2nd Gen Non-Engine/Transmission AC HELP Please !!!!

[Bunyan]

OK, AC on max ideling temp in center dash vent is 50 degrees, as I speed up to the limit from 50 to 70 mph the temp rises to 60-63 and stays there. What could be the problem? I did a search and did not find anything with these symptoms. Any help appreciated. Going out of town on a long trip tomorrow, need advice. Thanks in advance, Ron

 

[ttbird]

Truck going on 8 years old. Sounds like you have lost some freon charge. Probably a slow leak, since it's kind of working. I don't know if you are able but you can buy a can of freon with a simple gauge and fitting to connect to the low pressure port to temporally recharge system for your trip and then find the leak later. I recharged mine every spring for about three years til it finally forced me to find the leak. Tom

 

[ttbird]

Forgot some info. Parts store should have the can I'm talking about. Air compressor has to be running when charging and low side pressure should be around 40-45 lbs. The gauge I've seen has green, blue(cold), yellow and red zones, as well as pressure readings. Can't remember the name of product but I've bought it thru out the country. In Houston when I was there for Ike.

 

[fest3er]

Evaporator may have become too dirty over time and may not be exchanging heat very well.

It may be hard to hear at idle, but you should see engine RPM drop when the A/C compressor engages. If it cycles the compressor too frequently, you may simply be low on R134, in which case one can may be more than enough.

If you have a 'cheap' parts-store low-pressure gauge, you should see the low pressure (suction) cycle between about 45PSI (compressor just turned on) down to about 25PSI (compressor just turned off). In olden times, Dodge A/C systems would find a steady-state between 23PSI and 45PSI and not shut off the compressor; talk about refrigeration!

A/C on my '98 hasn't worked well in many years (didn't even work well in '98 when it was not quite a year old). Lately, I put in enough R134 to get it to stop cycling so often; I don't even bother with gauges. Then it produces cold, dry air nicely. Some day it might be worth evacuating the system and checking the orifice tube. Or simply replacing it on general principle.

Of course, this now makes me wonder if there is a check valve in the system somewhere that is supposed to prevent freon from flowing backward once the compressor has been shut off... .

 

[Missouri Mule]

Check to see if recirculation/fresh air door is shutting when on Max.

My a/c as been working fine except when the high pressure switch went, that was about 7 to 9 years ago. I used to get 42 degrees air out of middle vents until the new switch now I get 48 degrees somtimes 42 when I have it on Max. I don't recall having to add freon of course I will have to knock on wood now.

 

[Bunyan]

I may have the answer. Last night I spoke with my diesel mechanic and he told me that if the fan clutch was bad it could cause the ac temps to rise do to lack of air being drawn in by the fan. Well this morning I checked the fan and clutch, it has lots of wobble. It's a good thing he mentioned it and that I did check it. I don't know how long it would have been, before coming apart. That's how bad it is. I'll replace it today and give an update with the results. Ron

 

[Joe Mc]

If the line behind the air filter box sweats typically it's cooling. Whoa! Clutch fan wobbly that could = big money if it came off . . . get back to us on results.

 

[Bunyan]

Replacement of the fan and fan clutch did nothing fo ac. However, less noise and less vibration from engine. Glad to find the fan clutch bad now before major damage. I'll have the mechanic check ac with gauges tomorrow. I'll update when I know more.

 

[DieselDoghouse]

Playing monday morning QB— to me it doesn't make sense that the fan clutch would be involved since the fan should be giving you your 50°F at idle - road (ram) air should take over (you mentioned mph so you're moving) under way!!

Start with you 'r' charge and also time the clutch cycles to see it the pressure switch might be bad. Otherwise could be anything from condensor, compressor, to orifice tube - further testing awaits!!

 

[DStarkey]

I am very interested in what you find... my '99 just started the exact same thing... very cold temps at idle but they get progressively warmer with higher engine rpm's. I took it to a local shop, and they can't seem to find anything wrong. Next stop will be an a/c specialist in the area...

 

[Bunyan]

Well guys, the freon was 5 oz. low. The mechanic evacuated, vacuumed, charged, and put dye in the system. This was Friday and cold air is back, 38 on max. Have not located any leaks at this time. I'll see what happens. Thanks for the help. I'll update if any change occurs.

 

[Joe Mc]

Since about 2004 I've had to give her a little juice every other year to keep her cooling well. I ain't pullin the dash to do the evap until I absolutely have to.

 

[DStarkey]

Took the truck to "Ice Cold Auto Air" (one of the better a/c shops around here). They duplicated the issue of no cooling over 1500rpms, and they called me to come pick it up... they have no idea what the problem is. They said they suspect it is a body control module, but there is no way to confirm without replacing a non-returnable part. This morning I took the truck to another a/c shop after explaining the situation to them. Frustrating.

 

[Beast2B]

i had mine evac & charged a couple years ago. the mechanic said something about dodge trucks having trouble with the o-rings at the condenser... anyone concur with that? i also add a few ounces each year to get it cold for the summer months

 

[Bunyan]

I've also have heard of the o-rings. I've heard that if you can pull a vacuum for up to 18hrs, in some instances, the o-rings sometimes reseal themselves. Hope you can figure it out.

 

[JRS]

My low side pressure port weeps freon from a bad seal. Purchase a good quality cap and lube the rubber cap seal with some AC oil. I haven't had to re-charge in two years.



The clutch on my engine fan was out too, but changing it made no difference in cooling. I purchased two small (8") fans from Summit and mounted them in front of the condenser coil. Yeah, it was a tight fit with the hood closed, but what a huge difference sitting at a light at idle! Also, I insulated the whole freon line from just downstream of the orifice back to the firewall. I put the insulation seem at the bottom of the tubing (6:00 position) so if any moisture builds up it will drain out. Also put additional silver foil insulation on the portion of the freon line that travels right by the turbo outlet to block the radiant heat.

 

[DStarkey]

I dropped the truck off at the fourth repair shop today. This one was recommended by the local Cummins repair shop as doing quality electrical diag work. Hope this one can tell me what is wrong...

 

[DStarkey]

So now it appears that the fourth shop has actually performed a diagnosis, and it seems that the problem is the compressor clutch. It is slipping under the load of the higher rpms, but it can hold at low rpms. I still can't believe that it took 4 shops to catch this...

 

[DStarkey]

New compressor is installed and cooling great. I guess the original unit didn't owe me anything at 181k miles...