2nd Gen Non-Engine/Transmission A/C questions

[BILLVO]

Sorry I am a stickler for leaks. Whether you can see them or not. If there was still pressure in your system you should not have to vac it down. There are several different kinds of vac systems the cheapest is an air operated venturi type. the next is an electric vac pump and then the reclaimer, charging units. A leak can be a simple few cent o-ring or schrader valve. easy to repair at a shop versus expensive freon every so often. I say at a shop because they can evacuate the system to recover the freon that is still in it then only charge for what they have to add. Maybe you know someone that works for a shop or owns a recovery machine.

 

[SSabick]

Where could one find these vacuum kits?

 

[B.G. Smith]

Where could one find these vacuum kits?

Heres one, the http://da.harborfreight.com/cpisearch/web/search.do?keyword=vacuum+pump-------------the others can be found at HVAC dealer. I have seen some at pawn shops but you never know what you are getting. They get pricey, especially the recovery units. bgs

 

[Bob4x4]

Heres one, the http://da.harborfreight.com/cpisearch/web/search.do?keyword=vacuum+pump-------------the others can be found at HVAC dealer. I have seen some at pawn shops but you never know what you are getting. They get pricey, especially the recovery units. bgs

That air driven unit is VERY noisey :-laf



Bob

 

[E7mack96]

while were on the topic

I have a 2000 Pete that the AC has worked flawlessly in for the past 2 years. Last week, the driver said it quit cooling. When he got back today, I hooked up guages. Static was good, with the low side sitting about 80 psi and the high side just a little higher.



Once I fired it up, the pressures seemed ok, running about 25-30 psi on low side, and around 200 on high side. The temps wont pull below 60-63 degrees. The compressor keeps disengaging when i think it shouldn't. The pressures arent pulling too low.



THe driver called back tonite and stated that the temp guage i left in the dash is at about 80 degrees now too. He is in near 100 degree heat in southern GA already. He is going to Miami to deliver in the AM.



I did check and clean the evaporator filter. Evaporator has no clogging on itself either.



Is it possible that the oriface is clogged a little?

 

[BILLVO]

E7mack96



I have seen numerous orifice tubes break off. yes this can cause a low or no cool situation. if it plugs up the pressures will be very eratic most common is low side will go into a vacum. or low side will flicker wildly. On a Pete is the fan clutch working properly is the driver running it on auto or manual mode in those conditions it should be running almost continuosly either way. I would have the Rpm of the fan checked with a photo tach your pete dealer should have the spec for that it will vary depending on what engine you have. you may have a bad temp switch to kick the fan on. is it an oil or air engaged fan clutch?if air check for air leaks.

 

[E7mack96]

Yes, the fan engages based on engine temp just fine. It engages on the ac too, but if the fan is engaged too long, as in going down the road pulling 150,000 like we do, the ac compressor cycles constantly, and is disengaged most of the time.



At idle, if the engine fan is off, the system seems to work like normal. but it is not cooling down to an ideal temp.

 

[BILLVO]

Yes, the fan engages based on engine temp just fine. It engages on the ac too, but if the fan is engaged too long, as in going down the road pulling 150,000 like we do, the ac compressor cycles constantly, and is disengaged most of the time.



At idle, if the engine fan is off, the system seems to work like normal. but it is not cooling down to an ideal temp.

The engine fan has to be in the manual ON position to do an ac check at idle or up to 1000-1200 rpm if you are not getting any air movement through condensor it will not cool properly. Do you have gauges on ac when this is happening if the orifice tube is plugged a bit it can cause high pressure switch to kick ac clutch out.



Boy at 150K I'm glad I don't have to buy the overload permits. What do you haul heavy construction equipment?

 

[DSiemens]

I hooked up a guage set and have the following readings



low side pressures are about 20ps. High side about 250psi.



It seems my high side is way too high for this. What is the logical checks to perform next?

 

[BILLVO]

Does the compressor cycle at regular intervals or does it cycle fast. Are your gauges reading steady not jumpy on high or low side? what is panel temp?You may have an orfice tube plugging a bit. Is the accumulator freezing up when it is running this may be plugging also.

 

[E7mack96]

Yes, We haul stuff like D9 Dozers, 345 Excavators, and military Tanks (battle tanks).



We do have the manual override on when checking the pete.



On my Ram, the air has never worked when stopped in traffic. I just got around to hooking some guages up to it. THe high side goes to 475 psi before the high pressure cutout kicks in. when the high side goes this high, the low side goes to near 100 psi. THe condensor temps go to over 200 degreees as well. Vent temp is in the 80's (bacisally outside air temp)



If i spray some water onto the condensor, to simulate cooling effects of airflow, the temps run at 150-170 on high side, and low side runs 27-30 psi. The air out the vents will cool to the mid 40's.



I do believe that the fan clutch in the ram is not working at all, and never has because, since new it has not cooled at idle in really hot weather. My durango has always done the same, after multiple trips to dealer and it never being fixed yet.



Is there a pressure/temp switch to make the fan clutch engage, or should i mount a small electric fan to the condensor?



THanks,



E7

 

[Grizly]

Thanks guys , found my problem with a/c kicking off was that when compressor got hot the clutch would slip found that they get a gap between plates after time, that lets this happen because they have put in 2 washer like spacers in between clutch plates I then removed these 2 washers and put back together and never has kicked off yet... . hope this helps some one having same problem. .

 

[SDrake]

E7mack96, I observed the samething on my truck, the first time I saw the gages go to 475PSI I instinctively jumped out of the way expecting a safety popoff to blow like I experienced on a 1975 Mercedes. But nothing happened and air was working normally as I drove around town. Normal for my truck is that cooling is kind of weak in stop and go traffic and plenty cold once cruising.



I concluded that the fan clutch was weak, couldn't remember when I last hear a good fan roar on staT up. I changed the cooling fan clutch and got quite a bit of fan roar when I first start up but it settles down after about a block of driving.



One day recently I was observing the pressures while charging and heard the fan clutch let go ( air roar stopped) and within 10 seconds the high side pressure climbed from 225 to 475.



I picked up a shop fan I had and held it in front of the radiator and immediately the pressure began to drop. It was educational to watch the high side pressure respond so much and so quickly in response to the air flow to the radiator.



Our trucks need a auxiliary fan in front of the radiator in order to have good in town cooling, plain and simple. I have been looking for one that would fit our trucks. Anybody done auxiliary fan for the condenser coil?

 

[DSiemens]

The pressures seem stable on the low side. The high side goes between the 220 to 250 point.



Is their a test that shows which is blocked? Do you rip into it and replace anyhthing that might be the problem?



How would pressures be too high with a failing clutch?