When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
An update on this, with a twist. It seems that it is not the exhaust leaking fumes, but rather the A/C that is releasing the CO2. (BTW, it's not monoxide, as I mistakenly wrote above. The device measures carbon dioxide.)
The recirculating has a faster and higher concentration, but also the outside air brings in the CO2 - but not when the A/C is switched off.
Why would the A/C blow out gases that make you sleepy?
The vehicle is in great shape, BTW, looks and drives like new. Except for the dash...
R134a is pretty harmless. You would have to be exposed to near industrial amounts to be concerned. Or the AC would have to release all at once to even have a slight chance of causing harm. Even then it would not make you sleepy. There is no CO2 in the refrigerant system.
R134a is pretty harmless. You would have to be exposed to near industrial amounts to be concerned. Or the AC would have to release all at once to even have a slight chance of causing harm. Even then it would not make you sleepy. There is no CO2 in the refrigerant system.
Thanks, that's pretty much what I've found out so far. It's a mystery. Any ideas what it could be?
LOOOOL No, mate, relying on the device. Cross-tested in my other 2 cars and it seems reliable. It measures CO2 in parts-per-million (ppm) and stays in the 400-600 range when the A/C is off, then as soon as A/C is switched on in recirculate mode, it just starts climbing... at 1,000 ppm the alarm sounds, and it keeps climbing to around 2,500 ppm, within a 3-mile distance driving - so it's fast. A few moments after I click off the A/C, it starts dropping, continuously back to 400-600 ppm. Baseline in fresh air outside is around 400 ppm.
I agree it's not the A/C gas, unless perhaps PO didn't use R134A.
I've also checked the exhaust very carefully, found a little bit of tightening I could do on one bolt at the downpipe from manifold, but otherwise I'm pretty sure there's no leaks. And the recirculate vs outside air also seems to work correctly. I sprayed some perfume outside, and none came in on recirculate, but the moment I clicked outside air, the scent entered the cab.
Next step I'm thinking to just have the A/C gas replaced. Other than that, perhaps there has been some weird repair in the A/C system components? Maybe flushing with weird chemicals? But how long would they last and what would expel CO2 continuously?
I'll update after new R134A goes in - in the meantime, any ideas much welcome.
Did you try to tighten the manifolds? Its a bit more work and you have to do it properly so you dont crack em. Meaning tightening all the ones you find a little each, sorta like when do valve cover gaskets. While its possible that something weird was added to the AC system, I can think of nothing besides propane that would emit CO2, even then it needs to burn. And you would smell the propane.
Maybe get someone who has not driven it to hope in and see if they smell exhaust fumes. You may be desensitized, assuming it is exhaust.
Last edited by DakotaTravler; Jan 11, 2020 at 09:51 AM.
If op had an exhaust leak big enough to quickly set off detector, then it would probably cause a driveability issue or at least a check engine light. Since its only when the ac is on, it could be a leaking evaporator with incorrect refrigerant. ...ie propane. It sounds like a long shot, but given the circumstances of this being such a weird problem, I would recommend evacuating refrigerant out completely and re-checking with carbon dioxide detector.
