Sour Smell???

[George]

I need help. I live in Huntsville, Al. The house originally had a Heil 2.5 ton packaged unit on it. It was a bottom-of-the-line model and about 13 years old. Starting to need too many repairs. I purchased a Heil 3-ton packaged unit last Spring and have really enjoyed it up until this Winter. The company that sold it to us came out and did an inspection/cleaning/etc just before Winter set in. Shortly after (I don't know if it is related to their servicing or not) we began to get this horrible sour smell coming out of the registers.

The system will be running for some time and smell perfectly fine. Then, all of the sudden, the house will be filled with a powerful sour smell, like soured milk, that will practically run you out of the house.

They've returned to clean several times and it didn't help. They came out once more last week while I was at work and did something to it -- don't know what. But for a few days, we smelled nothing but fresh air. The days were warmer than they had been. Then, last night as the temperature dropped again, the smell started returning. Just not yet as strong as it was.

Can anyone offer any help??

Thanks.

[imported_Cooler]

The smell could be coming from the drain line? See if the drain line is tied into the sewer line, or just running on the ground. Also check to see if there is a "pee" trap installed in the drain line.
There is a possibility that if it is tied into the sewer drain line, with no trap, OR with a trap that is drying out on you, that you might be pulling in the sewer fumes when the drain line when you switch back to heat.
Just a possibility

[George]

It seems that my coils, drain pan and whatever else were contaminated by molds and bacteria and the guys who had been coming out to inspect/clean it every time we called with the problem (same guys that installed the unit) weren't properly cleaning it with the recommended biocides.

We contacted the warranty company and they contacted the contractor and had them come out and clean it properly with the recommended biocides a week ago last Saturday and so far no more bad sour smell. The warranty company said that if it returns they will install a special coil that they call a "blue coated" coil or install UV lights inside the unit, whatever we wish.

We'll keep our fingers crossed.

By the way, our unit sits outside on a concrete slab and drains into the side yard.

[imported_Bobby A.]

You can purchase evaporator cleaner from home depot make shure it is the kind that does not have to be rinsed off,also check to see if unit has a p-trap installed see installation instructions that came with unit at time of purchase it would have been inside of service pannel.If a p-trap is not installed when the coil is on the negative side of the blower motor water will sit in the pan and mildew and will not drain properly. good luck

[imported_reyab]

hmmmmm. say george that dont sound right especially after all them cleanings maybe you outta check out your duct work..it may not be your unit