The septic company came out and did an inspection on our system that we purchased from them; it turns out the compressor wasn't working, so they replaced it under warranty. I'm still new to the whole septic world and still learning; when they replaced the compressor, which I believe generates air bubbles, our whole house started to smell.

Like a waste treatment plant, and it didn't smell it at all down by the septic system or at least not to the amount it does inside our house.

My question is, what in the heck could be causing the vapors to come into the house?

How long was your compressor not functioning? System may have reverted to anaerobic if it wasn't working for 1-2 weeks. When compressors go out, the aeration stage stops and bacteria growth slows down. This all but stops waste breakdown in an aerobic system.

Yea, we tried that already, We did a full system flush with all the water faucets running, and it didn't help.

My guess it's been out for months, apparently, the alarm was muted which I had no clue it could do that. Now I know what to look for when I talked with the septic company.

We have only had bad odor from the septic system outside the home when the aerator compressor failed, the air line popped off or when the aerator became clogged. The beneficial bacteria in the holding tank die off and the discharge water is not completely treated. Never had the sewer smell inside.

This link might help: SEPTIC SMELL IN YOUR HOUSE? 5 CAUSES OF (AND SOLUTIONS FOR) SEPTIC TANK ODORS

P trap with no water in it or a wax ring leaking

This time of year its very common to have a dry trap in the hvac system.

The house doesn't smell anymore, so that's a good thing; I believe the issue is from the toilet wax ring; it's the one that came with the toilet. Considering how much our GC was sucked a$$, it probably wasn't installed correctly, so I'll be removing all three toilets this weekend and putting a better wax ring in them.

Update:

Changed out all the toilet wax rings and replaced them with better silicon/wax rings. I thought the house was smelling better until I walked in last night and still have a sewer smell.

I've ordered a silicone gasket to put on the washing mashing discharge hose to plug the hole; I know that the pipe leading out to the sewer doesn't have a p-trap. The only other thing I can think of is the tube/shower wasn't installed with a p-trap.

Would it be worth putting a big p-trap on the mainline going to the septic?

Update: for those that care!

Nothing I did seem to work, and the house still smelled terrible; I asked the wife to start gathering the funds to have a Plummer come in and figure out what the heck is going on.

I knew it had to be a venting issue so I got up in the attic hoping I a vent pipe just came to lose or something, as I'm searching and tracking all the pipe, I notice a piece of pipe coming out of the wall from our professional kitchen (half our house is a 2bed/2bad and other half is a professional kitchen, not finished yet).

As I'm getting closer, mind you I'm a big man, so it's not easy, I notice the smell is getting stronger and stronger. Sure enough, it was a vent pipe from the house's kitchen side, which is connected to another part, but this part wasn't, so I caped the end, and the house is normal now.