HVAC AC Smell on 4th Gens?

Hey all, I have a 2019 Expedition Limited and I have had some issues with the HVAC smelling musty right after when the truck had AC on. I've tried the disinfectant method on to the HVAC intake through the cowl but it comes back eventually.

Upon further review, it looks like F-150s and super duties also have the same issue to due to poor design on the AC Drain through the firewall. The fix is a rubber elbow (looks like a PCV valve elbow) as seen in this video


I have ordered the "Ford part" as noted through Amazon for $18 and I am currently waiting for it to try out if this is the right fix. I am just curious if others out there in the Expy/Navigator world have had the same issues.

What it usually comes down to is mildew building up in the HVAC making that smell. A way to prevent it is to turn off AC about a minute from your final stop, and just run regular air. This will stop the mildre that builds up in the compressor and HVAC area. It might be too late for you if it is really bad. Hopfilly that part will fix it for you.

2020FordRaptor said:

What it usually comes down to is mildew building up in the HVAC making that smell. A way to prevent it is to turn off AC about a minute from your final stop, and just run regular air. This will stop the mildre that builds up in the compressor and HVAC area. It might be too late for you if it is really bad. Hopfilly that part will fix it for you.

Click to expand...

Thanks. It is definitely mildew due to the water sitting in the system and not draining. The issues doesnt really present itself until late spring/summer time when AC is most in use. I have a steep driveway of 12-13% decline when going into the garage and I have been letting it sit for 2-3 minutes right after getting home on the steepest part of the driveway. In doing so, it eliminates the inherent water tension that causes the problem.

Once I have the elbow part, I'll also replace the cabin air filter and try to wipe most of the HVAC ducting with disinfectant

RABAYL01 said:

Hey all, I have a 2019 Expedition Limited and I have had some issues with the HVAC smelling musty right after when the truck had AC on. I've tried the disinfectant method on to the HVAC intake through the cowl but it comes back eventually.

Upon further review, it looks like F-150s and super duties also have the same issue to due to poor design on the AC Drain through the firewall. The fix is a rubber elbow (looks like a PCV valve elbow) as seen in this video

2019 F-150 Wet Floor Repair

www.youtube.com

I have ordered the "Ford part" as noted through Amazon for $18 and I am currently waiting for it to try out if this is the right fix. I am just curious if others out there in the Expy/Navigator world have had the same issues.

Click to expand...

I have that occasionally on my 22 Timberline. I live in AZ and its dry so one would think otherwise but only a few times recently I have smelled it and knew 100% what it was. My old BMW was notorious for gathering mildew even in AZ and I would have to flush it with cleaner monthly.
Did not like the fact I was smelling it in the New Expy after 7 months. So far its only been a few times so time will tell.

Just checked my carpet on passenger side: it's wet (not soaked, but wet). No smell, however, but can imagine that it will mildew after a while. Ordered an elbow to do the above fix.

RABAYL01 said:

Thanks. It is definitely mildew due to the water sitting in the system and not draining. The issues doesnt really present itself until late spring/summer time when AC is most in use. I have a steep driveway of 12-13% decline when going into the garage and I have been letting it sit for 2-3 minutes right after getting home on the steepest part of the driveway. In doing so, it eliminates the inherent water tension that causes the problem.

Once I have the elbow part, I'll also replace the cabin air filter and try to wipe most of the HVAC ducting with disinfectant

Click to expand...

That could be your problem too. On Raptors I know a common thing to replace is the Cabin Air Filter as it can start to smell.

I had this issue with my 19 F150 and the dealer said they couldn’t find anything wrong. Issue was never resolved, I would just spray Lysol in the fresh air ports every other week to help keep the odor down. Dealer replaced cabin filter on two separate occasions and they said they could figure out the issue.

I checked my 2019 XLT to see if mine was missing the 90° nipple coming off the the drain for the A/C against the firewall. Mine was not installed during the build date of 11/19. Surely creating in my opinion that condensating water in being forced not to drain properly and settling in the plenum creating 2 issues. Water being drained into the RS of vehicle and also creating a foul smell when the A/C is used. It seems to me that the drain without that directional 90° the hot air from the engine is being forced back into that small opening affecting the water into the cab along with the water not draining properly creating that foul smell when first the air is used. I have inquired about the TSB through my ford dealership to see if they would cover this part. I have 40k on mine and this fix would fall under the TSB Guide for repair procedure. I have the smell when I turn on the air but fortunately haven't had any water leaking into the cabin and wetting under the carpet. I will have this done either by ford buying it or paying for it on my own. Just my take on this matter.

Have you changed out the interior cabin pollen filter? It is located behind the glove box. Motorcraft FP-92 is the part number. There are a few helpful YouTube videos that detail the procedure.