134 conversion

[Len Silva]

Got a problem in my motorhome that I hope someone here can help with (still a bus nut though).

The driver's air in my '94 Vogue has quit.  A little history....It has been converted to 134 but a half-assed job at best. They apparently just changed the compressor and adapted the access fittings.  It doesn't have a receiver/dryer.  It wouldn't hold freon for more than 200 miles (but didn't leak down when sitting for several weeks).

The last trip, the compressor seized up and threw the belt.

I contacted Kysor to ask about what compressor to use.  They weren't much help but did say I needed to replace the expansion valve and receiver/dryer and probably the hoses.

There's the big problem, the hoses.  How can I tell if the existing hoses are 134 compatible?  Replacing these hoses would be one major headache, they run in the frame rails with huge access problems.

It seemed to cool OK when it worked but the compressor just looks so small, about 4" in diameter and maybe 8" long including the clutch and pulley.

Any help is greatly appreciated.

Thanks,

Len

[TomC]

Don't worry about the external size of the compressor, Freightliner compressors are compact Sandens. Is your motorhome rear engine?  If so might be easier to run copper pipe for most of the distance since R134A is a smaller molecule and tends to leak through older hoses. 
What is needed to change from R12 to R134A- need to remove the compressor and change the oil to the R134A type; change the receiver dryer (all A/C's should have a receiver dryer to keep the freon dry); flush the whole system with Nitrogen; change the charging fittings.  Changing the expansion valve is not necessary.  My '84 Mercedes was changed this way, and works well.  Except R134A tends to put out more heat in the condenser.  Good Luck, TomC

[kyle4501]

FWIW, the last a/c compressor I changed had a requirement that the receiver/ drier AND the expansion tube (or valve) be replaced or the warranty was voided. There should be a rec/drier on your MH somewhere - must likely in an inaccessible spot.

My understanding is that 134a & moisture will mix in a system to form a corrosive mix to eat holes in the components. That's why cleaning the system out is so important for long term success.

I agree about replacing as much as you can of the hose with copper or alum pipe. 134a requires a 'barrier' hose to restrict the leakage thru the hose (like helium thru a balloon).

Good Luck

[Len Silva]

Thanks guys,

If I run copper tubing, what type fittings should I solder on the ends for connection to the hose?  Are they standard pipe thread or something special?  It may prove easier to run tubing than to replace the hose.

Len

[Tony LEE]

If the compressor quit soon after the conversion, it may be they did a quick and dirty job and didn't flush out all of the old oil. Apparently there are serious compatibility issues that lead to the "Black Death" tag for some of the conversion kits on the market.

[Nick Badame Refrig/ACC]

Hi Len,

The hoses only need to be replaced if you find them leaking refrigerant. Yes, R-134A will tend to leak in older rubber sooner then the newer hoses but,

I have done many conversions with years of service without leaks on alot of 1980's & 90's cars and trucks. If your compressor siezed up, it's most likely that they

either didn't properly charge the compressor with oil, or they could have over charged the system with refrigerant, or simply didn't evacuate the system.

It sounds to me that your install mechanic is your biggest problem..... Get your compressor and have it installed at a reputable shop. It's not rocket science....

The tibs about R134A and moisture are not correct. There should never be any moisture mixed with the refrigerant, period! Your system has to be evacuated

down to a 30 inch vacuum to eliminate all and any amount of moisture or contaminates. If this procedure is skipped, then yes, you will have problems with not

only corrosion but, the system will also freeze the slightest amount of moisture and clog the expantion valve leaving you with a restricted system. Locate your leak

point and have it repaired. It sounds like you have a leak on the high side by your description of leaking less when the system is idle.

Good Luck
Nick-