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Hfg59 · 08-13-2015, 11:10 AM

On 2006 40 FDQS how many lbs of freon to charge ac with 134 a

BFlinn181 · 08-13-2015, 12:50 PM

It's surprisingly less than you might think, only a bit more than an auto A/C system. If you can't find a sticker on compressor or near the valves in front, I'd consult with the chassis or air conditioner manufacturer. To properly fill, you should use a complete A/C manifold gauge set to monitor high and low side pressures against temperatures. A shop can do it, make sure oil is correct and proper, and also check for leaks. Better to pay a little to have it done right than overfill, under lube, or constantly have to fill because of a leak. JMHO

jerry davis · 08-13-2015, 01:13 PM

Just had mine done. Took right at 4 lbs

SteveS · 08-13-2015, 03:30 PM

Interesting...did mine early July and it took 6 pounds.

BFlinn181 · 08-13-2015, 03:47 PM

Steve S, you got too much, I think. Here's Evans Tempcon's list of capacities, they make many of the RV dash HVAC systems we drive. Their greatest capacity is 5.5 lbs.

Evans Tempcon, Inc

DrDaveMA · 08-13-2015, 06:01 PM

Hfg59, Jerry Davis has a late year 2005, it should be the same as your 2006, Steve has a 2001, go with the 4 pounds, same as Jerry.

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SteveS · 08-13-2015, 06:58 PM

Bob - Surprising how much difference there is between various systems. Perhaps my system was overfilled a little...I did look at the machine that evacuates the A/C and re-charges it and it was a fraction under 6 lbs when the tech stopped. He used the pressures and temp readings to determine when to stop filling. Seems to work well now though. Thanks for posting the various system loads...comes in handy.

By the way, I did tell him initially that I thought it took 4 lbs. based on checking with a local RV repair shop. He put that amount in and it didn't seem to cool at all.

BFlinn181 · 08-13-2015, 07:07 PM

Since you had a pro do it, I'm sure he put in the proper amount. Doing it in the driveway, with only a can mounted low pressure gauge is a way to over or under fill the system. With 134a, over filling reduces cooling as much as under filling. The first time I worked on my system I was surprised at how little more it required than an auto or pick up truck system. I thought the long lines from front to back would require more than that actually required.

Hfg59 · 08-13-2015, 08:11 PM

Thanks everyone. I was at a shop,I don't have gauges we just couldn't find it posted anywhere on the coach. When we charged it up it took a little over 4 lbs but we discovered a leak on one of the hoses where it hooks on the compressor. I assume the hoses are one piece from front to back so I'm trying to find a hose shop that can crimp a new end on the hose without taking the hose off the coach. Don't know if I'll have any luck. Thanks again

SteveS · 08-14-2015, 11:52 AM

Hfg59 - When you put 4lbs in, was the system completely empty or did it take 4 lbs more than what was already in? Curious about how much it actually holds. Like I said previously, mine took a fraction under 6 lbs after it was evacuated. And like Bflinn181 says, overfilling will reduce cooling capability as much as under filling...actually from work I was involved in before retirement, depending on the system size, I found that overfilling can reduce cooling capability more than an equivalent under filling. Thanks.

Hfg59 · 08-14-2015, 07:41 PM

The guy at the shop put five 12oz cans in which is 3.75 lbs. He thought it was close to being full according to his gauges. About that time we discovered the bad hose fitting so we stopped. It was the first Motorhome he had ever worked on so he was kinda in the dark on how much to put in, but he said he could get close with the gauges. Anyhow he couldn't help me with the bad hose an we decided it was more than either of us wanted to tackle as far as removing 40 ft of hose. I've got an appointment on the 24th with A&H automotive in okc. Actually Dell City Ok. Dash ac's in diesel pushers are suppose to be one of there specialties. They come highly recommended. I will see what they say an get back to you.

Hfg59 · 08-14-2015, 07:42 PM

Yes with the leak it was completely empty when we started.

poppopc · 08-14-2015, 08:01 PM

Our dash air was only 2#!

sandy1 · 08-14-2015, 08:55 PM

On the early alpines with the wax valve there is not any interface between radiator fan and dash a/c. When you start your engine check to see if your radiator fan is turning ( approx 350-400 Rpm) If not the a/c tech needs to put shop fan in front of radiator so air will flow across a/c condenser, if not gauge pressures will not be correct.. Compressor head pressure will go to high. There is a fix in the hydraulic line to the wax valve to have radiator fan always be in the idle speed mode and then increase speed when needed for cooling. This oriface can be obtained from Source engineering for about 30-40 dollars. Doing this will ensure that air is always flowing oven A/C condenser and keep pressures within normal ranges