Hello all, I've been reading a lot about heater cores in recent days since I am experiencing issues that seem to point to an AC/heater problem. I want to post my findings here first before tackling an all day task if it is unnecessary.

1. I smell antifreeze coming from the vents when my AC is on. This began 3 days ago.

2. I do not see a mist or fog inside of the cab.

3. The floorboard is dry, both the driver and passenger side. I have not felt under the carpet, but the carpet, under the mat, is dry.

4. I have not noticed any antifreeze in my driveway or in other places where I have parked.

5. The antifreeze level is still in the acceptable range.

6. The smell is more prominent when on max AC. When on normal AC or on Panel the smell is not as noticeable. When I turn the heat on, the smell is not as noticeable as it is on max AC.

7. The heat and AC both work fine, but to be honest, I have not run the heat full blast for more than a minute yet to see if I notice a fog.

Any ideas on what I can check to narrow down the exact problem?

If it turns out to be the heater core, I've found most/all of the tutorials and pictorials on here for replacing the heater core and feel comfortable in doing that if necessary. If it needs replaced, what are the blend doors? Do they come with a new heater core? How will I know if those need replaced? Would it be worth my time and money to just purchase those and replace with the heater core while I have the dash out?

The vehicle is a 2002 F150, 5.4L, 4x4 with 120,000 miles.

Thanks for any ideas and suggestions.

 

Been there, done that.

Sounds like the first stages of the problem and very similar to what I experienced with my 97 F150. One thing for sure, it will gradually get worse. Usually you will not see leakage in the cab and you are probably not seeing any liquid under the truck due to the leak not being large at this point, just a vapor leak. In time you'll see fluid drain down the front passanger side of your engine fire wall. If you're wiser than me, you'll plan a weekend in the near future before it gets cold to remedy the situation. The step by step instructions you mentioned are excellent. I wish you well my friend and hope it all works out for you.

p.s. To isolate the problem, what I did was bypass the heater core by attaching the 2 heater lines together. If you no longer smell the "smell" then you know...

 

Sorry to tell ya....but it is probably the heater core... not very fun to change out. But it could be leaking at the hose fittings. But i would try bypassing it like he said.

 

Thanks for the input. I was afraid that it would be the heater core. I'm not really opposed to wasting an entire day doing it, but before I get wasted on a case of beer, take a day (or two) off of work, and replace the heater core I figured I would post here in case if there could some way be a minor issue elsewhere that needed addressed. For those that have done it, please let me know if there are any parts that I should get in addition to the heater core. From what I can tell from the posts here is that I should get the core and replacement o-rings/clips at a minimum. Also there is a special tool required to remove the hoses, but I can get by without that by cutting the posts off of the old core for removal. I'm also going to get new radiator hoses and a t-stat while I'm at it since the truck has 120,000+ miles on it and those have never been changed. Is there anything else? I'm going to get to the shop today and pick up parts and try to tackle this tomorrow.

Thanks.