I'm having AC problem when towing. Truck is a 2015 F250 XL. I bought it used at 82k miles in June. Had pre inspection done and AC worked great they said (which it has been). I changed all fluids when I bought it. I have about 87k miles on it now. Its my daily driver and I use it to tow our trailer (7-8k lbs) occasionally. I've towed with it through the summer and never noticed a problem until last week. I was towing the trailer and the AC blower was weak and the air was not as hot. When I came to a light it sped back up. Air flow decline was noticeable but not uncomfortable. Fast forward to today, and I just towed the trailer about 3 and a half hours. We stopped for lunch for about 15 mins and truck stayed on. The longer we towed the worse the ac became. The blower was weak even on full blast and the air was semi cold. When we got to our destination and were checking in the blower started to have more air flow. We unhooked and I had truck off for about 30 mins. When I went to move the truck again, it had a little lag as I turned it on. All fluid gauges were showing good. I don't know the engine temp because I have an XL trim with a cheap radio (will upgrade to a radio that gives out truck data soon). Any thoughts on what it might? I use the tow/haul function if that matters. We will be driving home Monday, so hopefully we make it without the wife getting too upset ....

Common problem with the 6.0, clutch is slipping. You can usually remove a shim to bring the gap back under .030" where it should be (between .015-.030"). Sometimes it can be a vacuum leak, if it was a vacuum leak the air is re-routed to defrost.

Thanks. I found a good youtube video that walks you through repair. Looks easy. I'll do it this upcoming week. We'll just tough out our return trip home.

Ok, I'm leaning toward possible vacuum leak. Dewrecking crew mentioned the air would reroute to the defrost and that might be happening. When the air flow decreases, the air still sounds like it is coming out full blast. I wonder if it's coming out of the defrost and that's why I hear it. I never thought to check/feel if that is happening. Would a vacuum leak change AC air flow speed when I'm towing vs when I'm parked and idling.

If it is a vacuum leak, would it be safe to tow our trailer home. I haven't noticed a change in towing power but I have noticed a slight decline in mpg (about .5 less). We leave our campsite on Monday.

Another question. Recently when driving with AC on I hear a soft sort of hissing sound. It sort of sounds like a puff of air being expelled. It only happens with AC on. It's not a constant hissing sound but it happens at regular intervals... Would that be further evidence of a vacuum leak? Sorry for all the questions, trying to get a handle on the situation. Been googling the last hour...

Any resolution here Drewbie?

AggieRob93 said:

---

Any resolution here Drewbie?

---

Nothing new. I towed the trailer home Monday morning and had similar experience. We left early before it got too hot. AC started out good but slowly got weaker and warmer. It really became noticeable after about 1.5 hours of driving. We stopped after about 2 hours of driving to refuel and grab some roadtrip snacks. Entire stop was about 20 minutes. Truck was mostly off during this time. After refueling, AC was good and blowing well until about an hour later when it slowly started getting weaker and warmer. We made it home before truck got too hot. Gauges were all reading good and no noticeable loss in engine power. Gas mileage seemed par for the course. My tires were aired up slightly higher than typical, so that may have accounted for the about .5 mpg loss in gas mileage.

I had a very busy week so haven't had time to look at the truck. I've only used truck for short trips so haven't noticed AC issues. I'm hoping to check out the AC clutch later this week. I did a real quick hose check, and none of the easily accessible hoses felt brittle or loose. Hopefully I'll have a better idea or resolution by this weekend.

I had a similar problem with the coil freezing. Run the blower without a/c for several minutes to defrost. Returns to normal for the next 45 or so minutes.

This a 6.7 or 6.2?

Hville Havoc said:

---

I had a similar problem with the coil freezing. Run the blower without a/c for several minutes to defrost. Returns to normal for the next 45 or so minutes.

---

Did you change the temperature? I played with it a little last time and nothing helped. For example, I turned off "max" but it didn't help. I only kept it there for about 1-2 minutes, though. I'll have to try it longer next time.

1agswitchin4lanes said:

---

This a 6.7 or 6.2?

---

6.2

Finally got under the truck this afternoon. The AC clutch gap was likely around .008 to .01. It was definitely smaller than .012. I tried .012 and it wouldn't fit *insert GB joke*. Would too small of a gap be the cause of my problem? Given the location, I can probably reach it and add a spacer if needed.

The AC has gotten a little worse over the last week. The flow is fine but the air is warmer. Almost to the point of paying someone to fix it if clutch isn't problem. I'm fairly handy with directions and videos but not knowledge enough to go in blind and try to troubleshoot.

I also noticed a little light brown fluid when under truck
I'm assuming it was oil. It didn't smell like oil, though. I had an oil change last Friday and didn't drive the truck this weekend so assuming it's residual oil that got splashed around. It wasn't enough to form a puddle or anything. I'll just keep an eye on it and make sure I'm not leaking oil.

Have you popped the hood with the truck and a/c running to check a/c clutch engagement?

Like 1ags says, slap some gauges on it. If charge is low, low pressure cutout would cut power to the clutch coil. System can also freeze up with a low refrigerant charge. If refrigerant is low, obviously there would be a concern of a leak, which might also allow trace amounts of oil out, and could also let moisture into the system. Check connections at a/c line crimps, condensor, receiver/dryer, perhaps evaporator if you can get to it and look for some oil residue or build up.

Got some gauges on it and both high and low sides had lower pressure.

With engine off (temperature 74F), high pressure was 75 psi and low pressure was 65 psi.
With engine on (I had just driven it and I let it sit idling for 5 minutes), high pressure was 125 psi and low pressure was 10 psi.

Since both are low, would just adding refrigerant be the best thing here? Would you consider a leak detection kit? Both? If so, is there a specific order to do them in? Also, should I get a refrigerant with a leak sealer or one without? Most Youtube videos use refrigerant with leaker sealer, but I've read a few comments that it's not necessarily good. Thanks for all the help!

Yes.

Buy at least one can of R134a, no dye, no filler, no nothing.

If you're in Houston and dont have the ability to charge, bring it by the house.

1agswitchin4lanes said:

---

Yes.

Buy at least one can of R134a, no dye, no filler, no nothing.

If you're in Houston and dont have the ability to charge, bring it by the house.

---

Thanks for the offer. I'm in SA, though. I've spent a good hour watching Youtube videos, so feel like I have a decent handle on it. Do you recommend just adding/topping off the R134a? Or vacuuming out the entire system and recharging it that way?

No, I would add one 12 oz can. Brand is irrelevant. buy the cheapest one you can.

Add one can and see if you can get the low side up. With 90F ambient temps, low side should sit around 40-50 ish depending on humidity, and the high side should be over 230-250.If your llow and high side is still low you can add another can.

Hopefully this gets you were you need.

If it leaks out again in a few weeks, you need to start looking.

My mercedes needs refilling every 3-4 mos. I dont bother looking for the leak.

I got my AC to work, but it's not fully charged yet. I bought 2-12 oz cans of refrigerant and started hooking up the yellow hose. I had trouble creating a vacuum with the yellow hose. I kept bleeding it and playing w/ the nozzle to find out why. I eventually found out that the yellow hose did not have an O ring. So I went to O-Reiley's and got another loaner that had all the pieces. I came home and put in the refrigerant and it get the AC cold. This afternoon the air coming out was in the 90s. After the refrigerant it was high 40s.

However, even with the 2 cans I could only get my charge between 25-30 psi and 175 psi. This was after using 2 full cans. In reality, I probably ended up only putting about 1.5 cans after bleeding and figuring out the yellow hose was leaking. Prior to starting, I was around 5-10 psi, so it came up about 20-25 psi. Would 18-20 oz of refrigerant only bring it up 20-25 psi. I looked on the sticker and my truck says it is 29 oz charged.

In my head the numbers seem somewhat right. If I was between 5-10 psi, I was probably really low. Maybe around 3-4 oz of refrigerant (based on percentages). If I put in about 18-20 oz, that means I have around 21-24 oz in there. That is a little over 2/3 fully charged. So 2/3 of 45 puts me around 30 psi. Which is around where I was at. I will say that when I got to about 25-30 psi, the needle moved VERY slowly as I was adding in more refrigerant. That may have been when the cans starting getting low, though.

Does that seem about right given my situation, or did I mess something up. I was really careful to bleed the yellow hose and make sure I saw refrigerant coming out so I did not put air in. Maybe I let out a little more refrigerant than I thought? There was one time where I thought the blue valve was closed but it was open. The refrigerant can was already attached though, so I don't think I introduced any air...

I'll probably put another can in tomorrow afternoon unless ya'll tell me I probably messed something up based on my description. If that happens, it's off to a professional.

If you haven't been buying the refrigerant with oil added, you need to on the last can

DeWrecking Crew said:

---

If you haven't been buying the refrigerant with oil added, you need to on the last can

---

I'll do that next can. I didn't add oil this time because I read only do that if you are replacing parts. But it makes sense that oil has been lost too since my system was so low. Do you think the oil in one can would do? Or should I add a little extra to the yellow hose before adding the refrigerant?

High 40s is about in range with 90 outside.

I'd be hesitant to add a whole 3rd can. Or at least all of it.

This is the problem with doing this at home. But we all do it.

Add half the can and see if it gets you where you need.

The new style cabs are self sealing so you should be able to just remove the line and it will hold for next time.

Did you have the low side valve open while the yellow hose was leaking?

txyaloo said:

---

Did you have the low side valve open while the yellow hose was leaking?

---

No. I made sure not to open the low side until I had a vacuumed yellow line and could purge out refrigerant where I saw it. I only opened the blue after I got the new manifold.

There was a time where I had the blue valve open when I thought it was closed but this was after I had the yellow vacuumed and was opening/closing the refrigerant valve to see if it was done. Since it was vacuumed I assume no outside air got in..

Well something else might be wrong with the AC. I bought another 12 oz can, hooked up manifold, and tried adding refrigerant. I ended up using 1/2 to 3/4 of the bottle. My low side started around 30 psi and finished around 32 psi. The high side finished around 225 psi. Either the hoses had a leak and put very little into the system or something else is wrong. I do not think the manifold leaked. It took forever for the can to empty, and the can wasn't even that cold as it emptied...This is what happened last night when I got around 25-30 psi.

I checked the pressure with a different set of gauges and got a similar reading, so it was not the gauges. AC is still running cold. When I was checking the compressor and hoses, I noticed a piece that I have no idea what it is. I've attached pictures. Any idea what it is? It was near where the passenger fog light would be.

The system won't take any refrigerant unless the compressor is running/engaged.

I don't know what that part is but it looks like it has been there for a good while

That looks like the nose plate of an AC compressor clutch.

Either its yours or someone elses that flew off and into your grille/bumper area.

Post pics of your Kompressor.

Here are pictures.

It was on the inside of my undercarriage in a spot where it would have been hard for it to fly from someone else's car. Maybe this truck had the compressor or AC clutch replaced and this is from the old one?

Not from your compressor. Likely kicked up off the road, and landed where you found it.

Not yours but that splatter is interesting...maybe the compressor blew out before you bought it?

Update:

AC was working well until a few weeks ago. It started blowing out warm air again. I assumed it was because of a slow leak that needed a refill every 8-12 months. So I added some freon.

Pre refrigerant w/ engine on: High 155 psi, Low 25 psi, AC vent temp of 77F. Added about 2 cans of refrigerant and ended up with Low 38 psi, High of 240-250 psi, and AC vent temp between 48-52F. Outside temperature was around 82F and 61% humidity. My low was still a little low, but that is what happened last time.

So I thought was all good until today when I noticed warm air again. So I thought my leak was getting bigger. I decided to buy some refrigerant w/ UV dye to help find the leak. When I took off the low side cap, I noticed some yellow/green liquid in the cap. Sort of like the UV dye BUT I had not added any dye yet and I did not add any dye last time. I wonder if that is a leak...

So today I added refrigerant and this is what happened. Pre refrigerant w/ engine on: High 105 psi, Low 23 psi, AC vent temp 97. Added about half a can of the refrigerant. Post refrigerant initially showed Low 50-55 psi, High 125 psi. The gauges fluctuated but eventually ended with Low 40 psi and High 150 psi and AC vent temp of 71.

So, I have no idea what the problem or solution is. I'm going to call my mechanic and have him sort it out, but we have trips planned the next 2 weeks. So, he can't look at it for at least two weeks. We've decided that we will just take two vehicles. I will tow the TT, leave early, and just suck it up. My wife and kids will follow in her car so they are not subjected to sweat shop temps.

Any immediate thoughts or suggestions I can look into while I wait for my mechanic to look at it?

Hopefully you've added refrigerant oil at least one of those times?

Yes. I added one whole can last time and then a little this time. Not sure how much I need to add. Could too little oil be the problem?

What do you mean by whole can? More than 4 oz?