charging dash AC unit

ALL motorhomes built since 1996 will have 134a in the system.
The ONLY way to know for sure you have the correct amount of 134a in the system is to drain and then fill with the amount of oz's/lbs that is required for your specific system. If you want to add 134a because over the years a slight amount has leaked out, you really need to connect the HI and LOW side to a set of gauges. You then slowly fill while watching the gauges to make sure the HI side does not get over 275 to 300 psi. You CANNOT use the dryer sight glass to watch the bubbles. A correctly charged 134a system will still have bubbles in the sight glass. IF you have (you really need one) a digital thermometer, you can stick it in the closest cold air discharge on the dash(usually the pass side). With a fast idle (1500 rpm) charge the system. have someone watch the Thermometer and YOU watch the gauges. When the AC reaches the saturation point, the thermometer will start to raise in temp. STOP when that happens. You have reached the full level. Doug

1.5 LBS 134A WITH NO AUX CONDENSOR FANS
2.0 LBS IF YOU HAVE THE 2 AUX CONDENSOR FANS.

You really need a charging gauge set. That way you getting a reading from the low and high side. You can get a loaner from Autozone. There is no way to tell you how much to put in. Too much can cause system to not cool , just like too little does not cool.

This one indeed should have 134-A in it from the factory. My recommendation would not be to simply use a single gauge deal from a parts store and try to shove more refrigerant into it. Overcharging is not good for them and doesn't work any better than under charging. It's always good to have two gauges to see low pressure side and high pressure side. If it is significantly undercharged, then the compressor may not kick on due to the pressure switch not being satified. Often it is difficult to get them to take refrigerant if they are in this condition. You can jumper the switch.....but at this point a person ought to be thinking about getting it checked by a professional. I do all sorts of things myself...including air condition charging. But I took some time to educate myself a bit on it. ALL the components on our air conditioning systems can cost quite a bit. Just my thought on it.

The fittings are different. Impossible to put r12 in a unit requiring r134a, and viceversy (lol...)

If it cools (and the compressor cycles on and off), but not cold enough, one of those kits may do the trick.

At least in theory, these systems are sealed. The do not "lose" Freon. Like brakes and power steering and automatic transmissions, the big question is, if it lost fluid, where did it go?

A/C systems use a lubricant mixed in with the Freon. When they leak, the lubricant (and the dirt that was attracted to it over the years) leaves a mark. Look at all the hoses, fittings, and connections. Dirty black area = leak.

Depending on how bad, filling it up may still be an option. For the longest time I had to put a can in my jeep every spring...

rockhillmanor wrote:
I was under the understanding that you can no longer buy freon 'legally' without a license?
http://www.epa.gov/ozone/title6/608/sales/sales.html

From your link:
Therefore, HFC refrigerants such as R-134a, and HFC refrigerant blends that do not contain an ozone-depleting substance, such as R-404A and R-410A, are not currently covered under this sales restriction.

Most automotive AC systems have been using R-134a for the past decade or so.

rockhillmanor wrote:
I was under the understanding that you can no longer buy freon 'legally' without a license?

There are many different products used for refrigeration and all are commonly referred to as "freon". Some are still consumer legal and some are not.

You need to first determine what is in there NOW so you can know if the off-the-shelf refills are compatible or not.

Then you need to determine that you won't be just wasting your time and money. Most setups have a sight glass somewhere to observe the liquid flow and tiny bubbles while it is running.

OTHER THINGS CAN CAUSE POOR COOLING.....and recharging it wrong can end up being an expensive mistake.

I was under the understanding that you can no longer buy freon 'legally' without a license?
http://www.epa.gov/ozone/title6/608/sales/sales.html

rgatijnet1 wrote:
Most of the charging kits include a gauge where you add freon until it reads in the "green".

x-2

Most of the charging kits include a gauge where you add freon until it reads in the "green".