JARHEAD

The A/C on the 01 workes fine most of the time. But it will seem to warm up and then cool back off. Seems to be getting worse. Anybody know where I should start on the troubleshooting?? I have not checked my pressures yet.

Kip

micah

this is exactly the problem I have with my 01. It will be blowing cold air, and then I'll start to notice humidity creeping in, and the air getting warmer. There is no pattern to the amount of time it will be running or not running. There were times last summer, when it would quit running for 10-15 minutes at a time. Not cool when it is over 100 outside.

I've taken it in 3-4 times now and each time they are not able to track it down since it is so intermittent.

I've kind of thought it seemed related to running and then coming to a stop, but it also does it going down the highway, so I don't know. I'll certainly be interested if you come up with the fix, and I'll be sure to post the same if I find one.

bnold

Mine has been doing the same sort of intermitant thing nice and cool then like humidity was taking over.... I recharged the system at the beginning of the year so I suspect I have a leak somewhere... Has to be a small one though because it worked fine for months. I'll check the level again this weekend to see if it is full or not....

scuzman00

Has anyone checked the controls where the heater valve is controlled?? If it is vacuum operated, the valve feeding the heater core may be bleeding water thru and causing the heater to overcome the A/C. Just a thought, otherwise the system may be low of refrigerant and the pressure switch on the compressor is opening out until the refrigerant warms up (expands) and then re-closes, thus causing short cycling.

Gary

bnold

Thats what mine was doing at the beginning of the year, prolly doing the same now... Any idea how to check for a leak that is THAT SLLOOWW? I guess red dye and let it sit and run trace the lines the best I can?

scuzman00

Dye will not always show up. Usually the compressor seal at the clutch assembly is where they leak. You will never see the dye where it comes out of there unless you shoot some fluorescent dye in and examine it with a high intensity blacklight. I think I saw a kit at Wal-Mart once that came with the dye and a light for around 40 bucks. A sniffer is your next best leak locator but they are WAAAAY expensive for a one time kinda thing (unless you have a buddy in the A/C service business).

Good luck in finding it!!


Gary

keithp777

I had the same issue in my 99. I checked the pressure, & saw it was fine. As I was looking at the guage, the A/C shut-off, so I knew it was not low.

Here is what I did that worked:
Locate the A/C Dryer near the right firewall.
Disconnect the Low Pressure Sensor on top of dryer.
Take a paper clip, cut off the end, so it looks like a "U"
Insert into the plug that geos into the sensor.

If that works, your sensor is bad. If that does NOT work,

Locate sensor just above the compressor
do the same as above:
Disconnect the Low Pressure Sensor on top of dryer.
Take a paper clip, cut off the end, so it looks like a "U"
Insert into the plug that geos into the sensor.


If THAT works, then this sensor is bad.

these sensor have a limited lifespan, and are fairly inexpensive to replace. The only expense is recovery/recharging the system.

Paintpusher

I had the same thing happen to mine, all that was wrong was low on refrigerant. A/C servicer said that in the winter when the rubber seals on the system shrinks, the coolant will seep out throughout the cold months. He also said that Dodges are most notorious for this problem.

micah

That is not the problem we (at least I) are discussing. If the system was low, it would continuously cycle as stated above by scuzman00. The problem I, and it sounds like others are facing is the A/C will run fine... maybe even fine for a few days... great even. But then one day, randomly the compressor kicks off and the humidity starts to creap in, followed by the warm air. the compressor will remain off for a random amount of time, sometimes a few minutes, sometimes 15-20, and then it will come back on and may stay on for a few minutes, or 15-20 or... and it continues.

The best suggestion I've seen/heard so far seems to be in what keithp777 posted. You can bet I'll be out there taking a look at it this weekend, if I don't get to it after work sometime this week.

As stated above, I have had the truck in a few times and the charge has tested just fine each time. I've had every suggestion from fan clutch (did I mention it happens even while going down the hiway sometimes?) to new comressor, but i'm just not willing to throw parts at it. I want to know that the money I spend is going to fix it.

By the way, the seals do not shrink just because it is winter, they do this because they get their lubrication from the refrigerant. When it is cold outside, you could go months at a time without runnng the A/C so they dry out.

scuzman00

As far as seal shrinkage goes, most A/C compressor to clutch shaft assemblies utilize a ceramic style seal. Rubber, viton or neoprene would not hold up to the rotating shaft loads. At least all of the GM compressors I have torn down are built this way. Just my .02 worth of worthless info....LOL

Gary

RAM2940

When you bypass the low limit and high limit switches using a paper clip the compressor should run continuously, no cycling, if it does cycle or cut off you have other problems. When you charge and test the a/c system chyrsler service manual says to put a jumper across the low limit connector to keep the compressor from cycling. My truck also has a slow leak, I can put a can in and it will last all summer, next spring it will short cycle or lock out on the low limit switch.

coalburner400

Most likely unrelated but just to add:

The AC needs air to pass over the exchanger. If your sitting in traffic it will not get as cool unless the fan is moving enough air. Again, most likely this is not your problem but check and make sure your puke bottle (or absence there of) has not clogged up air flow.

J BODY

Scuzman has posted alot of good info. I'm to the point when I talk to customers that "have to have it charged once a year...." that if they are under some kind of warranty they get a compressor. Just did one yesterday that I had recharged and died about one year ago. Unfortunately the compressor runs about 570 bucks just for the part, so I leave it up to the "out of pocket" guys on what they want to do.

Coalburner also has a very valid comment. The hotter it gets the more a perceived "my a/c is not as cool at idle" problem will arise. Perfectly normal in most cases. Not to get off track too far, but that is the nice thing about the newer DR trucks. The gas trucks have a separate fan condensor assy and the CTD has an ECM controlled clutch fan that greatly helps cab cooling at idle compared to our 2nd gen BR/BE trucks.

If your a/c is working fine one day....and then suddenly quits and works ok again. If you can catch it try hitting the low psi transducer with a screwdriver (little tap will do). Transducer is the switch on top of the accumulator. If the compressor starts working like it should that may be your culprit. On those who mentioned vacuum assist in the air box, the 01 truck we are discussing here has an electric actuator for door temp control. It has a plastic adapter that can sometimes crack and the door will not function properly (temp won't change).

JARHEAD

Just wanted to re-visit this post from a few months back. What my truck does now is at idle, the a/c is half way cool. It will actually warm up on acceleration. Once settled at cruising speed, then it will cool down. This is sorta weird. Any ideas are appreciated.

Kip

micah

that sounds to me like the fan clutch.