smoke / vapor coming out of the vents

[hgallegos915]

Ok , I think I had a bad heater core.


So heres the deal. I can drive the car around and doesnt overheat or anything. I noticed the last 2 days that small traces of white smoke / vapor comes out. Its getting worse and worse. At one point I tought the car was on fire but It does not smell like smoke. Its really light and you can barely see it. It also today started to come out of the hood. I assume the heater hoses are bad but I just replaced them last season.

Do you guys feel its the heater core? It even happens if I have it set to cold.

I assume its been happening for a while as there is green sticky grime that fell on the ecu(which i cleaned) that came out of the vent thats on top of the ecu.

What the hell is going on.... am I better off cancelling out the heater hoses until I replace the core? could it be bad heater controls?

[Evo_Spec]

sounds like a heater core to me

[Daninski]

Select your heater off and if it stops after a couple of minutes you've answered your question. Good Luck

[Ryan]

Or loop it out from the engine bay and see if it stops

turning the heater core off, if I'm not mistaken, in these vehicles, just takes the air from a different path, there isn't actually a valve switching the coolant flow. Maybe I'm crazy... its been happening a lot lately.

[hgallegos915]

Anyone that has the shop manual, can you tell me how to remove it?


its amazing that i can do a klze swap and turbo the hell out of my car and I cant replace the heater core.


From what my previous knowledge tells me, you have to remove the dash in order to get to the heater core? or can i get away with getting it from the bottom...

since mazda made this car, im sure they made it impossible to remove or at least hard.

[hgallegos915]

WOW I just read the online shop manual... and it looks like a sucky job... I may end up just by passing the hoses and dealing with the cold. At least it doesnt get under 35 here .... better bundle up if I want to be driving my mx3... I do not feel like removing the dash to get that crap out. Ill probably remove the dash in the summer and replace it anyways.


So this sucks, my mitsubushi eclipse, heater only works at full blast and now my mx3's heater is dead... sweeeet....

[Daninski]

Just go out and buy some 'liquid' radiator stop leak not those stupid pellets. You probably feel the same as most of us, if it doesn't improve horse power or isn't a sound system upgrade we're not interested in doing it.

[wytbishop]

I came accross an MX-3 int he junk yard a couple of years ago with the dash out and was looking at the HVAC console and yes...there is no way to remove the heater core without removing the dash. I couldn't believe it when I saw it.

Worst engineering design ever.

[Savin]

Wyt, A lot of cars are like that though. My cousin's '87 Camaro is like that (although you can just pull the dash forward a bit), same with my Mustang and Thunderbird, you have to remove the dash.

Anyway,taking the dash isn't a hard or sucky job, it just takes a little time finding all the screws. You should be able to change out the heater core in about a day taking your time.

[Daninski]

There is a post here showing how to remove a dash with pics of all the screw locations but I have no time to search it right now sorry.