I've recently had a stinky mildew smell in my 98 4x4 Blazer. Thought it was from rain that got in when I left windows full open during a deluge a few weeks ago.

After seats dried, a week later I got the smell. Did not feel anything wet. Sprayed Lysol and Febreze. Still stink. Reached under the rugs by door jambs and on firewall. Bone dry. Finally pulled back carpet to floor from passenger firewall. Padding at the floor is soaked, but upper firewall area not soaked. And padding stinks of mildew something fierce.

The fact that the carpets are rubber-backed really keeps you from finding or feeling the water on the carpet surface that is trapped underneath.

Also, I have never had the sweet pungent smell of antifreeze.

And ever since I pulled back the rug from firewall down to wet padding and it dried out, I do not see any drips or wet areas.

If it is a heater core leak, what EXACT path would the water take? Can the leak be more in the middle of the firewall and travel under the center console and THEN drip downward under the carpet from under the passenger seat area?

I am stumped - and I really do not want to take apart the dash board if it is NOT the heater core.

It also occurs to me that there could be an intermittent heater core leak.

 

It also just occurred to me .... could this be from a rear or front windshield washer fluid leak?

Where does the rear wiper fluid hose get routed?

 

NOBODY knows where the windshield washer rear lines are routed?

 

Are you sure it's coming from the carpeting? It's a common symptom of mold buildup on your evaporator and in the HVAC ducts. It's common during the Summer, because a lot of people shut their vehicles off while the AC is still on... this creates a great environment for mold. They make aerosol products to kill it off... you'll crank the vehicle, run the AC (but NOT on Max AC - you want fresh air being drawn in), spray it into the ducts under the windshield wipers, let it run for five minutes.. repeat as needed. You'll also spray into the dash vent next to the passenger door (and you'll want a heavy foaming cleaner for this).

 

if the evaporator drain is clogged it will breed mold and smell pretty bad. The windshield washers are on the hood, the ducting is all under the hood and doesn't even touch the firewall. I'm not sure however where the rear is routed, but if you use washer fluid if usually wont mold and has a chemical or scented smell

 

It's not the carpeting itself. As I said it is the padding UNDER the carpeting, on the front passenger side. Padding was soaked, you could wring it out.

I at first did all that spraying of Lysol/Fabreze into the air ducts. That did not help. The nasty smell was the soaked padding under the carpet.

Just had a LOT of rain here. Did not run the Blazer since Thurs. Left the carpet pulled back so the padding could dry BEFORE it rained. Padding did dry out. Now need to see if the padding is wet again from rain getting in somewhere.

 

Front passenger side? Condensation building up on the evaporator is a common culprit here.

 

How does the water condensation get into the passenger area? Is there something that is clogged, that should be draining?

 

UPDATE: Here it is a month later. Still have NOT found the source of all the water. Padding has been bone dry all this time. A slight mildew smell.

A few weeks ago I used a Snap-On cooling system pressure tester. Pumped up the system at the radiator neck to 17 psi. System held pressure for 30 minutes. No leaks, hisses or drips.

Either the heater core self-healed, or the water came from the evaporator not draining properly.

 

Do you or anybody with you smoke? Did a previous owner smoke? The smoke particles settle in the duct work and will grow mold and mildew. Lysol into the air vents at the base of the windshield will stop it, for a while.