I've got a 96 Blazer with a smell when the heater is on. Pressure check suggests its not a heater core leak.

Question

We were told the radiator was flushed before we bought it. Some antifreeze had spilled on the mats and I assumed that was the smell. When it didn't dissipate, a friend who is a mechanic suggested it was a heater core leak but when he did a pressure check could not find one. He suggested we clean the car and engine well, which we did. Now, it does not smell all the time or when the air conditioner is on but that smell comes back strong through the vents if the heater is turned on. Any ideas?

Answer 1

Change the air filter. Somewhere in the blower assembly or under the vents outside the bottom of your windshield, there should be a filter that cleans the air before it comes into the vehicle. Mine had some oil as well as the normal road grime, dust and dirt. Every time I turned on my heater and/or ac I would smell kind of a burnt oil smell, changed the filter and smell was gone.

Answer 2

How would someone changing a radiator spill coolant on the floor mats inside the truck? sounds fishy to me. Sounds like someone changed the heater core and spilled coolant inside the heater box as well as on the floor mats or the mats got coolant on them when the original core leaked---either way there is some residual fluid in the heater duct---when a/c is on, there are blend doors in the ductwork that draw in outside air only and close off air coming through the heater core so you're not cooling hot air and that is why you don't smell it as much with a/c on. If the cooling system doesn't have a leak, then the heater core should not be leaking but the smell is from fluid in the duct unless it's a tiny pinhole leak in the core....my best guess.

Answer 3

A pressure test will not always show a heater core leak. It can be so small the pressure does not drop when tested. It sure sounds like a bad heater core. You will find a "film" on the inside of the windshield, a sweet smell when using the heat and possible some antifreeze on the passenger side floor.

Answer 4

It still could be a heater core. Pressure testing doesnt always find this type of leak. Make sure your heat control is on full heat when testing otherwise the heater control valve will be shut off. Also check the core intake hoses. they could be leaking and cause for smell inside truck

Answer 5

supply youself a minimum of 8 hours. some heater cores are worse than pulling an engine. i could desire chewing my very own arm off to changing a heater middle on a automobile with A/C. Ford calls for you eliminate the entire dashboard so do never pass there. Ford additionally calls for you pull the engine to interchange an oil pan gasket on an F-150. Yikes! good success!

Answer 6

put some stop leak in the cooling system. if the smell stops ,the core is leakimg .replace before winter.

Answer 7

Possible problem is not mechanical. Good chance you have a dead rodent or other small animal inside. Try an animal expert for clarification and or removal.