Sweet smell coming from AC

[Jaiguru]

For the past couple of weeks I've been getting a "sweet" smell in the car but only when the AC is on. Any idea what this could be and if it's a quick diy fix before I take it to get looked at?

 

[LTC8K6]

Coolant can smell sweet.

Heater core leak?

Check your engine coolant level.

 

[Raizinman]

Coolant can smell sweet.

Heater core leak?

Check your engine coolant level.

Anti Freeze is sweet smelling - very likely leak in the heater core.

 

[KingstonU]

I've had this happen as well. Heater core. I had to drive with that smell for months, not sure how toxic it is.

 

[Oric]

Low level toxic in breathed form, worse than (x3) cigarette smoke if you want a comparision

 

[Jaiguru]

Is there anything specific I can look for to see if it's the heater core? Also, if it is the heater core will it most likely need to be replaced or can it be patched somehow? I'd really like to be able to fix this myself but I'm pretty sure my very small amount of car repair experience is going to make me take it to a specialist.

 

[exdeath]

Check the condensation drain port\tube on the passenger side lower firewall and see if it's dripping green stuff.

Or just look for spots on the ground in that area that are slimey and don't evaporate; that's antifreeze.

Most common cause is the barb where the heater hoses connect in the engine bay crack at the end tanks. It's either going to be plastic or cheap cast powdered aluminum and not readily repairable. Even if you can repair it, you're still looking at pulling the dash apart to pull the HVAC box out to get to the heater core, and this could involve discharging the AC system (the evaporator core is in the same box) and draining coolant.

If you are lucky, the manufacturer provides an access panel in the HVAC box to pull the heater core/evaporator/blower motor, etc out from under the passenger dash or behind the glove box. If you are unlucky, you need to remove the entire dash and remove the HVAC box as a whole unit first.

Quick fix if you don't need heat is to pull both heater hoses from the firewall and bypass the heater core: join the hoses with a small section of pipe and two hose clamps.

 

[lokiju]

It's going to be a coolant leak IMO.

Buy some coolant dye like this stuff and then you can use a blacklight to find out easily if and where the leak is.

If it's a hose leak, that's easy enough to fix on your own.

I've replaced a few radiators over the years on my own and it's really not rocket science. Can save you a ton of money vs bringing to someone.

 

[exdeath]

It's going to be a coolant leak IMO.

Buy some coolant dye like this stuff and then you can use a blacklight to find out easily if and where the leak is.

If it's a hose leak, that's easy enough to fix on your own.

I've replaced a few radiators over the years on my own and it's really not rocket science. Can save you a ton of money vs bringing to someone.

Interior coolant leak is always going to be heater core. Don't even need to leak test. There is no other coolant path to the interior. The HVAC box and hose barbs also seal against the firewall with compressed neoprene gaskets normally. If there is coolant smell in the AC, it's coming from the heater core and leaking inside the HVAC box. The only evidence besides smell is going to be coolant dripping from the drain port, possibly steaming/fogging of the bottom of the passenger side windshield as the hot coolant steam works it's way up the defrost vents.

And replacing a heater core is nowhere near as easy as a radiator, it's a big pain in the ass on most new cars.

 

[desy]

yeah changed a core once quit a job

 

[Raizinman]

The poor mans fix is a $3 can of radiator stop leak.

 

[Bacstar]

And replacing a heater core is nowhere near as easy as a radiator, it's a big pain in the ass on most new cars.

Happened on my old car which was covered under warranty. Replaced the heater core. Dealership kept it a couple days because they totally had to rip apart the dash/center console to get to it, and when I saw the paperwork, the repair would have costed $1200.

 

[SparkyJJO]

The poor mans fix is a $3 can of radiator stop leak.

I would never put that crap in any car I cared about.

 

[Jaiguru]

Ok, so I'm on my lunch break at work and I've had the ac running full blast for about 10 minutes now. I can't smell anything coming from the vents now but there is a strong smell when I pop the hood. It smells exactly like maple syrup.

I checked the coolant level and its completely full and there are no noticeable pools of coolant on the ground. Only water but I know that's normal. I really appreciate the input so far. The more I know about what the problem might be the sooner I can get this fixed.

 

[leper84]

The poor mans fix is a $3 can of radiator stop leak.

Don't set someone up for failure...

 

[manimal]

To be fair he did say poor man not smart or capable.

I do agree that that crap should never be anywhere near your car.


Hell the used car market now is full of landmines from guys who blow head gaskets and put in that Blue Devil crap and dump the car. I have seen 3 cars like this this year.

 

[5150MyU]

Maple syrup=You have a coolant leak-Heater core generaly slimes up your windshield.
Under hood leak(waterpump) just tends to stink.

 

[BUTCH1]

Check the condensation drain port\tube on the passenger side lower firewall and see if it's dripping green stuff.

Or just look for spots on the ground in that area that are slimey and don't evaporate; that's antifreeze.

Most common cause is the barb where the heater hoses connect in the engine bay crack at the end tanks. It's either going to be plastic or cheap cast powdered aluminum and not readily repairable. Even if you can repair it, you're still looking at pulling the dash apart to pull the HVAC box out to get to the heater core, and this could involve discharging the AC system (the evaporator core is in the same box) and draining coolant.

If you are lucky, the manufacturer provides an access panel in the HVAC box to pull the heater core/evaporator/blower motor, etc out from under the passenger dash or behind the glove box. If you are unlucky, you need to remove the entire dash and remove the HVAC box as a whole unit first.

Quick fix if you don't need heat is to pull both heater hoses from the firewall and bypass the heater core: join the hoses with a small section of pipe and two hose clamps.

They sell a bypass kit with a section of pipe and clamps for about $10, I used one once before eventually replacing the core, OMG it's a long, frustrating experience, I had to drop the steering column, remove the center console, ect. I spread the job over 2 days, it was that bad...