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How many oz of 134a to fill the OTR AC system

Yahoo Message Number: 81438
I will be installing a new compressor on my OTR AC system.
Does anyone know approximately how many oz of 134a it will take to refill the system?

Re: How many oz of 134a to fill the OTR AC system

Reply #1 –
Yahoo Message Number: 81442
On my 2001 Intrigue it took four pounds to fill the system when the compressor was replaced.

Richard Aquino

Re: How many oz of 134a to fill the OTR AC system

Reply #2 –
Yahoo Message Number: 81446
Thank you for the quick reply. Now i can arrange the evac and refill.

Dean

95 Magna 52880

Re: How many oz of 134a to fill the OTR AC system

Reply #3 –
Yahoo Message Number: 81450
The amount of refrigerant required , listed on the unit label is not necessarily exact. I have looked at a number of coaches , and they all had 6 lbs. You really have to have a refrigeration mechanic charge the system , getting the correct super heat etc. You also have to charge the system , in at least 75 to 80 degree temperatures, as charge is affected by ambient conditions. When you do this , the charge is too much for 50 deg temps and not enough for 100 deg temps. The label is only a reference as not all coaches have exactly the same length of hoses

Ron Baran 09 Magna 7025

Re: How many oz of 134a to fill the OTR AC system

Reply #4 –
Yahoo Message Number: 81471
You did not provide your coach info. Depends on the length of your coach, drier/accumulator replacement capacity and compressor. I had to replace a hose on mine about a year ago and was able to get the actual charge weight that the factory used from CC tech support. Original compressor still working....

Jim Hughes

2000 Allure #30511

Re: How many oz of 134a to fill the OTR AC system

Reply #5 –
Yahoo Message Number: 81475
Jim

Sorry for the oversight on coach info. Although most CC are 38 to 45 feet long which have the OTR system.
I do not know how to provide the drier/accumulator replacement capacity on this 17 year old rig and the compressor is a 488-45011 Zexel/Seltec compressor.
Do you think the prior provided estimate of @4 lbs is not reasonably accurate to keep the the service charges honest?

Thanks

Dean

95 Magna 5280

Re: How many oz of 134a to fill the OTR AC system

Reply #6 –
Yahoo Message Number: 81476
I have a sticker on my coolant recovery tank that shows my system has 4.5 lb's of freon plus 4 oz's of oil.

Barney

07 Inspire 52059 40'

Re: How many oz of 134a to fill the OTR AC system

Reply #7 –
Yahoo Message Number: 81485
Just Cut off the High side end on the compressor side Quickly and used two hose clamps I added 4-12 oz. cans and Gauge says 30/40 psi on low side normal Low side sweeting and blowing cool air did not looses any oil. Keep you posted Ken 99 Allure 30356.

Re: How many oz of 134a to fill the OTR AC system

Reply #8 –
Yahoo Message Number: 81489
Ken, I assume you did not evacuate the system with your method?
The 48 oz add back seems to indicate that you retained some refrigerant in the system during the compressor exchange.
I am replacing the compressor because the clutch coil failed, not the compressor.

Have you had success with this approach on other occasions?

Dean

95 Magna 5280

Re: How many oz of 134a to fill the OTR AC system

Reply #9 –
Yahoo Message Number: 81497
Dean,

My coach is a 40ft Allure and the servicing for it is 5lbs of R134a using 10.2 ounces of oil.
If matched with same type compressor, the capacity should be the same. Your dryer may have a tag on it and you can look up the capacity if not on the tag. Depending the capacity of the replacement dryer used, you may have to adjust the charge a few ounces. Using your gage pressures and air temps with system on max cool will give you a better indication for any adjustment. I have never found superheat and subcool thermocouple measurements work well with automotive systems because of the other heat sources from the engine compartment. I always used my gages, temp probe in the AC vent for air temp and scale to weight the R-134a.
I assume you are doing the work yourself? Remember to replace your office tubes and expansion valves if your system has them. If you had a fail compressor, it likely blew its guts into the system and it needs to be flushed and cleaned out. A good AC shop would have the equipment to do it. Otherwise, you would be wasting your money putting in the new compressor to only have it fail months later.

Jim Hughes

2000 Allure #30511

Re: How many oz of 134a to fill the OTR AC system

Reply #10 –
Yahoo Message Number: 81499
Dean,

Just noticed your post on clutch failure and not compressor failure. Is the clutch not replacable without disturbing the system? Most are. Some may require some special tools such as GM type. The tools are sometimes available for loan from a nearby auto parts store. Others types may only have snap rings holding the clutch on. Also, what caused the clutch to fail? Did the compressor possibly bind up? Also, did you verify that clutch coil is indeeed the culprit and not a low pressure switch? If you have a static charge still in your system, your compressor may be ok. Just trying to help you avoid overlooking something.

Jim Hughes

2000 Allure #30511

Re: How many oz of 134a to fill the OTR AC system

Reply #11 –
Yahoo Message Number: 81505
Jim

The AC clutch stopped engaging. The cause was a blown 20A fuse which only blew when the AC switch was on and the wire joined at the clutch.

Without the wire plugged in at the clutch, the fuse would not blow.
There were 3.4 Ohms at the clutch wire which should indicate a good coil.
The AC service shop declined to work further because of the electrical question even though I had traced the wire numbers and provided the electrical schematic for the system.
I took it home ran a 12ga jumper wire from fuse to coil bypassing the relay and OEM 12 ga wire. That blew the fuse and the coil no longer had 3+ ohms of resistence.
An 18 gauge wire would still trip the clutch coil direct from the battery but got very hot.

So, I sourced a new compressor for $200 and will install it myself.
That appeared to be more reasonable than trying to find a coil or clutch for the 17 year old compressor. I can get the tools to remove the clutch. But, now I have the compressor.

So the system will be opened when I install the compressor.
I tested the compressor electrical path and it did not blow the 20A fuse.

I will likely have the system evacuated and refilled by a shop.
I do not know what caused the coil to fail. But it appears I can get this thing repaired and working for about $400 vs the declining shop's estimate of $1000 (Including $450 to replace the compressor).
It seems most of the AC shops work by rote and the rules of the Kingdom of California.
Since the compressor did not blow, I do not think the system is contaminated. It was just an electrical problem. It cooled fine prior.
I am dangerous as prior to this I had no knowledge of AC cooling systems except for installing a whole house system in 1970 myself.

Dean

95 Magna 5280

Re: How many oz of 134a to fill the OTR AC system

Reply #12 –
Yahoo Message Number: 81511
Dean,

I suspect that once you change the compressor you could still have a clutch not engaging. Sounds like a relay or a wiring issue. I would first trace your circuit for any shorts and 12vdc as it goes through each component starting at the fuse panel. Disconnect the connector at the clutch. Good luck in your efforts. Let us know the outcome.

Jim Hughes

2000 Allure #30511

Re: How many oz of 134a to fill the OTR AC system

Reply #13 –
Yahoo Message Number: 81516
Jim, thanks for the advice. Hopefully I will not need those steps.
As previously indicated, I have already bypassed the relay, the AC switch, and the OEM wire and still blew the fuse with the old clutch.
I am hoping that since the new clutch engages on the new compressor without blowing the fuse that that issue is solved.

Dean

95 Magna 5280

Re: How many oz of 134a to fill the OTR AC system

Reply #14 –
Yahoo Message Number: 81527
Thank you for the hint.

I found my label and it says 8.71 oz of oil and 5 lb of 134a.

Dean

95 Magna 5280

Re: How many oz of 134a to fill the OTR AC system

Reply #15 –
Yahoo Message Number: 81531
Yes there was some pressure left when I recharged it. Did a trial run no leak at the cut off hose end but lost Charge again found out looks like freon now escaped behiend Comperssor clutch rotor shaft seal, Removed Rotor half on clutch and spotted new oil leaking on mount also now. Looks like a trip to the A/C Shop Leak down Vac. test and maybe new compressor and Dryer. Will have it looked at in Yuma this winter. We will run the generator roof air when needed.I got rid of my A/C Tooling. Will make a post in the future on findings. Ken 99 Allure 30356.

How many oz of 134a to fill the OTR AC sy

Reply #16 –
Yahoo Message Number: 81466
Again, a coach model would help

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