Originally Posted by timjet
I have had issues with my Dash Air unit ever since I bought it 4 years ago. It never works for more than 8 months. The first time I took it in they replaced the compressor, condensor and dryer. Next time the compressor failed and it was replaced under warranty. Next time a leak but they couldn't find it so put marking dye in. Never found it for 8 months . The last 2 times I took it in they said the shrader valves were leaking and replaced and recharged for $350.
I've taken it to 2 different repair shops over the years.
So now I'm going to learn how to recharge the system myself. I've never done that so any guidance would be much appreciated. I'm going to replace the shrader valves since I suspect that may be the issue again. How do I determine if and where a leak could be?
I feel your pain. I too have been through a couple of service centers for the dash air in our '04 Itasca Horizon 36GD with the CAT C-7 330HP. And, like you, they keep wanting to replace parts and re-charge, usually to the tune of $300 or more, each time. Well, mine lasts only the first day of a trip, then, the next day, IT'S WARM!
So, I too have decided to take on the task of at least recharging my own system until I can figure out just what I need to research a leak or problem with our system.
Automotive air conditioning is a complex system. Not only that but, the outside ambient temp and humidity plays a part in charging and recharging a system. There is, for the most part, a HIGH PRESSURE SIDE, and a LOW PRESSURE SIDE in these systems. The method of charging is technical but, not rocket science.
One of the best things you can do is cruise on over to youtube and look up Freightliner chassis A/C charging. There you will find plenty of examples on procedures and methods. You will, as has been suggested, need to purchase some equipment. I looked on Amazon and there's tons and tons of what's needed there. But, I took the easy way out and cruised down to our local Harbor Freight tool store.
There I picked up a brand new set of A/C charge gauges with hoses etc. I also picked up one of their vacuum pumps, the lower cost one since it will do the trick for my application. One more thing that I needed was not in the gauge kit from Harbor Freight was what's called a "Can Tap". H/F sells that item seperately. It's what's needed to connect todays self-sealing R134 cans to the yellow hose you'll be using with your new kit.
Now, when a system has depleted itself of all refrigerant, it often also *leaks in* outside air which, contains MOISTURE! Moisture, as has been stated, is not good for the operation of the A/C system. Sooooooo, this is why a VACUUM pump is needed in prep for charging your system.
If you purchase the two H/F components I have, the operation instructions will be right there in the kit. And, also as stated, Youtube is a good friend here. Watch one or two, at least a couple of times to get the basic picture of the operations.
Now, just because you purchase equipment needed to basically bring your A/C system back to life, doesn't mean it's gonna stay working correctly. YOU, like ME, HAVE A PROBLEM with our systems, which is why we're talking here. And locating a leak, in my case, 36' of motorhome and your case, 40' of motorhome hoses and fittings, is not an easy task.
When it comes to purchasing R134A refrigerant, you can buy it all day long in multiple places, in smaller quantities like 12 oz. cans, including one of the cheapest sources, Walmart, for around $4.88 a 12 oz. can. But, you and I, cannot purchase it in BULK form, with a large container, due to the fact that we're not licensed A/C techs with the correct badging and tech numbers. Soooooo, I pick all mine up at Walmart.