unbreathable air with Odor

[Jay P]

we have central air system with both cooling and heating (the heating is with gas)

when using the central air cooling there is no issue and everything is fine and NO odor, in the other hand when using the heating in the central air system there was an unbreathable air with odor that is resembled a gas smell or burning plastic smell, in the same time there is also unbreathable air with odor that feel like your breathing dust but not neccery dust its hard to describe the smell.

consequently, we called hvac professional to inspect it and according to him the the coil and was getting over heated and was burned which what he belived what caused the gas/buring plastic odor in addition he also said that the furnace have rust and old probably due to a water leak from the AC.

Based on his finding, last Friday he replaced the furnace and coil and installed a new furnace and coil Friday (at least that what he claimed)

since last Friday, so far we haven't incur the gas/buring plastic odor at least for the time being, although I must admit that we barely used the ac heating since that time.

however the unbreathable air with the odor that remind me dust smell persist which make the heating option unusable since we cant breath and smell this.

the speciallist argued that there is nothing els more that he can do and he think it might be a dust issue and there for we should have the air duct proffionaly cleaned.

I should be noted that i toke a picture of the duct and also used an inspection video camera that I pulled in a few feet into the duct into the duct in 3 supply out of 6 and they all looked very clean with minimal dust.

If it is an Airduct cleaning issue don’t you think that the unbreathable air and odor which have been the issue prior to the furnace replacement when using the heating should also accrue when using the cooling?

Or in other-words given the fact that the problem with the unbreathable air with the odor doesn’t occur with the cooling rule out the possibility of a duct cleaning issue?
after all both heating and the cooling circulating the air through the same duct system

any idea what is the issue and how to resolve it?

thank you and I would appreciate your help

 

[keep it clean]

Open your windows. Turn heat on. hold temp at whatever it maxed out at 90° or whatever. And let it cook off for at least an hour. I had to do this with my heater every year. Or it stunk. Would even fill the house with a haze. Which is why i did this just before heating season while still in 50's- 60's . But after that initial fire up it was fine.

 

[keep it clean]

And use good filters. Bot them cheap blue or green see through ones.

 

[Kevin Dumas]

You won't smell dust circulating over and through the ac coils but you will smell the dust burning as it goes over the heat exchanger when in heat mode.

Have the ducts cleaned.