What;s Wrong With My RAM Truck????

[mustang071]

Our 2005 Ram 3500 Diesel (5.9) SRW has been a great tow vehicle for our 7-ton 5th wheel trailer. And after 150 thousand miles, three years ago we had to replace a couple of leaky hoses in our air conditioner. No surprise there. Since that repair, the AC blows cold and steady, towing or not. EXCEPT.

During this past year, on our last three return trips to Texas- one from the Great Lakes and two from Colorado- the blower quits working at about 350 miles from home. The AC is constantly cold, but without the fan blowing, we get very uncomfortable and downright HOT in the cab driving home in the Texas heat. In fact, on the last two trips, the blower quit in exactly the same place, a few miles south of Amarillo heading down 287 towards Dallas.

Each time, we’ve managed to get a little action out of the AC fan IF we can keep the RPM high as we travel. But if we stop at a red light and the engine is at idle, we get nothing. Cracking the window seems to help the blower also, but engine speed seems to be the key. Once on our last trip when climbing a hill, the tranny dropped to low and the fan started working perfectly as the RPM climbed to about 3000. But that lasted for about 3 minutes before dropping back into pathetic, weeny mode.

The Dodge House is clueless; they said the system only needed service which was performed prior to our most recent travel, but that had no positive effect on this fan problem. The AC works perfectly around town and all during the trip, except for the very last 350 miles.
Has anyone out there in RV land had this issue? If so, how did you fix it? Help!

[zcookiemonstar]

I have a 03 Ram and my ac freezes up all the time. When I notice the air is not blowing out the vents I turn off the ac just let the fan run and after a few minutes the air will start blowing out the vents again. I read awhile back Dodge put some ac sensor in the wrong spot and the ac does not cycle on off as it should. I thought I read there was a tech service bulletin that said to relocate the sensor but it was a big job required removal of the ac/heat box to get to it.

[CharlesinGA]

bobsallyh wrote:
On my 2003 Ram the evaporator freezes over the air won't pass. High humidity triggers it quickly. If I park the truck for 15 minutes or so with the ac off water gushes out the drain onto the asphalt.

My '03 2500 standard cab does the same thing. Blows extremely cold, especially on the drivers side, and eventually the air flow slows. Turn off the air for a while then it will blow fine again when you turn it back on.

I think the issue with the passenger side vents is some missing seal foam behind the passenger LH vent, It is drawing hot air from under the dash, venturi style. When it gets cold enough inside those vents finally get cold. My '03 has 5 dash vents. My coworkers early '04 has four vents, they eliminated the passenger inboard air vent in the air bag cover panel.

The fan clutch is a viscous fluid clutch with electric controlled valving. If you start up from a stop with the A/C on, the fan will roar very loudly if it is working, up to about 20 mph, at which point the computer sees forward speed and cuts out the fan (mostly) and the roaring stops. If you don't hear the roar when you start up from a stop, with the A/C on, the clutch is probably bad, or the wiring has been damaged.

Charles

[mustang071]

And I thought I had problems. Thanx 'bobsallyh' and all of you for trying to help. At least I have some things to investigate now.

Happy Trails!

[bobsallyh]

On my 2003 Ram the evaporator freezes over the air won't pass. High humidity triggers it quickly. If I park the truck for 15 minutes or so with the ac off water gushes out the drain onto the asphalt.

[PA12DRVR]

If it always stops just short of Amarillo, maybe it just doesn't want to push that smelly air. 🙂

...although I guess the yards are actually East (???) of Amarillo.....

[BenK]

mustang071 wrote:
Our 2005 Ram 3500 Diesel (5.9) SRW has been a great tow vehicle for our 7-ton 5th wheel trailer. And after 150 thousand miles, three years ago we had to replace a couple of leaky hoses in our air conditioner. No surprise there. Since that repair, the AC blows cold and steady, towing or not. EXCEPT.

During this past year, on our last three return trips to Texas- one from the Great Lakes and two from Colorado- the blower quits working at about 350 miles from home. The AC is constantly cold, but without the fan blowing, we get very uncomfortable and downright HOT in the cab driving home in the Texas heat. In fact, on the last two trips, the blower quit in exactly the same place, a few miles south of Amarillo heading down 287 towards Dallas.

Each time, we’ve managed to get a little action out of the AC fan IF we can keep the RPM high as we travel. But if we stop at a red light and the engine is at idle, we get nothing. Cracking the window seems to help the blower also, but engine speed seems to be the key. Once on our last trip when climbing a hill, the tranny dropped to low and the fan started working perfectly as the RPM climbed to about 3000. But that lasted for about 3 minutes before dropping back into pathetic, weeny mode.

IMO...sounds like something in your alternator system. Key is that rev'ing the engine turns the fan back on.

Something is slowly over heating (that 350 miles time frame) and once at that over temp, it either adds enough resistance to lower the voltage and/or the alternator can't produce at that temp

Rev'ing the engine will make the alternator work a bit less hard, so it can produce the right voltage

Do a load test on your alternator

The Dodge House is clueless; they said the system only needed service which was performed prior to our most recent travel, but that had no positive effect on this fan problem. The AC works perfectly around town and all during the trip, except for the very last 350 miles.
Has anyone out there in RV land had this issue? If so, how did you fix it? Help!

[Durb]

Durb wrote:
Change your ignition switch cartridge. My 2004.5 had similar problems with erratic blower operation and that fixed it. Rather than using relays, Dodge routed the fan wiring and current through the ignition switch which overheats and ruins the contacts. The switch is less than $40 on Amazon and it takes less than an hour to install without special tools, very easy. There are some good videos on YouTube showing you how.

Before you throw a bunch of money at it, take 10 minutes and get on YouTube. Search - 2004 ram 1500 ignition switch - by Frugal Country Guy. He shows how to replace the switch in order to cure erratic AC operation. I had to replace my switch at around 75k miles.

[Huntindog]

Iraqvet05 wrote:

Huntindog wrote:

Iraqvet05 wrote:
I had a 2500HD that would stop blowing cold air at stop lights and at low speeds. The blower fan would still blow but the air was hot. It took me a few weeks of research but I found out the fan clutch had failed, causing the evaporator to freeze up.

I cannot fathom how that could be.
A clutch that doesn't engage with enough force (normal wear failure) will not pump enough freon to freeze the evap.

One that has locked up (Not a normal occurance) will be much more likely to freeze at highway speed... In fact most systems cannot make a evap freeze at idle. They just do not pump enough freon fast enough for this to occur.

Maybe freezing up was the wrong effect but the mechanical fan clutch in that truck was weak. On hot days, at stop lights that radiator fan clutch should have been screaming but it wasn't....no air flow over the condenser meant the condenser couldn't conduct the proper heat exchange and the result was warm air in the cab.
Similar thread here...fan clutch failure

My apology. I misread and was thinking compressor clutch... You are talking fan clutch.

Even so.... The symptoms don't jibe. A weak fan clutch will mean low airflow at low/idle speeds, and a hot condenser... Which will lead to high freon pressures on both high and low sides, and poor cooling. I do not see how the evap can ice up from this.

At any rate, it should still work great at road speeds.

A simple test, spray the condeser with water, and see if temps improve.

[mustang071]

Thanks 'srt20'! That sounds very plausable. I'm betting it's either that or the Aliens- as suggested earlier.

[srt20]

mustang071 wrote:
Thanks to all of you for the replies.

The Dodge Tech (thinking a freeze-up) suggested low Freon and serviced the system. Then said if the problem continued to stop and let it sit for awhile before restarting. We did all that, but it had no positive effect. And, as far as I can tell, the blower motor continues to run but the airflow diminishes to almost nothing at low RPM.

The strange thing to me is that it doesn't do this any other time except the very end of our trips. Why wouldn't it happen when we started out or during the entire excursion of two weeks?

Ok now we are getting somewhere.

Broken blend door. Take the blower motor out from under the dash. Screws will be facing down. 3 screws. Lower the motor, stick your hand up in there and feel for the loose plastic door, like a flap. Wiggle it out through the hole the blower motor was in. Replace the blower motor. And enjoy.

This door blends the outside air and inside air. So you will technically not have "MAX A/C" anymore, though on the dash it will still say its working.

The HVAC on these trucks have been kind of a wreck since day one. You can pay the $$$ to have it fixed like factory, but it will happen again.
Also, with the blend door gone, the fan will actually feel like its blowing harder, more airflow.
And lastly, if you put slightly more refrigerant in then what Dodge calls for, it blows quite a bit cooler air.

Been there, done that, on all of it.


btw, the blend door moving around in the HVAC is what is cutting off the airflow. As for it happening at certain times is just luck, or unlucky, lol.

[Iraqvet05]

Huntindog wrote:

Iraqvet05 wrote:
I had a 2500HD that would stop blowing cold air at stop lights and at low speeds. The blower fan would still blow but the air was hot. It took me a few weeks of research but I found out the fan clutch had failed, causing the evaporator to freeze up.

I cannot fathom how that could be.
A clutch that doesn't engage with enough force (normal wear failure) will not pump enough freon to freeze the evap.

One that has locked up (Not a normal occurance) will be much more likely to freeze at highway speed... In fact most systems cannot make a evap freeze at idle. They just do not pump enough freon fast enough for this to occur.

Maybe freezing up was the wrong effect but the mechanical fan clutch in that truck was weak. On hot days, at stop lights that radiator fan clutch should have been screaming but it wasn't....no air flow over the condenser meant the condenser couldn't conduct the proper heat exchange and the result was warm air in the cab.
Similar thread here...fan clutch failure

[Grit_dog]

beergardens wrote:
It isn’t clear in the original post whether the blower motor actually quits running, or if it continues to run but the airflow diminishes. Determining this is a key part of diagnosing this.

This.
It's either the blend door or freeze up, unlikely the fan just quits working specifically, not randomly and as evidenced by the OPs description, measures to create a vacuum in the truck to increase airflow work.
If the compressor quits working, the fan still blows air through the vents. But if the comp is cutting out then it will not be cold air.
Or, it's a super electromagnetic force in the exact spot on 287 that is kinda like a mini area 51 phenomena of super secrete alien research.

[ScottG]

Huntindog wrote:

ScottG wrote:
Sounds like low freon level is causing the evaporator coil to freeze up.
It will be worse when humidity is high or eng speed is low.

Highly unlikely. Low freon level would result in poor performance. The system blows cold. Therefore, the freon level is perfect, or close to it.

You may be on to something with the icing of the evaporator idea though. The system should have some sort of switch (probably a low pressure or temp) that cuts the compressor off to prevent this.
In my mind this is the most likely cause. The OP can test his theory out without any tools or even lifting the hood. When it happens, simply turn the AC of for a few mimutes. If it is iceing, then it will melt, then work perfectly when it is turned back on, until it ices up again.

I am not sure if this is a orfice tube or expansion valve system.

If it is an expansion valve system, then that may be acting up.
This is a more involved fix though.

I would look for a compressor cutout switch. They are cheap at 15.00 or so, and easy (5 min) to install.

Not only is it likely, the exact thing happened to me last summer.

[Durb]

Change your ignition switch cartridge. My 2004.5 had similar problems with erratic blower operation and that fixed it. Rather than using relays, Dodge routed the fan wiring and current through the ignition switch which overheats and ruins the contacts. The switch is less than $40 on Amazon and it takes less than an hour to install without special tools, very easy. There are some good videos on YouTube showing you how.