Headache from AC system
 

Hello,

So this is going to sound like an oddball question.

Last September, I started a job where I'm in my '98 Civic Hatchback most of the day. I was coming home with crazy headaches. I then had my cracked manifold replaced. Basically, pretty much the whole exhaust system has been replaced within the past couple years. I thought it was the exhaust fix that fixed my headaches. In late 2013 when it started getting cooler, I stopped using the AC around the same time the manifold was replaced.

Role into Spring 2014. The past week I've been using the AC a lot because of the heat. The headache have been coming back. Today I noticed the headache coming on pretty strong. It's the same type of headache I was getting last year when I was using the AC. I rolled down the windows and turned off the AC. I noticed the headache subside after and hour and a half or so.

Question: is it possible to get headaches from my AC system? If so, what do I need to do? It's getting hotter in St. Louis and my job requires that I'm in the car 5 days a week most of the day.

I used the heat most of our very cold winter. No headaches from that. Sometimes when I turn the AC on I can smell a faint "stale cocoa powder" smell. I realize this sounds crazy but would appreciate any help.

Check again for exhaust leaks. Block the tailpipe with a rag while the engine idles. Pressure should build up quietly. If you hear hissing under the car, there is a leak (with a big leak, pressure won't build up at all). The only "normal" leak is the two small "weep holes" in the end plates of the muffler. Leakage anywhere else needs to be repaired.

If it's not exhaust, you could try removing the fan and spray coil cleaner on the evaporator coil inside the ductwork. That may kill some mold, etc in the coil and ducts. The fan motor is under the dash on the far right side of the car. Unplug the wires, remove 3 screws, and it drops out leaving a big hole you can somewhat see the evaporator through. Complete disassembly of the system for a total cleaning requires removing the dashboard and recovering the refrigerant.