steam/light smoke coming through the vents

gearshift · 08-05-04, 12:14 AM

I started my C4 Vette up this morning and smelled a bit of anti-freeze smell. Then I turned on the AC and then the heater and steam/smoke started coming out the vents. The temp gauge read 198 and the car ran fine. I turned off all of the heating and AC and I could not see any steam/smoke coming through the vents, but my window fogged up, so something invisible was still coming through.

I have had the fans and water pumps replaced. Fluid levels look fine. Any thoughts on this one?

Thank you in advance.

**paintdaddy** · 08-05-04, 12:17 AM

sounds like its time for a heater core

**Ken** · 08-05-04, 12:44 AM

steam/light smoke coming through the vents

I'm sorry, but when I first saw that I thought - steam, light, and smoke coming through the vents! My initial reaction was that it sounded like a bad Hollywood movie about the devil or something.

If there's no indication of dampness around the carpeting in the heater core area, and all of the fluid levels appear to be normal, it may simply be a matter of high humidity in the cabin for a while until the heater/ac dried the air. Any amount of moisture contained in a closed cabin will sometimes show itself as you described.

I apologize once more for the wise crack above, and hope someone can help you with your question.

**vee93** · 08-05-04, 12:56 AM

Check your lines for leaks. I just had a pressure regulator replaced and although I didn't have smoke--the anti-freeze smell WAS coming through the vents. My A/C is working again. The p.r. looks like a small version of an in-dash cig lighter. From what I can make out, the numbers on it read: 22536359/3159C. Hopes this helps.

**Ken** · 08-05-04, 01:07 AM

Now that I think about it, my truck has that aroma every now and then and it always cause me concern, but I can never locate the source; the odor is gone by the time I am stopped.

gearshift · 08-05-04, 10:20 AM

Thanks for some of the feedback. The key here is not the smell, but the smoke/steam that now is pumping out like a banchi every time I turn on the AC or heater. Also, there is a constant release of smoke that fogs up the mirror, but you can't see it.

Does anyone know of a good place to order a heater core online? Also, any write-ups on replacing. I did a search and I know it is a pain staking process to remove, but the Haynes was pretty light in content and no visuals.

Thanks

vettepilot · 08-05-04, 10:42 AM

Originally Posted by gearshift

Thanks for some of the feedback. The key here is not the smell, but the smoke/steam that now is pumping out like a banchi every time I turn on the AC or heater. Also, there is a constant release of smoke that fogs up the mirror, but you can't see it.

Does anyone know of a good place to order a heater core online? Also, any write-ups on replacing. I did a search and I know it is a pain staking process to remove, but the Haynes was pretty light in content and no visuals.

Thanks

How long a period of time did you allow the A/C to run? If it was just for a few seconds it probably did not clear all the moisture from the ductwork and / or plenum chamber in the HVAC mixing chamber. Let it run for at least 2 minutes and see what happens. If it still continues to blow moisture / fog/ smoke, then you have lots of water and or coolant in the heater core box area. That can come from water seeping in from outside, or the dreaded leaking heater core. Either way, you need to find the source in order to fix the problem.

vettepilot

**The Car Whisperer** · 08-05-04, 05:32 PM

Check the clamps on the inlet and outlet hoses right at the heater core in the engine compartment, it's a slight posibility that they are leaking and the anti-freeze could be leaking into the heater box through the firewall seals there. It's not likely though, sounds like a small leak has developed in your heater core. Especially if there's a distinct anti freeze smell inside the passenger compartment and the windows are also fogging up.
You could disconect the heater core from the system and pressurize it with air to see if it holds pressure, it should hold the pressure indefinitely if it's good. If there is a leak you should hear it hissing inside the car. The only way anti freeze can get into the heater box is if there is a leak in the heater core or if the hoses just outside the heater box on the engine compartment are leaking under pressure and bleeding through the seal where they enter the heater box. I don't know of or see any other way for antifreeze to get in there. If the core is leaking you can temporarily by pass it by installing a U shaped piece of heater hose at the end of the heater pipe in the engine compartment for now.

gearshift · 08-05-04, 06:54 PM

Great feedback. I am going to tackle this tonight and start learning if the heater core is leaking. I like the bypass option as well for now. It is still summer!

Thank you

vettepilot · 08-05-04, 07:11 PM

Originally Posted by gearshift

Great feedback. I am going to tackle this tonight and start learning if the heater core is leaking. I like the bypass option as well for now. It is still summer!

Thank you

Be carefull about the by-pass option, the heater core does perform the duty of supplementing the radiator in the complete cooling system. If you begin experiencing higher than normal coolant temps after by-passing, then your only option might be to tackle the job now, even if it is summer. Additionally, if you have the automatic climate control system, the outlet temps are controlled by use of both the A/C evaporator for cold air, and the heater core to maintain the correct vent outlet temps to maintain a constant temp.
Most people don't realize the capacity that the heater core has to help reduce coolant temperatures.

vettepilot

gearshift · 08-06-04, 10:23 AM

Yes, I have climate control, which is does really work (half the buttons do not function and I get a plethora of codes and lights when I turn it on) probably due to the bad heater core. Looks like I am going to tackle the project.

If anyone has details on replacing a heater core, I would appreciate that. I will also share the details when I am done.

Cheers

**The Car Whisperer** · 08-07-04, 08:28 PM

I realy don't see how the bypass option can possibly cause an overheat problem. When the AC is on water circulation in the heater core is stopped because the heater valve closes off the heater core from any coolant circulation. It is still presurized within the system though so you could still have a leak unless you where to completely isolate it from the system.

**WhalePirot** · 08-07-04, 11:49 PM

Originally Posted by gearshift

Does anyone know of a good place to order a heater core online?

Probably cheaper to get yours redone. I just heard that GM is having an electrolysis problem; heater cores are being eaten up. My friend is going on #3 with his Suburban. Y'all seeing this on the later C-4s?

**WhalePirot** · 08-07-04, 11:53 PM

Originally Posted by The Car Whisperer

the heater valve closes off the heater core from any coolant circulation.

Actually, I don't think it totally closes. I read, some years ago, that bypassing it was another way to get the A/C colder, as that valve was not closing fully. It has always been a good preventive maintenance idea to run the A/C once a week or so, to keep the seals lubed and the heater to flow fresh coolant through it.

I am not saying that the heater is an integral part of the cooling system, but certainly it can serve as 1) additional cooling, in unusual situations, and 2) helping to determine if a given car needs more radiating surface.