Hey gang..
I was curious, is there there a setup in which I can charge up my A/C on my '98 Ram 5.9 SS/T. This truck has been awesome and I've NEVER had to repair or touch the a/c system. But, I believe it may be getting low on coolant. So, is there anything I can do myself that will replenish the system? I'm also curious, is there a fault indication of a low-pressure situation? I see there's a servicing port on the passenger side.

Thanks in advance..

The fitting in the pic is the high-side fitting; charging is done through the low-side fitting below and to the rear of the air cleaner inlet duct.

The only really correct way to charge the system is by weight (the amount is on a decal under the hood) and it helps to have a gauge manifold/hose set (available cheap from Harbor Freight) and the pressures on the gauge set will tell if the charge is low.

With the manifold set you can top off the charge by temperature/pressure but it's not as precise as by weight.

if it's r134, you can get a can and a gauge from any auto parts store. crank it up, turn the air on high connect the gauge and follow the directions. pretty easy and straight forward. they make refrigerant with dye in it, if you think you have a leak, and want to look for it. the can and gauge set costs between 25-40 bucks, depending on brand. once you have the gauge, you can use it on any car with r134 and a new can. fyi, once you install a can on the gauge/filler, it has to stay on, or you must use it all. if you take it off, the remainder of the can will come shooting out, all over the place.

Most refrigerant can tappers have a shutoff valve so you can use part of the can and then shut the valve...problem is most tappers will leak off the remnants in the can in a short time.

the parts store stuff, for the price listed, usually consists of this setup. once you tap the can, you either use it all, or leave it connected. if you take off the valve/gauge/hose assembly, the can rapidly vents the rest of the contents into the air. for a one time deal, this is the cheapest way to go.

I use the hose kit with gauge. You can re-use it with a new can of refrigerant. Usually if the coolant is low, the compressor will short cycle. With AC on, you can see the gauge go up for 5-15 seconds then it drops off. If it is really low, it won't come on at all. I usually add enough refrigerant one can at a time to get it running smooth. No more. too much can damage the compressor. If it takes more than one can, it has a pretty good leak.

I do it by temperature, put a thermometer in the A/C duct and roll down the windows. Otherwise, it'll cool off the cab in short order and you won't know what you get. If I can get the air coming out to be less than 39 degrees I call it good. It's bad to overfill R134A.

R.

this kit does have a gauge on it, just not a fancy one. it displays pounds, and has a color coded sweep around the gauge, showing low, correct and high pressures. for the guy thats going to fill his truck once in a lifetime, it's a good deal. and, you can screw any of the cans onto it. on an r12 ride, i go to an a/c place and give them the refrigerant. the guys here will pull it out, and leave you with a vacuum in the system, so you can go home, add your oil, and add the refrigerant. not a bad deal, really.

More than likely, the evaporator under the dash in the heater box is leaking. Its a real common problem, and usually when you have the box out, the smart thing to do is do the evap and heater cores at the same time. Its about a 5-10 hour job depending on your experience to swing the dash out of the way to get the box out.

For the moment, try one of the cans as suggested above and see if it fixes it. If you can go all summer and not have to worry about it, then its a small leak. A/C systems are like brake systems, they either leak or they don't. Also, make sure they can you add into the system has dye in it, this will help a technician find the leak later on if you choose to have someone fix it for you---or you can buy a UV light to see yourself where the leak is--unless its in the heater box. No way to see that until its apart.

Also, check the condensor up front to see if it has any staining on it running down it. This would be the oil in the A/C system dripping out. Not uncommon to have road debris puncture it--even slightly.

If its leaking from a hose, sometimes that is harder to find, the dye can help here, and again, look for accumilating dirt clinging to the oil leaking out. There is no warning lights to indicate low A/C refrigerent, a low pressure switch shuts off the compressor if there isn't enough refrigerent and a high pressure switch shuts it down to keep the sytem from self destructing with to much pressure.

Hope that helps some.

If a '98 truck is just now low on charge I wouldn't consider it anything but "normal" leakage.

Charging an R134 "by guess and by golly" isn't a good idea, a gauge set and can tapper would be the minimum equipment needed.

you really should evacuate the system and see if the vacuum holds....if it does your good to refill....I would at the very least replace the orifice and the dryer....the right amount of refrigerent & oil and you should be good to go.....if you know an ac guy.....a freon sniffer can save you a ton of time and money as well if it doesn't hold the vacuum

Rickster