Ok i'll start this.
It's getting to be that time of year when we switch on our AC and nothing but hot air. I know my Evap core is bad and need to replace it. Where do you get them? Should i just get it from Autozone or is there a better place. I think i'll do the heater core while in there too.
Anyone know where the thread on pulling the dash out is?

 

I paid $ 117.00 for my core at the Dodge Dealer when I had 65k on the clock.
I now have 173K on the clock, so I guess they did something better. The installer sprayed something on the core before installing it and cliamed it would help with the corrosion on the lower end of the core? I had three pin holes in the original core. None were close to the bottom of the core.

Cost almost $700.00 to get the job done.

Dave

 

Mine has been leaking for 3+ years. The leak finally got bad enough that I was spending $10/week to keep it full, so I put dye in it and rigged up a UV light from home despot parts. Now it doesn't leak anymore. I don't know whether to love it or hate it.

I won't replace my evaporator unless I start going through 1 can or more a month of r134 (adding oil of course).

 

My AC blows hot this year as well. I figure the compressor is shot, but how do I tell? I can see the clutch engage, but the compressor cycles for just a few seconds and quits. I heard that there is a high pressure cut out, so perhaps that is the issue?? I don't really have the coin to do major work on it, since I need to do a tranny rebuild/swap, but the family can't be asked to sit for hours in a black truck, towing the 5ver to go camping with no AC. The wife would not be happy!!

 

I'd be willing to bet, most of the problems with AC systems up north is the lack of operation in the winter months. This leads to dried out seals and leaks. Nothing to do with the Evaporator. I've been told one should operate the system once per day just to keep the oil moving around in the winter.

I use mine almost everyday for real, and nock on wood have not had any problems for a long time. My Son's 96 still has the original AC compressor in it.
Go figure. Truck has 280K on the clock.

Dave

 

Just go to your local auto parts store and get a recharge kit. They aren't too expensive. When mine was going out i would have to add about 1 can every 2 weeks. I knew when my evap core was bad when i charged it got in the truck and could hear it hissing out under the dash.
If your compressor is cycling it is working probably just needs a charge.

 

I would agree, except that the compressor is designed to cycle every time the DEFROST setting is used. In Iowa, I use DEFROST every single day all winter long, and I can hear the compressor cycle on and off. With lousy winter diesel, having the A/C compressor cycling on and off constantly, it is yet another blow to the MPG department! So, I don't really believe that my not running a dedicated A/C setting in the winter should be an issue, when the DEFROST is used almost constantly. As far as I know, my compressor is also original, with 210k on the clock. I haven't researched what actually goes bad in a compressor, either. Since I can see the clutch engage, I figure something is working, but if a valve or something inside is stuck or broken, maybe the compressor is actually shot??

 

The high pressure cut out switch is a possibility. Although, my compressor runs for about 20 seconds and cuts off. The in line filter between the compressor and dryer may be stopped up. You won't get any cooling if that is the case and in most cases, the compressor is coming apart. With the mileage your have have on it, I'd say you've done really good.

My first one went at 55K. Evaporator at 72K, Second compressor at 130K. On the third one now.

The only way to tell is to evacuate the system and remove the filter (orfice tube) and see. Don't know if its true but, everyone says you'll need to renew the Dryer, 100 bucks, and of course the oil and freon after pulling it down. No guarantee the compressor will not stop up the orfice tube again soon after you do this. It really does not make any sense to do all this and not change the compressor and flush the system out with compressor oil.

Your right about the defroster use in the winter. That is most likely why yours has lasted as long as it has.

Dave

 

zulusafari, mine did exactly the same thing yours is doing. From the sound of it, I doubt its the compressor. There is a pressure switch that shuts down the compressor for protection.

I would first check your LP, "good" should be in the 25 - 35 range depending on ambient temp., yours maybe minimal. Get a refill bottle, probably one large (16oz) can and most of a small can (11oz?) which is what mine took. It will only pull from the can when the compressor engages, so it may take a while on the first (the compressor will eventually cycle for longer periods). Check your presure after the first can to see if its stablilzed (i.e. when compressor is on it will drop) your target is level pressure in the previous range.

To find out if your compressor is DOA, check your highside port (I forget the ranges, maybe around 135-150?), if its pressurizing, that shouldn't be the problem (which you should find out after filling).


Read on for useless rant. When I first went to find out what went wrong on mine, I opened the HP and heard a low level hissing. Thought that couldn't be good, and started looking for the schraeder valve. Woops, not there, seems Dodge didn't want to use a removeable valve stem, nor removeable valve (welded to the tubing). After I filled the system, I went again to test the HP side, opened the cap and got a shower of 134a, seems the leak was bigger than I though, quickly screwed it back on and decided to stick with the cheap fix But at least its ice-cold again


cheap fix - B/C of my leak, and the presumably exhorbitant cost to fix, I just refill it at the beginning of the season.

 

The compressor will also short-cycle if the freon is low.

 

I would like to know as well. I have the same problem and would like to do the install and have the ac shop do the fill etc. I was quoted $700 last summer for the evaporator R&R.

 

Thanks for all the advice guys! I didn't mean to hijack the thread, but it is good information!! I will try to do the testing this weekend.

 

These trucks have the worst A/C I have ever seen, the evap core design is bad in my opinion. This past week I did a ton of work on the A/C system. I wish I knew about this spray on stuff to help corrosion before I did the install. There was so much corrosion on the evap core mine when I replaced it. I also replaced the drier and the orifice line and am about to install the freon. While I was in there I replaced the heater core and heater hoses as well. I also used this opportunity to finish installing dynamatt all over the firewall since this was the only place that did not have it. My truck is quieter than a 3rd gen inside, AMAZING.

I went to get some new compressor oil and there was low, med, and high vis. oil. Which kind do our trucks call for?

 

Dash removal threadhttps://www.dieseltruckresource.com/...d.php?t=106921

 

Anyone know what the normal cycle time is at idle? It does seem to be cycling about 10 seconds or so. I too run either defrost or AC all winter to keep the moisture content lower in the cab. Now, my AC is cool not cold even after a half hour run. I figure it is low on r134 but I don't have the equipment to test it out. Years ago, GM used to have a very crude sight glass off of the compressor's high pressure line. If you saw bubbles when running the AC, it was low on freon. Didn't tell you how low you were, but was good for diagnosing the most obvious problem.

Thanks,
AJG617