Filling dash AC system

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Filling dash AC system

August 22, 2021, 09:30:14 pm

Anyone know how much Freon I need to fill the dash AC system on my 99 U320 36 ft.

Re: Filling dash AC system

Reply #1 – August 22, 2021, 09:58:49 pm

Capacity for all coaches is 5.0 lbs or 80 ozs of R134A beginning in 1994.

Dash Air Conditioner Refrigerant and Oil Capacity

Re: Filling dash AC system

Reply #2 – August 22, 2021, 10:00:54 pm

Parker 3520-016 Receiver dryer
8 Lbs 134a in our coach is what reduced evaporator temp to minimum for me
Scott

Re: Filling dash AC system

Reply #3 – August 22, 2021, 10:06:59 pm

Not very scientific but, I added until I started losing dash temp and that was with the low side reading 20 psi.

Re: Filling dash AC system

Reply #4 – August 22, 2021, 11:16:24 pm

Quote from: dsd – August 22, 2021, 10:00:54 pm

Parker 3520-016 Receiver dryer
8 Lbs 134a in our coach is what reduced evaporator temp to minimum for me
Scott

I really don't think it's 8 lbs of refrigerant, a 40-42 ft rig usually fits 5 lbs or 80oz. Oversize dryer would only increase capacity by an ounce or two. 5 lbs is quite a bit, most pickups only take 2- 3 lbs. 8 lbs would be overcharged and it won't cool well. if you could even get the system to take in all that extra refrigerant. The change from liquid to gas is what makes cool, if there's too much liquid, it can't change state and no cooling effect will happen.

Re: Filling dash AC system

Reply #5 – August 22, 2021, 11:43:44 pm

Quote from: Digger337 – August 22, 2021, 11:16:24 pm

I really don't think it's 8 lbs of refrigerant, a 40-42 ft rig usually fits 5 lbs or 80oz. Oversize dryer would only increase capacity by an ounce or two. 5 lbs is quite a bit, most pickups only take 2- 3 lbs. 8 lbs would be overcharged and it won't cool well. if you could even get the system to take in all that extra refrigerant. The change from liquid to gas is what makes cool, if there's too much liquid, it can't change state and no cooling effect will happen.

Yes I couldn't believe the amount. So using a digital charging system I added 1/4 pound at a time and watched evaporator temperature and pressure were 15/275 keep adding till I actually was 9 pounds and temperatures weren't decreasing so I reduced back to eight pounds. 20/325 psi. 50 deg at 105 outside air temp. Last week running down the road was seeing 40 deg up in Ely back to Boulder City so I'm happy with what I got, but I completely agree a LOT of Freon. I will also state that I absolutely am unsure of the accuracy of the recovery system I'm using in regards to the digital scale. Overcharging r134 will quickly over stress the system and should be avoided. If you don't have access to a recovery charging machine you should have serviced by someone who does. The receiver dryer I mention is the same 12cu inch as removed.
Scott

Re: Filling dash AC system

Reply #6 – August 23, 2021, 05:27:58 pm

Quote from: oldguy – August 22, 2021, 09:30:14 pm

Anyone know how much Freon I need to fill the dash AC system on my 99 U320 36 ft.

This link to Sanden compressor, which is usually used in the ft motorhomes and other. I think this is the best information about ac systems I have ever found. It contradicts what many ac service professionals have told me about oil capacity, how to add it and how to determine exact amount needed. It's also a component test procedure like I've found no where else. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.sanden.com/productlibrary/manuals/SD_Service_Guide_Rev_2.pdf&ved=2ahUKEwjV34L7hMjyAhUIXM0KHWcUCJIQFnoECAgQAQ&usg=AOvVaw1tI8v08Sc1MbnalbjuYz2w
Let me know what you all think.

Re: Filling dash AC system

Reply #7 – August 24, 2021, 10:53:29 am

Quote from: Digger337 – August 23, 2021, 05:27:58 pm

This link to Sanden compressor, which is usually used in the ft motorhomes and other. I think this is the best information about ac systems I have ever found. It contradicts what many ac service professionals have told me about oil capacity, how to add it and how to determine exact amount needed. It's also a component test procedure like I've found no where else. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.sanden.com/productlibrary/manuals/SD_Service_Guide_Rev_2.pdf&ved=2ahUKEwjV34L7hMjyAhUIXM0KHWcUCJIQFnoECAgQAQ&usg=AOvVaw1tI8v08Sc1MbnalbjuYz2w
Let me know what you all think.

Outstanding information. Would be nice if we had manuals for everything like this.
Scott

Re: Filling dash AC system

Reply #8 – August 24, 2021, 11:37:35 pm

Followed y'all's suggestions of 5 pounds and it works great for my 96 U270 36'
We are in north Texas and it's 100 degrees everyday now. Did evacuate the system first and purchased 7 12oz cans. It will take 6.6 cans. Cools great but just wish the air flow from evaporator was better. Also looking to add some dash mounted fans to circulate air more on hot afternoon drives. Also had to replace the condenser fan relay. Relay would engage but contact burned.

Re: Filling dash AC system

Reply #9 – August 26, 2021, 11:39:17 am

My dash air never worked after purchasing a coach 3 years ago. Yesterday guy came late in the day to diagnose and fix it. First he vacuumed the system down although there was no freon left in the system and was able to hold vacuum for five minutes without changing. He next put in 5 lb of freon based on what I've read in the forms. There was no tag or anything anywhere to tell him. Cost me about $330. At the conclusion I had 40 degree air coming out of the register at the dash. They also put in an UltraViolet dye so if there is a leak I'll be able to find it with a UV light. I'm hoping this fixes my dash air problem because driving down the road without it in the summer is no fun
I thought about buying all the tools and equipment necessary to do it myself but really I don't have a whole lot of knowledge when it comes to this stuff otherwise I've done my reading and figured it would be better to just have somebody that knows what they're doing do it. I make come to regret that decision if this stuff leaks down again and I have to pay another three hundred bucks to refill but hopefully if there is a leak it will be found.
I still have a problem with my temperature control switch. There's seven wires on the back of that and nobody knows why. At least nobody that I've been able to talk to. I'm told that almost all of them have only three wires. When I was at fot couple years ago they told me they didn't have any more of those switches and the soldered wires directly to the back since there was a broken connector but the switch doesn't work as it's supposed to not sure why and I don't know how to find a replacement.
Still looking.

Re: Filling dash AC system

Reply #10 – August 26, 2021, 11:57:16 am

Vacuuming down the system is necessary it the system is empty to remove any
moisture. I have changed all the fittings in the rear of my coach as they where all
corroded. The original fittings were all aluminum and now the are steel. I will be filling
up my system in the next couple of days. I can fill my system but I don't have a vacuum
pump and my cousin has one and I will be there tonight.

Re: Filling dash AC system

Reply #11 – August 26, 2021, 12:23:53 pm

Bob, that switch with 7 wires also controls the dash heater and that valve is only accessible from under the front of the coach. Look for the heater hoses going in and out of a plastic valve. and multiple wires going in it. Just to the center of the coach from the right above the headlights.

Re: Filling dash AC system

Reply #12 – August 26, 2021, 12:43:11 pm

Quote from: craneman – August 26, 2021, 12:23:53 pm

Bob, that switch with 7 wires also controls the dash heater and that valve is only accessible from under the front of the coach. Look for the heater hoses going in and out of a plastic valve. and multiple wires going in it. Just to the center of the coach from the right above the headlights.

Thanks Chuck good to know. Any idea of where they get that's switch from? Instead of stopping n2n Mine just goes round and round and round sometimes I can get it to adjust temperature and other times it doesn't seem like it does anything at all.
Next time I go on to the coach so I'll look for that fitting you're talking about.
Need to rebuild my front six-pack soon.

Re: Filling dash AC system

Reply #13 – August 26, 2021, 03:28:41 pm

That's why I did the headlight change when I did so I could get at the valve.
I was able to fix the valve but I can't remember what the problem with it was.

Re: Filling dash AC system

Reply #14 – December 13, 2021, 04:15:43 pm

Just changed the condenser and dryer and replace the hose going from the dryer to the condenser there was oil dripping out of the old hose green I did some research on the forum and what I read I should be add some oil about 3 to 3 1/2 ounces I also had someone tell me not to add any but what I read I would lose about 1 oz in the old dryer and about 2 ozs in the old condenser I have two questions if someone can help
Can I pour the oil in to the new hose before connecting it to the dryer or should I vacuum it in on the high side and what type of oil and grade? 10 or 20 For this older couch (I read what type but have to look it back up)it's the grade I'm Concerned with it 10 or 20
This repair job has been going on for a couple of weeks waiting for parts so the system has been open to the atmosphere so how long do I vacuum it to get the boil the moisture out so I can add the Freon 134a about 5lbs 80 ounces I understand
I've read and Watch videos but can't find the answers

Re: Filling dash AC system

Reply #15 – December 13, 2021, 04:46:44 pm

I used PAG 100 it is the medium viscosity. PAG is the required oil for R134

Re: Filling dash AC system

Reply #16 – December 13, 2021, 05:02:35 pm

Takes 30 minutes of vacuum to get all water out. Better to get a can of oil and let the system suck it in then charge with the freon. Hopefully your new dryer hasn't been open to the air for a week. Depending on the humidity where you are could be bad.
Larry

Re: Filling dash AC system

Reply #17 – December 13, 2021, 05:21:04 pm

It has Larry I installed the dryer on the frame and had trouble with the old hose so had to wait for a hose and I guess I didn't know better and it's open in a garage no humidity but probably damp with the rain we been having but open on one end to the atmosphere for about a week just got the hose today do you think I should order a new one

Re: Filling dash AC system

Reply #18 – December 13, 2021, 05:24:07 pm

The last coach i charged was contaminated by the dryer being old and was decomposing and had also plugged the expansion valve. You mentioned changing the condenser was that for corrosion? Follow the compressor recommendations for charging oil type if you changed it. Having a Freon servicing machine that you can recover with is real nice. R134a went up in price a bunch the last time I ordered some. Ordered two 30lbs cans thinking the price would be around $130 each and was billed for $350 each. So some of the low turn over suppliers may still have at the lower price. Worth checking IMO.
Scott

Re: Filling dash AC system

Reply #19 – December 13, 2021, 05:30:38 pm

Dryer might be ok just do one hour vacuum instead of 30 minutes to be sure. I've seen body guys leave them open in a dirty shop and they still worked, just better to always to keep sealed till hoses are on.

Larry

Re: Filling dash AC system

Reply #20 – December 13, 2021, 05:32:16 pm

Book will probably say to change it. I keep sealed till I'm ready to install. Last dryers I purchased had a desiccant indicator on one of the plugs. Nice touch. Anyone's guess

Re: Filling dash AC system

Reply #21 – December 13, 2021, 05:34:53 pm

Amazon.com: Universal Air Conditioner RD 8214C A/C Receiver Drier : Automotive

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Filling dash AC system

Reply #22 – December 13, 2021, 05:45:13 pm

If the receiver/drier has been left open for any significant length of time then I think it would be best to replace it. At least that's what I would do.

Re: Filling dash AC system

Reply #23 – December 13, 2021, 05:54:45 pm

Scott I change the condenser because the Finns had swelled out from rot and stopped the fan from turning , had it checked on the road this summer so they vacuum it out for me because I didn't have a recovery machine at home , I ordered a complete unit condenser ,fan,and dryer from Foretravel and had it shipped to Canada. Installed it myself but the dryer was mounted up on the frame of the coach, so for it to fit to the long hose coming from the evaporator I had to remount it on the frame . I am a newby at refrigeration and didn't realized that the dryer had to be kept sealed as much as possible.which I went to automotive school in the 70s I am a red seal auto mechanic here in Canada and they probably taught me that in school but Ac wasn't my field and that was many years ago in the pass It's been open to the atmosphere for a good week now in an enclosed garage if you think it's ruined it maybe a good idea to change it if I vacuum it for a hole day would it dry it out

Re: Filling dash AC system

Reply #24 – December 13, 2021, 06:16:54 pm

I would still use the drier and pull a vacuum which would remove any moisture. Couple of hours should dry it out but a longer vacuum wouldn't hurt anything. Recommended to keep the drier sealed until ready to install to keep trash and moisture out.My dash ac blows 32 degree air consistently in the desert and have seen it dip below that on occasion. I need the colder air because in 96 and older the systems volume of air was less. I keep a produce probe thermometer in my vent and when it doesn't blow in the 30's I tweak. I check periodically with an infrared thermometer..Having as many units as I've had over the years I know that to have one this old to blow this cold is unusual but no complaints from me as it gets mighty hot in my part of the country and points southwest where I frequent.

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