How to tell if truck AC needs more Freon?

[savin yours]

2010 Cummins. We were on our way home from camping this weekend, when about two hours into the trip, my AC wasn’t blowing out of the vents very much(pulling a 36’ 5th wheel). The blower still sounded like it was on high, but not much coming out of the vent, still cold. Next morning, it worked just fine. Last night and this morning, blowing strong, but all warm air. Don’t wanna spend $40 on a can, and not be the problem.


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[6.5 shooter]

You really need gauges to see what’s going on. If it is out of Freon, I would guess that your evaporator developed a leak. We have replaced a lot of them for that.

[savin yours]

You really need gauges to see what’s going on. If it is out of Freon, I would guess that your evaporator developed a leak. We have replaced a lot of them for that.

Another thing I’m afraid of, buying Freon to just leak out. But I guess it would be worth it to figure out it’s a leak.


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[meltingfeather]

It doesn't get out of the system without a leak.

[Gonzo]

I had a Freon leak on mine, had a guy charge it for $20 and lost the cold air in two days. Brought it back and had to replace compressor and the whole kit that goes with it. Took an $800 chunk out of my waller. This was on a F-250

[Smart]

On the first part.....Freon doesn't have anything to do with the amount of air coming out of your vents. Just the temperature. Weird that your blower motor sounded like high but wasn't pushing air. That could be a blend door issue



Now the blowing warm in the second part does involve freon or a door.....but it could also be a switch that doesn't allow your compressor to kick in. It could also be your compressor clutch is worn and not engaging. Does your clutch engage/suck up to the compressor when you turn the AC on and is it spinning? There is a distinct click you hear when the hood is open and the clutch on the face of the compressor will be spinning. It will be sitting idle if it is not sucked up/engaged.

[denimdeerslayer]

Normally when my dodge is low one r135a the passenger side will blow warmer than the driver side. I'd add some and then all would be good. But two years ago I had all the blend doors and motors changed and did the evaporator core too. That made things back to new cold! I didnt replace the blower motor till some spent brass made its way down into it.

[Hoghuntinfool]

It quit blowing because it was froze up, you surely have a leak


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[Goldeneagle]

Sounds like a problem with the blend door and the doors that change to the different vent locations. Could be electrical or some are vacuum controlled.

[brushhunter]

If air is cold but not blowing hard it is probably an in-cab air filter. Just changed mine last week and it made a world of difference.

[Airtech]

First, make sure the system still has its charge by using gauges to check system pressure. If system has a static pressure of #50 or above the compressor should engage when requested by control head. If no compressor engagement start looking for problems on the electrical side. The problem you spoke of is indicative of evaporator freeze up of moisture on the evaporator coil. The air flow will diminish as it freezes over. Once you shut it down, the ice melts and system will work again. Then when starting it the next morning it would work again. The evaporator temperature sensor can fail and shut the compressor down. It is located in the casework just behind the glove box. The sensor is low cost and can be easily replaced. It snaps into the evaporator case. Using a professional type scanner will show the values coming from the sensor when checking the HVAC system for codes and data. If the sensor has not failed, then info from the scanner may well point to other problem areas.

[brushhunter]

Just read 2010 don’t have the in cab air filters. My 2011 did. Sorry hope you get it figured pretty quick too hot to be without a/c.

[Outback]

Sounds like a problem with the blend door and the doors that change to the different vent locations. Could be electrical or some are vacuum controlled.

I believe blend doors point to a vacuum leak. Might have had a vac hose come look under the hood.

[kruppa24]

On the first part.....Freon doesn't have anything to do with the amount of air coming out of your vents. Just the temperature. Weird that your blower motor sounded like high but wasn't pushing air. That could be a blend door issue



Now the blowing warm in the second part does involve freon or a door.....but it could also be a switch that doesn't allow your compressor to kick in. It could also be your compressor clutch is worn and not engaging. Does your clutch engage/suck up to the compressor when you turn the AC on and is it spinning? There is a distinct click you hear when the hood is open and the clutch on the face of the compressor will be spinning. It will be sitting idle if it is not sucked up/engaged.

X2 on this, I had one one time where the blender door broke, keeping air from flowing.

[muzzlebrake]

I believe blend doors point to a vacuum leak. Might have had a vac hose come look under the hood.

Some of these newer truck have electric modulator motors that operate the blend dampers. Research online how to reset the modulators. My truck has 2, one on each side. I have had to do the reset twice in 182000 miles. No big deal. If however the resets don't work you may have to replace the motors. Some are easy and some are very difficult to get to.