Mexstan

Has anybody had any problems with the A/C freezing up? Mine appears to freeze up often. I know that high humidity can sometimes cause this but this happens with the temp at 80-85 degrees and the humidity between 40 & 55%. Today it froze up with the temp at 82 degrees and the humidity is 43%.

The symptoms are that with the temp selector at mid scale in the blue range and fan at about medium, after a while the air volume out of the vents gets less and less. The air temp out of the vents also increases. If I don't do anything, after a while the dash vents get quite noisy and almost no air comes out. I have discovered that as soon as I detect that the air volume is decreasing to shut off the compressor but leave the fan on. Within 5 minutes the air volume increases and it blows really cold air with the compressor off. When this cold air starts to warm up I switch the compressor on again and normal cooling happens for a while.

I am guessing that the evaporator is freezing over and restricting the air. With the compressor off the ice starts to melt and the air flowing over the ice causes the cold air with no compressor.

If this is what is happening, how do I prevent this freezing?

spots

Is your drain opened? Do you have any debris on the evap? Are you sure that the evap is freezing and not a door malfunction? Next time this happens unplug the a/c pressure switch and leave inside settings alone. See what happens.

Mexstan

What do you mean by a door malfunction?
Doesn't switching off the compressor mean the same as unplugging the pressure switch? When I switched off the compresasor I never touched any other controls.

jphunter55

Freezing up is a symptom of a undercharged system, when you are low on freon or 134a, you have gas on both sides of the expansion valve which will lead to a frozen evaporator.

Haulin_in_Dixie

Capillary tube system, no expansion valve. Generally if the system does not cycle too much (too short of a time) the pressure is high enough.

Stan I would have someone put gages on it and check the pressures. There is another way it can be freezing up rather than the coil freezing. It can have some latent moisture in the system that was not removed in evacuating. This will collect usually at the capillary tube and block it, causing the warmer air. Shutting down the system allows the pressure to equalize, melting the ice at the tube. It then works fine until the moisture again collects and freezes.

These system with the capillary tube and operating by a pressure switch are generally real good at not freezing the coils. The pressure switch never allows it to get that cold before cycling. The moisture deal usually happens in the hotter days. Works real good at night but when the sun hits, starts to freeze. It's not supposed to do it and should be warranty stuff. Or is your warranty over?

Mexstan

Thanks for the input guys. I was wondering about the pressure but as I don't know enough about the system thought I would ask the resident experts. Y'all came thru again.
This should still be under warranty. Just have to figure out if I try to get it fixed down here or wait until I go north again. Will decide in a couple of weeks when some other things fall into place. In the meantime the A/C works well for short trips around town. It only freezes up after about an hour of driving.

spots

Stan try swapping a low pressure switch with someone else who has a Dodge. I agree with HID that this system if low on R134 would cycle alot. Does yours cycle at all?
By door malfunction I meant that the blend doors inside the dash were not working properly. Mine does it every now and again when I drive for a few hours in the rain.(I get floor and nothing else no matter where I put the controls.) Next morning it is fine. Only done it a few times.

CAKUZ

[QUOTE]Originally posted by Mexstan
[B]Has anybody had any problems with the A/C freezing up?
]
Mexstan;
My A C is doing the exact same way as yours. I can hear the fan/blower running but very little air is coming out of the outlets. Shut the compressor off for a few minutes and it is OK for a little while. The first time it did this I could smell a burnt odor . I shut the AC off for a few minutes and it has acted up since.
I also thought it was freezing up at first, but am not sure now. I am more inclined to think it may be the controls, (Switch) or the electronic/computer system.
I have gauges and AC tools and will check out the pressures, etc within a few days and keep you posted. Let us know if you find out anything before I do.
It should be under warrenty but the dealers service dept. around here are not very reliable. I saw on another thread, maybe on TDR site, where a guy having this same problem took it to his dealer. They had taken his dash apart 3 different times, damaged other instrument panel parts , replaced some parts, but still had not corrected the problem. He was pi***d big time.

handymantim

I also vote that it's low on freon.

If I understand you correctly, there isn't any place down there to get warranty work done? If so, ask your neighborhood mechanic if he'll throw his gauges on it for $5 and give you a reading. If it's low, go to Wal Mart (if you have one down there) and buy a can of R134 for another $5 along with the fill hose (10 bucks?). They also sell "deluxe" cans with a pressure gauge built in.

Good luck!

Mexstan

In theory I can get warranty work done at my local Dodge dealer, just not sure I want to trust taking it in to them for a day. I am seriously thinking of taking it in to one of the local automotive A/C guys and have them do a pressure check for me. They replaced a leaky evaporator on my wifes old Neon for a very reasonable price a couple of years ago. Will wait for a week or two before I do this as I have no time right now. In any case the A/C works just fine for short local trips. It is only on the longer trips that it acts up. Maybe by then CAKUZ will have finished his tests and I can use his info to rectify my problem.
Yes, we have Wal-Mart, Sam's, Costco etc etc but the Wal-Mart's and others do not carry the full line that is available in the states. No freon for sale here that I have ever seen.
BTW, a couple of hours ago drove from 13 degrees C to 31 degrees C in less than an hour. The A/C was very welcome as the temp started to go up.

md11jetdriver

Hey Mexstan:

I had almost the exact same problems with my 2003 ram. It started when I took it on its 1st extended road trip, 2 hours into the drive I noticed low airflow, higher noise and warm air. Pulled over and popped the hood and everything froze up. Took it to the dealer, they put the gages on it and found the system low on freon. They added a pound of freon and dye and sent me on my way and told me to come back in a month so they could check the system again. 1 month passed with no problems but I had only driven short trips. They checked the system and no leaks noted. A week later, I took the truck on its 2nd extended road trip and it happened again. Popped the hood, solid ice. Took it in the next day, hooked up the gages and the system was full with again no leaks noted. The dealer opted to replace all A/C lines, cappilary tube ect as he said a restriction was causing the problem. That was 4 months ago no problems since then.

patrick

I have Mexstan's same idenical a/c freezing up problem.I've taken it in twice for warranty repair,1st time the told me that it was a faulty condenser,it worked for a day,then froze up again.Took it back in,& they said it was low on freon,which they put in.This worked for while,& then started freezing on any lengthy trip.It works again when it defrosts with compressor off,&then back on.Taking it in, is a pia, for guesstimate work!Maybe this is like the old refridgerators that you had to defrost monthly,& they just have'nt told us. Pat

jd131313

Hey MEXSTAN my 04 is doing the same thing. I dont believe it is the oriface tube or why would the air stop blowing thru the vents with the blower on high?

On the older systems when this happened, it was the cycle switch. I caused the evaporator coil to freeze up hence no air flow out the vents. I don't know where the cycle switch is on the 3rd gens but if anyone does HELP I want to change it out.

Bill

kully560

there is a tsb for the fin sensor relocation mine froze up for almost a year until smoe people on this site pointed me to the fin sensor .the dealer looked it up and d/c gives new location .

Mexstan

Since taking it in to the dealer (Texas) in January it has worked just fine. No idea what they did to it but so far it has not frozen up once and both passenger and driver vents put out the same amount of cold air. As it was done under warranty I did not ask what they did and now I'm sorry.