Oily smell from gas furnace/AC

Posted by Dave Boland on November 2, 2009, 10:10 am

Late last August we noticed an oily smell coming from the central AC.
It is even worse now that heating is on. The furnace is gas, high
efficiency, and was checked by a furnace repair person. The CO emitted
is zero, so I don't think the smell is the result of a cracked heat
exchanger. Any ideas.

Thanks,
Dave

Posted by Tony Hwang on November 2, 2009, 10:19 am

Dave Boland wrote:

> Late last August we noticed an oily smell coming from the central AC. It
> is even worse now that heating is on. The furnace is gas, high
> efficiency, and was checked by a furnace repair person. The CO emitted
> is zero, so I don't think the smell is the result of a cracked heat
> exchanger. Any ideas.
> Thanks,
> Dave

Hi,
Blower motor has capacitor which has oil in it, may be it is
leaking(going bad)?

Posted by Lefty on November 2, 2009, 11:25 am

> Late last August we noticed an oily smell coming from the central AC. It
> is even worse now that heating is on. The furnace is gas, high
> efficiency, and was checked by a furnace repair person. The CO emitted is
> zero, so I don't think the smell is the result of a cracked heat
> exchanger. Any ideas.
> Thanks,
> Dave

How long did you run the AC after you noticed it?? I mean, was it late
season for you and you have'nt used it much since?? I would have it checked
for a Freon (refrigerant) leak. If the liquid line was leaking at (or near)
the metering device in the evaporator, it would do exactly like you have
described, and could continue for quite some time even after it runs out of
refrigerant. You may even notice some oiliness (or dust sticking) at the
evaporator where the smaller of the two refrigerant lines enters. Some
people don't realize this, but some of the oil from the compressor will
circulate with the refrigerant in an AC system, and leaks on the liquid side
tend to show a lot more oil than leaks on the vapor side. There are other
possibilities as well, such as motor going bad, spills into duct boots or
top of furnace, furnace blower eating pieces of a badly clogged filter, etc.

HTH, Lefty

Posted by Dave Boland on November 2, 2009, 1:10 pm

Lefty wrote:

>> Late last August we noticed an oily smell coming from the central AC. It
>> is even worse now that heating is on. The furnace is gas, high
>> efficiency, and was checked by a furnace repair person. The CO emitted is
>> zero, so I don't think the smell is the result of a cracked heat
>> exchanger. Any ideas.
>> Thanks,
>> Dave

>
> How long did you run the AC after you noticed it?? I mean, was it late
> season for you and you have'nt used it much since?? I would have it checked
> for a Freon (refrigerant) leak. If the liquid line was leaking at (or near)
> the metering device in the evaporator, it would do exactly like you have
> described, and could continue for quite some time even after it runs out of
> refrigerant. You may even notice some oiliness (or dust sticking) at the
> evaporator where the smaller of the two refrigerant lines enters. Some
> people don't realize this, but some of the oil from the compressor will
> circulate with the refrigerant in an AC system, and leaks on the liquid side
> tend to show a lot more oil than leaks on the vapor side. There are other
> possibilities as well, such as motor going bad, spills into duct boots or
> top of furnace, furnace blower eating pieces of a badly clogged filter, etc.
>
> HTH, Lefty
>
>

Thanks Lefty and Tony,

We noticed the smell late August. No problem before that time. The
performance of the AC system seemed ok, so I didn't suspect it. The
problem is continuing into the heating season. I made arrangement for a
factory trained person to stop in and I will mention everything the tow
of you have suggested. Thanks again!

Dave,

Posted by ransley on November 2, 2009, 1:25 pm

> Late last August we noticed an oily smell coming from the central AC.
> It is even worse now that heating is on. =A0The furnace is gas, high
> efficiency, and was checked by a furnace repair person. =A0The CO emitted
> is zero, so I don't think the smell is the result of a cracked heat
> exchanger. =A0Any ideas.
> Thanks,
> Dave

Maybe you are smelling mold

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