brand, and has worked great in the past. |
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Make sure the fan setting on the thermostat is in the "auto" position. "Auto" will make the blower turn on only when the A/C or the furnace kicks on. If it's in the "on" position, the fan will run continuously. The thermostat could also be bad. As far as the burning smell inside, there could be a short on the board(probably a relay if you can't see any charred wires) or the blower might be bad. For the outdoor unit kicking on and off, it sounds like it could be a bad contactor. Check the disconnect (the outdoor fuse box looking thing, it supplies the 240 volts to the outdoor unit) and make sure that is pushed in all the way. It could also be a bad run capacitor. There are so many different things that could be going on and I can't tell you exactly what is wrong without being there. But it sounds like it's originating from the furnace/air handler in the 24 volt circuit. It should still be under warranty. Exploit that to the extreme until the situation is taken care of. Good luck. ETA: how old is the thermostat? |
Yes, the thermostat is in the "auto AC" position, but when switched to "off" the fan (and condenser?) still runs. The thermostat is at least 11 years old. Thanks for the help! And again, when the compressor outside was going off last week there was a burning smell there, today that smell outside was weaker but I could smell it in the pocket where the capacitor and contactor are located. |
Easy to check the cap, just switch over to Microfareds and if it's +-10% it's bad. I'll change them out if they are 5% under myself. Kill power, Remove one of the leads and test. DOn't get poked or discharge the cap first. And it sounds like your thermostat isn't working right either. Moving it to off should kill power to the 24V system. |
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Suprised nobody figured out whats going on here. You have a short in the low voltage control most likely caused by the contactor in the outdoor unit. Chances are the control board insde is cooked. Get those pole smokers back out and blame the whole thing on them. Edit* Ok read above posts and some have got it |
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Here is a dumb question, is it an analog or digital thermostat? If it's digital when was the last time you changed the batteries? I think it's a thermostat issue. Replace the thermostat and turn the A/C on. Make sure the blower in the furnace comes on when you turn the A/C on at the thermostat. When you turn the A/C off at the thermostat, make sure the condensing unit shuts off(the blower fan in the furnace may continue to run for a bit). If everything cycles normally, then the problem is fixed. If the condensing unit stays on after turning it off at the thermostat, turn the A/C off at the breaker. In this situation, it's most likely a bad contactor and you'll have to have somebody come out and look at it. I hope that's not confusing. |
I checked here at ar15.com before buying it and a bunch of people here liked their Goodman units (for the price!). Should have just gone with Carrier, it's all my dad has ever bought. ETA: if it was the contactor which fried the system, the contactor is a General Electric part. |
It is digital and the batteries are fresh. Turning it to "off" the inside fan still runs and the outside compressor will not run under any circumstances. So I have to shut off the furnace/indoor part of the unit at my breaker box. I think your diagnosis is correct though--the bad contactor fried the board on the furnace so the thermostat doesn't talk to the system anymore. ETA: the thermostat upstairs also smells "cooked". Update: yes the installers are indeed pole-smokers. The transformer, furnace board, thermostat and connector are all fried. I believe that it was the connector which set the whole mess in motion (they were out last week after the compressor would not start and I smelled electrical smoke around the connector/capacitor). They insist that it wasn't the connector which caused the problem. So far I am out $400, expect another $400 to get the new board installed. They were kind enough to use this as an opportunity to try to sell me a new furnace. They also wanted to charge me $250 for a new Honeywell thermostat. I'll be calling Goodman corporate soon, and probably the BBB. Luckily my wife is a lawyer and has some experience suing HVAC contractors. Any of you guys in the trades wonder why people don't trust you, companies like this are the reason. |
Sounds like someone deadshorted the system or accidently put 120 or God forbid, 220V on a 24 V line. I will admit to doing it once when I forgot to remove the 120V jumper on a fan limit. It do smoke the pricy parts.
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Update: after replacing most of the controls last week the compressor has died again. It won't start up at all. I've done everything a half-assed homeowner can do to restart it (switched the circuit breaker, checked the inside breakers, re-wired the thermostat). Possible or likely that the new contactor they installed is bad, or something more major? AT least there is no electrical smoke/burning this time. Of course it's Sunday morning and these bozos don't work weekends. I'm considering calling in someone who works weekends, because I'd like a second opinion at this point. |
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This has happened to me twice with my lennox. Try taking the cover off the unit outside to expose the compressor and contacter(the thingy that buzzes) There ought to be a plastic box on the compressor with wires coming out that run to the contacter. Take the plastic cover off of the compressor and inspect the wire connections. These tend to burn off on me, I have no idea why, I figure critters get in there and cause an arc. You could buy new insulated wire connecters at any hardware store. |
| Update: it is running in manual mode. No power on the 24 volt circuit, but the thermostat is good, so some other wire must have been damaged in the electrical short. To get it to run I had to jam down the contactor with cardboard (very, very ghetto) and run the thing via the circuit breaker. |
| You might check the transformer. It is the power supply for the system and usually one of the first items that go when a dead short is encountered. Your thermostat is probably running on battery power since on 24 volt isn't present and the display will die as soon as the battery runs down. You can change out the transformer but whatever shorted and took it out initially is probably still shorted and needs fixed..... and will probably take it out again. You can check the transformer my removing the wires from it and checking for continuity through both the primary (usually black/white heavier wires) and then the secondary side (skinnier wires) of the transformer. You can also check continuity on the contactor coil (skinniest wires) to see if it got toasted too. If you have access to a meter you are definitely narrowing it down. |
The transformer was replaced last week (it was melted) with a new one with a circuit breaker on the top. The breaker hasn't popped. Still waiting for the company to get out here... |
Penis envy? |
Nope, just the dishonest ones. And these guys have an EPA license to do what homeowners apparently aren't supposed to do. Someone who is really skilled, and honest, is worth their weight in gold. |
