freon

In the dash AC or the roof top?
Dash can be done with gauges by someone who knows how to read them, roof not so easy.

Roof top A/C Unit is sealed...no ports.
Ports can be added but typically not cost effective...ID/Isolate leak, fix leak, add valves, vacuum containment, add freon.....labor/material $$$

RV roof top A/C Units basically throw aways

You cannot check freon, it's outlawed by the gummit.

If it's a rooftop:

1. Clean it. Cleaning the "indoor coil" (the evaporator) requires taking some of the internal shrouding (what you see when the plastic cover is off) has been removed.

2. Leave the plastic cover off, and run the A/C to cool your coach. After an hour or so do this:

a. Measure inlet and cold air discharge temperatures inside the coach. Somebody will have a better spec, but look for discharge to be considerably colder. Say 80 in and maybe 60-65 out
b. On the roof, gingerly feel the refrigerant lines at the compressor. Discharge (smaller one) should be uncomfortably hot. Suction (larger one) should be cold, maybe sweating
c. Measure compressor amp draw with a clamp meter and compare with Running Load Amps (RLA) on compressor label. Should be close if voltage is around 115-120. If low, either failing internal compressor valves, or refrigerant is low. If high, compressor is probably failing internally (shorted windings, binding bearings).
d. RESIST the urge to put "bullet ports" on it to test with a gauge set. THEY LEAK! If you didn't have a freon loss problem, you soon will.

Danford50,

As others have said, if you're talking about the roof A/C's, they're sealed and you can't do much.

If you're asking about the chassis A/C, you can purchase a gauge set. BUT...you have to know what you're doing to make sense of the readings. The gauge readings depend upon refrigerant charge, ambient temperature, humidity, temperature of cooled air, etc. There are usually performance graphs available which will confirm if the A/C is performing as designed for any given temperature/humidity situation.

Assuming you have a fairly modern unit, you'll need a gauge set for R-134 refrigerant. If it's an older unit you'll need a gauge set for R-12. If it IS an R-12 system, it might have a site-glass on it. This can usually tell if the refrigerant charge is sufficient.

Most automotive stores will sell the gauge set (two gauges and three hoses) for between $50-$100.

It's also a good idea to use proper safety gear (safety glasses/full face shield and gloves) when working on the system, and a good analog thermometer to measure outside temperature and to insert in a vent inside the vehicle to measure the output air temperature.

Good Luck,

~Rick

there is no law prohibiting you to check the gas in a vehicles a/c system. it is against the law to let it escape into the atmosphere. so if you have the proper gauges and skills. there shouldn't be a problem....

SidecarFlip wrote:
You cannot check freon, it's outlawed by the summit.

Added freon to the 85 Mercedes recently using OTC can with mini gauge. R-134A

I still have R-12 for an older system also, send the feds....LOL