The heater has a musty smell,I suspect i need to

Dear Helen,
Which filter? You have the air filter, the oil filter, and the cabin filter.
If it is coming out near the air filter or the oil filter, I should suspect a leaking heater or radiator hose.
A pressure tester for the radiator will help you find those leaks.
If it is near the cabin filter, it should be the drain tube for the air conditioner condenser, which is normal to leak when the air conditioning is running.
Try to catch some of the water that is leaking and see which fluid it is.
Air conditioner condensation water is clear, it even looks drinkable.
Anti-freeze/coolant liquid is colored blue, green, red, or yellow, (it depends on the brand) and has a distinct sweet smell and taste. No, I am not recommending you should taste it.
God bless your efforts.

1 filter. You could also try spraying deodorizer into the cabin air system intake near the hood and windshield from the exterior.

What kind of smell? Sweet like coolant or a musty, decomposing like smell? If sweet like antifreeze it could be your heater core if musty/mildewy or decomposing like smell try replacing your cabin air filter.

Most common cause is water sitting in the bottom of the a/c heater box. Make sure the outside drain is open. There are spray products for using on the vents.

The cabin dust & polen air filter location & replacement


The cabin air filter is placed inside the car under right dash panel near windscreen. See pictures below:

Need to change the cabin air filter, when it gets old it will produce an awful musty smell

I'm 99% sure it doesn't have a cabin air filter. I've serviced many Jimmys and similar GM trucks of the same era and never replaced a cabin air filter or seen a reference of one in manuals. What kind of smell are you experiencing? Is it a musty moldy smell or a horrid animal smell?

The drain should go through on the passenger side under the dash....you might need to replace your cabin air filter.

the more you use it the less you should smell it. Sometimes they smell that way after NOT being used for a period of time.

There should be a cabin filter. Call the parts store to see if they stock one for your car in particular.

Cabin filters are located in stream of the outside air flowing in. I know on a '99 Galant, you just had to take out the glove box, loosen two screws, and out she slid.

It'll be right near the blower motor, above the passenger's foot rest, behind the glove box. Simple hand tools will do it.

Be careful when pulling it out, as it may have leaves and acorns or fur all over it. Simply slide in the new filter and you're done.

You'll be surprised at how much better it'll smell, and how much harder your A/C and heat will blow without the constriction of a dirty filter.

Most cars have the cabin filters behind the glove box, but if not there, then they'll have them under the hood, on the firewall, on the passenger side. Usually inside a small black plastic box.

If your car DOESN"T have a cabin filter, then the musty smell is stuff that is sitting in the heat/ AC system. You can try spraying pine sol or Febreeze down the air intake hole for the system. Mind you, this is not the same as the air intake for your cars engine!

The air intake for the cabin filter will be on the passenger side, under the hood, most likely under a plastic cowling of sorts.

Good luck!