Mysterious house smell

[SecondCor521]

For those of you keeping score at home, I'm frugal.

In the last week or two I have noticed a mysterious smell in my house.

It's not me; my grooming habits continue as they always have, and my ex didn't mention BO in the divorce complaint.

It is a "fumey" sort of smell. It vaguely smells like latex paint or plastic.

It seems to give me mild headaches. It may be giving me a slight tickle in my throat.

It is not the smell of natural gas or propane.

I don't think it's radon because I think that is odorless.

It is throughout the house (or at least the first floor; I don't usually go up to my son's "bonus above the garage" bedroom). I think it is also in the garage area (I haven't gone in there much lately because my garage door opener is coincidentally broken).

I suspect it may be my air conditioning unit, although I don't know why. I've had my A/C on for several weeks, so the onset of smell might have coincided with that. The A/C is working OK, although it has been "short cycling" for a while now where the A/C will come on for 30 seconds, then go off again. It's a central forced air unit that is probably a standard efficiency unit. The unit is probably about 6 years old. I have not had the unit serviced in the ~4 years I've lived here. Weather lately has been in the 90's; I keep the thermostat at ~75-~80. Automatic thermostat also seems OK.

Any ideas what this might be from some of the more experienced house folks on this board? I'm glad to provide more data if necessary. I have an innate distrust of A/C & heater repair guys.

2Cor521

 

[bbbamI]

Mildew in your A/C evaporator perhaps?

 

[Telly]

Your A/C or thermostat needs work. There is no reason the A/C should turn on for 30 seconds then turn off. Furthermore, if your compressor turns on again within a few minutes of it turning off, that is very hard on the compressor. A/C systems need sufficient time off, after they turn off, for refrigerant pressure to equalize across the compressor. Otherwise, the compressor has to start up against the head pressure, drawing a lot of current, stressing the compressor's electric motor, stressing motor start circuitry, and running high current on the contactor.

As for the smell, people describe smells differently. It is possible you have mold buildup on the A/C evaporator core, or in the evap cabinet. Also should check that the A/C condensate drain is flowing when the unit is running. Should see a trickle of water running, unless you live in a desert location where humidity is very low (but then would expect the mold possibility to be low, too).

Does your house seem to be damper than it used to be?

 

[Htown Harry]

Search mission ideas:

1. Changed the intake air filters on the A/C recently? I had a peculiar A/C smell in a car recently that was fixed when I changed the filter.

2. You didn't say where the A/C unit was located. If in the attic, take a trip up during the day when it's working hard. If the fan unit or the condenser is the source of the smell and sending it through the ducts, you may get a strong whiff standing next to the unit.

3. If you have closed cabinets or storage bins in the garage, spend a few minutes going through them all. An old can of paint thinner on the back of a shelf can rust out and send it's contents slowly spilling out through a pinhole.

 

[ERD50]

A 30 second cycle is *very* short indeed. It may or may not be related to any odor, but it isn't right. If you are handy, you could probably rule out a few things before calling someone.

Is the plastic smell like hot, burning plastic? Could be something overheating in that A/C.

I've had problems with my blower fan stalling on about four or five occasions over the past 10 years. It overheats some parts in the control box, and that smell gets carried all through the house since it is in the vent, so it is hard to pinpoint.

-ERD50

 

[Stevewc]

You might try to set the T-stat down a little lower.
Then see if the actual temp in the house drops to that setting.
If not the unit probably needs attention.
Sounds like it might be low on freon if it cycles to quickly or will not lower the temp in the house as it should.
Also if the house has a crawl space or basement with the unit under the house you can easily pickup a earthy smell through the duct work.
Just Random thoughts,
Steve

PS. As ERD50 points out if its an electrical or plastic smell someone should really look inside the unit and check things out.

 

[SecondCor521]

It doesn't smell mildewy to me, but it's a possibility.

When I said 30 second cycle time, I think it's actually the blower fan in the garage that is cycling that fast. The A/C unit itself is on a small concrete pad outside the house, just outside the garage.

House does not seem damper than usual.

Boise is a very dry climate -- it's essentially a high mountain desert.

I've changed the air filter in the furnace thingy (sigh) in the garage. I've never messed with the unit outside; didn't even know it had filters....

Doesn't smell like burning plastic...more like the smell of brand new plastic water toys (like that plastic they make water wings out of) or new shower curtains when they off-gas.

I set the thermostat down to 75 and the A/C turned on and got the house down that cold after a short while.

The house does have a crawl space and an attic, but as I said above the A/C unit (fan and condenser (?)) is outside the house. The only thing going on in the attic/crawl space is the duct work...at least I think so, I've never been in those parts of the house...

Thanks for all the input; I'll check into them some more before I call anyone.

2Cor521

 

[happy2bretired]

When my doorbell got stuck and blew out (I don't know how else to describe what happened) I could smell what I call an ozone smell in the room. It was my doorbell box thing overheating - I could feel the heat when I placed my hand on it. That smell gave me a slight cough-tickling in my throat.

Turn off the A/C and have it checked.

PS: check your door bell too?

 

[Stevewc]

I don't think you will find any filters on the outside unit. But it is a good idea to clean those coils once a year. You can do a pretty good job with a little water pressure. They also make a coil cleaner solution.
The location of the blower is what I was referring to. If its located under the house or even the duct work is under there it can pick up some earthy type odors. May not be your problem but a possibility. Kind of hard to trouble shoot without being there to do a process of elimination.

If the unit stayed on and cooled the house down that's a good sign/report.

I do know there is a thermal type switch in the furnace/blower that controls when the fan blows while in the heat mode. Doesn't allow the fan to blow until the firebox gets somewhat hot. The same device will keep the blower going after the fire cuts off and allows the box/metal to cool a little. The main reason for all this is to keep cold air from blowing into the house while in the heating season. A few years ago I had this switch go bad during heating and my fan did cycle way to much. I'm wondering if this device could be causing your weird cycling. But I'm not sure it is supposed to even do anything during cooling season. I would think it should be overridden during cooling. But if it were bad, not functioning properly who knows? I guess stranger things have happened.
Keep in mind you also have a cooling coil just past the blower unit. That coil could also need cleaning. As a matter of fact you have me thinking about cleaning mine when the weather is cooler. That particular coil can be difficult to get to. Might have to disconnect the duct work to do a really good job. Or maybe try to get to it through the blower unit.
Oh Well, just trying to give you something to look into or think about.
Didn't mean to write an owners manual.
Steve

 

[ERD50]

Keep in mind you also have a cooling coil just past the blower unit. That coil could also need cleaning. As a matter of fact you have me thinking about cleaning mine when the weather is cooler. That particular coil can be difficult to get to.

Not to hijack this thread toooooo much, but...

Has anyone gone in and cleaned that coil? I've never done mine, and it sure couldn't hurt to check it (well, assuming I don't poke a hole in it in the process). Mine is in the ductwork above the horizontal/upflow furnace. I don't see any access - I was thinking about just cutting (carefully) a big square section out of the duct, and then covering it with a piece of sheet metal when I was done. It's not hard to get to, it's out in the open pretty much and right at shoulder height, there just isn't any access panel or easy to pop-off duct section there.

-ERD50

 

[ERD50]

Not to hijack this thread toooooo much, but...

Has anyone gone in and cleaned that coil?
-ERD50

OK, in the mean time I googled that for myself, using these terms:

air conditioning coil cleaning indoor|inside|evaporator (the "|" symbol is the same as "OR"), too many hits on the outside coils.

This one was pretty good -

How to Clean Air Conditioner Evaporator Coils - Part 2 | HandymanHowto.com

You need to get in from the 'top' , away from the blower. Spray the cleaner in which is designed to cling and then drip down and out the condensation drain.

I think I could get a look at it from the humidifier duct, and actually, I could probably remove the whole section of duct above it and get a really good shot at it. But as long as it is working, that will be an October job.

-ERD50

 

[Stevewc]

ERD50,
This thread got me to thinking about the need to clean mine too.
I've never cleaned the one in my home unit or any home type unit.
I have cleaned larger commercial units though.
I would have to look at mine to see how hard or easy it is going to be.
I think as long as you don't flood your furnace/blower or home it would be a good idea to clean once in a while.
If it works out so any water or chemical goes in the condensate drain that will be exactly how the commercial units work.
Steve
PS. I totally agree on a cooler weather job.
One problem, I have a long list of wait until its cooler jobs.
Wonder if it will be to cold then? Excuses Excuses !!!

 

[Dimsumkid]

The title of this thread intrigued me. I think this thread has gone off on a tangent quite a bit. I'd be curious to know since it started to happen in the last week or two...have you purchased anything new or brought in any new items into the house in this time frame? Moved anything near the air supply of the AC unit, i.e, chemicals, paints, fertilizers? Is this located on the 1st floor or is there a basement? Buy a new memory foam mattress? Paint recently? Has it been raining a lot in this time period?

 

[BigMoneyJim]

My first thought before reading the whole post was that it could be an unused drain where the water in the P trap evaporated enough to allow sewer gasses into the house, but that doesn't sound like the smell you describe. (Fix is to run water through seldom-used drains.)

The smell you describe might be melting/overheating electronics of some sort. PC power supply, fluorescent balast (CFC or traditional), TV/VCR/DVD, etc.. Possibly even melting electrical wire insulation or connectors inside a wall (fire hazard!). That would usually be at a switch box, but it could also be at a standalone junction box.

 

[DallasGuy]

Have you checked your heating and cooling vents in the attic as well as the furnace in the attic where the furnace fan is to see if they have any leaks and could be pulling in air from the attic? In my case, I live in a neighborhood where the lots are small and houses are close to each other. If my neighbor uses his outdoor grill which is only 5-6 ft from the side of my house, the grill smell will go up into my attic through the soffit vents. Then when I turn on my furnace fan from with the A/C unit, I get faint grilling smells through my vents because my venting and/or furnace is not completely air tight and sucks some of the smells into it. Very annoying. Anyway, are there any outdoor smells that could be going up into your attic and getting pulled into the venting? Just a thought...

 

[TromboneAl]

Organic smells can masquerade as different things, so something that smells "fumey" like a solvent could actually be something completely different. That's why I'd consider a dead animal in the walls somewhere.

Your sense of smell is probably much better than you give it credit for. Pretend you are a bloodhound, and go around the house systematically sniffing different places. You may be surprised to find that you can indeed locate the source of the smell. It might help to air out the house, then close it up, then do your sniffing.

I was able to replicate what Feynman describes in his book:

Amazon.com: Surely You're Joking, Mr. Feynman! (Adventures of a Curious Character) (9780393316049): Richard P. Feynman, Ralph Leighton, Edward Hutchings, Albert R. Hibbs: Books

 

[calmloki]

If you have a crawl space there is a chance that you have a supply or drain line leak under the house. Kitchen drain leaks are very nasty smelling after a few weeks... Look and/or sniff at the vent holes.

After finding a kitchen drain leak and repairing it and getting rid of as much water and muck as possible i rigged cheap box fans to suck from vents on the downwind side of the house - got rid of the smell inside the house within hours, left the fans running 24/7 till the crawl was fully dry.