i added a full can, same problem. i'm going to be looking for leaks this weekend before adding more cans. i noticed when i removed the gauge that it had some yellow dye residue around the schraeder valve, so the previous owner obviously had a problem in the past. i'm going to do the black light thing and see if anywhere else is leaking other than the schraeder valve at the service port. is this a common leak point?

also, i was going to try swapping the pressure switch. can i just simply unscrew that? or will all the existing refrigerant come out? (i didn't know if there is some valve under it or not that cuts off flow if removed.)

 

Check the hose assembly that runs from the top of the compressor and has one hose going to the dryer and the other goes to the condenser. I recently had AC trouble of my own and I replaced my compressor, condenser and dryer and had the system recharged. It did fine for 2 weeks then I parked my truck on a Friday and did not drive it at all that weekend. Come Monday morning on my way to work, guess what....AC was blowing hot air and the compressor was cycling every 5-10 seconds.

When I got home from work I checked my AC with a UV light and did not find any leaks. Freon was way low according to the cheap low side gauge I had from one of those recharge kits. I tried adding a can of freon, it did not work. AC cooled off a little but was not cold at all. Since I saw no leaking UV dye I figured the only thing it could be was the evaporator, they are kind of a known problem on Dodges. So not wanting to tackle the evap myself and not having anyone to help me with supporting and removing the dash I took my truck to the local Dodge dealer. I also reasoned that if the dash and HVAC housing had to come out I wanted someone who knows Dakotas doing the work. The service guy said they charge a flat rate of $1,050.00 to R&R an evap and charge the system and I figured that price was more than fair. Next day they called to tell me the hose assembly had "a real bad leak". They charged me a total of $761.00 for diagnosis time, the new hose assembly and labor to replace the hose and re-charge the system. It took 4 days to get my truck back because the dealer had problems getting the new hose sent over from their warehouse in Orlando. To their credit the dealer did pay for a rental car for me to drive the entire time while they had my truck in their shop. That was 2 weeks ago, my AC is still ice cold now and I sure hope it stays that way.

And yes you can unplug and unscrew the cycling switch at the dryer. It has a Schrader valve so the freon will not leak out. Rather than using the UV light it might be better to get a leak sniffer tool from Harbor Freight, they cost about $70.00 or maybe you can rent one at a parts store if they have one. I sure wish I had done that because it would have saved me a lot of money on the AC hose problem. I think the sniffer tool does a lot better job at finding leaks than the dye does. Check both the valves for the high and low lines to be sure there is no leak there. I once had a small leak at my high side valve and it was cheap to replace. I had a wreck in 2010, the body shop overcharged my AC and I had a good local garage check it for me, they found the leaky valve and only charged my $20.00 for the part and no labor to replace it.

AC work is tricky. You need gauges and other specialty tools and the know how to use them to really do it right. Sometimes you can save money by replacing parts yourself and getting a recharge, other times you have no choice but to pay a shop to find and fix the problem.

Jimmy

 

What was the pressure? You REALLY CAN NOT do this work without the proper tools and that means a gauge SET. Not the can gauge. You need accurate pressures, hi and low, to properly diagnose a system.

 

Grab a set of manifold gauges at Harbor Freight and save yourself the headache of overcharging the system and ruining components. They are on sale a lot for around $50, maybe less with a good coupon

 

i've got a good gauge set, no problems there. after adding a can, i think i got the low side pressure up to somewhere in the mid 30's (can't remember the exact number). high side was below 200, again, can't remember the exact number. it was blowing as cold as cold could be (actually, TOO cold, i saw just under 32°F at the panel temps on low blower...which means the evaporator is even colder and i might have freeze up problems)(but one problem at a time). the problem is that after driving for awhile, the compressor just stopped cycling, and panel temps skyrocketed, just like before i added the can last weekend. the compressor will not come back on until i turn it off for awhile. air flow did NOT decrease, so despite my freezing panel temps, my evap was not freezing up at that point in time (at least to the point of blocking airflow). also, turning my temp **** slightly warmer also did not work, so i don't "think" it is turning off due to freeze control. another reason i don't think it is turning off due to freeze control is that my panels were NOWHERE near as cold has they are now before i added the last can, they were definitely well above freezing (i'd be very surprised if they were under 45°).

 

You could have a failing relay, or it is starting to sound like you have a leak or pressure switch/compressor problem, either a failing clutch or compressor. Try swapping the A/C clutch relay in the PDC in the engine compartment with the horn relay and see if the issue continues. If that doesn't work then I would lean toward a bad pressure switch or compressor.

What is the system pressure with the compressor not running?

 

Give us some exact pressures and the temperature you're testing at but if you're around 70 or so they don't sound far off.

Turning the heat up will not prevent the evaporator from icing up if you think that is happening. The air goes through the evaporator first then the heater core.

There is no "freeze" protection. The compressor clutch is controlled by the PCM based on the high and low pressure switches, that's it. There are no other inputs. The PCM can turn it off at WOT. There is a relay for the compressor clutch in the PDC.

A clutch can fail when it gets hot. Is the electric fan running with the a/c?

 

Kind of my thoughts here.

 

You could have moisture in the system if so it will ice up.

You may need to replace the A/C Receiver Drier / Accumulator has it ever been replaced?

I think the compressor is ok if hitting a high side of 200 psi

Check the clutch make sure its not shutting off on you meaning its worn out or going weak.

You may need to pull the Orifice Tube and check to see if its plugged up dirty.

 

I almost asked about engine temps before... what temps are you referring to when you say "panel temps"? I think I read somewhere the AC will stop working if/when the engine temp gets too high. Pretty sure it happened to me when my fan clutch needed replaced.