Have any of you AC gurus tossed the expansion valve and installed a inline orifice valve.I know the compressor would need to cycle I can do that with a binary switch good idea or not I going from R22 to 134A.
The model of expansion valve that fits MCI wants 200 bucks and research says a orifice will cool better, if you believe the internet :o so am I thinking of having a orifice tube made and go that way IF it will work
Im no help on the orifice tube question, but I might be able to get you a better deal on the expansion valve--I deal with a couple of different manufacturers..do you have any kind of part#?.
Good luck
Where's Nick Badame????
Happy coaching!
Buswarrior
Cliff, Call Lamar at Welch Industries down in Georgia. He might have the answer. He works on all kinds at there shop. He just made a hose I couldn't get made anywhere down here in Texas and Prevost was no help.
Here's an example of a inline repair replacement. Sometimes the orifict tube would get jammed or damaged to such an extent that the tubing would need to be cut to remove the orifice and install a replacement piece. Several places have them. Don't know about different tubing diameter at fittings. You splice it in and install a new orifice. Also, don't have an idea of the flow restriction you'll need.
https://shop.advanceautoparts.com/p/factory-air-liquid-line-orifice-tube-repair-kit-w-o-orifice-tube-16150/5892090-P
Quote from: muldoonman on August 21, 2018, 06:28:58 PM
Cliff, Call Lamar at Welch Industries down in Georgia. He might have the answer. He works on all kinds at there shop. He just made a hose I couldn't get made anywhere down here in Texas and Prevost was no help.
I purchased my 2 Kiki compressors from Lamar he told me my compressors will work with either but without looking at my setup he didn't won't to give much advice lol and Georgia is long trip for me
Orifice tube will work fine if you can splice the repair kit in. You will also need a cycling switch to keep evaporator from freezing up. GM started to switch their vehicles over in mid to late 70's. They mounted the cycling switch on the receiver dryer tank. It threaded onto a male ac Schrader port. The switch had a small screw between electrical prongs to adjust if unit would freeze up. I think they kept the low side pressure around 28 to 32 with r-12. When converting over later years to r-134, it was not necessary to change switch or setting. Your compressor may draw more current that an auto ac model, so you might have the switch control a relay to cut the compressor in and out. The early years, the compressors would cycle frequently in normal operation. In later years, the system was matched close enough that they pretty much ran all the time. Now , they are using variable displacement compressors, and a smaller amount of freon in systems.
If you are talking about the main system in the bus I was told they are around 10 tons of cooling. No way could a orifice, handle that, between varying engine/compressor speeds and varying evaporator blower speeds you would have very poor refrigerant control and have major liquid flood back to the compressor under low load conditions. Stick with the TXV, you may be able to find a valve from a commercial HVAC system that would work for less $$
Quote from: kevink1955 on August 21, 2018, 08:25:49 PM
If you are talking about the main system in the bus I was told they are around 10 tons of cooling. No way could a orifice, handle that, between varying engine/compressor speeds and varying evaporator blower speeds you would have very poor refrigerant control and have major liquid flood back to the compressor under low load conditions. Stick with the TXV, you may be able to find a valve from a commercial HVAC system that would work for less $$
Nope it is my dash air,the 12 ton coach air was removed
Quote from: luvrbus on August 21, 2018, 05:36:42 PM
...good idea or not I going from R22 to 134A...
134a is not a replacement for r22. We just went through that in our 4108, and the shop used R438A25 R22, which is more commonly referred to as M099. They had to change the oil in the new compressor we installed so that it was the same as the oil already in our system. Not sure what oil you're currently running with the r22, so you'll need to check on that with regard to compatibility with the M099.
Apparently the M099 is used as a direct replacement for the r22, although at the moment the r22 is still available. Since we were installing a new compressor we opted to make the change to M099 now, not sure why you're contemplating making the change or if it's necessary in your case.
Regarding cooling with the M099...after a few miles down the road for the compressor to do its work compressing 25 pounds of refrigerant, the unit easily keeps the bus at 72 degrees with the single compressor.
Was your system working previously with the current setup? If so, then I'd put money that after all the costs to change the system you'll be spending as much as you would have to just replace the bad valve.
Clifford, Lamar is right! There are many variables in systems and no way to definitively answer your question. It's the same thing as when someone asks you can you install a turbo on a N/A 8V71. Yes you can. Will it work? Well, maybe... What pistons and injectors and timing and other stuff does it have? Then you can answer. Sometimes it all works fine and other times it all goes to pot. I wish I was out there to look at your system so I could pay you back a little for all the help you have given me.
Richard is right about 134A not being a replacement for 22.
There is a lot of engineering that goes into HVAC systems and transport systems are some of the most challenging because they need to work with so many changing conditions. I would stay with what the system designers used unless I made some major change to the system. If you are changing refrigerants/metering devices you need somebody who know what they are doing. You know what I mean, somebody like you are on mechanicals! Not some yahoo who knows enough to baffle you with BS! LOL!
I got out of the HVAC business some years ago but the basic physics don't change and my son is still in the business so i ask him about all the new refrigerants. Call me if you can't find a yahoo who knows anything out there. LOL!
TOM
I know 134 is not a direct replacement for 22 that not the question all hoses,o-rings,dryer,2 new Kiki 134 compressors,the system has been flushed, new condenser,motors, oil loops installed and binary switches.
The hang up is the r22 expansion valve MCI used at the evaporator feeding off the main coach air.I decided to spend the 200 bucks I am so deep into this 200 bucks is a drop in the bucket now. The price of the valve just rubbed me the wrong way :o.
I would have been money ahead if I had went with my first plan installing a RedDot unit with hydraulic driven compressor in the spare tire compartment 2 hoses and pump it would have been over with
If you have already setup the system for 134A, you should be able to get your local refrigeration distributor to build you a valve for 134A that would fit. Sporland and Alco both make modular valves. Just get a body with the right hose connections, add a cartridge for size and temp, and a 134A head and you are in business.
TOM
Tom I found out the expansion valve are made for a certain tonnage I never knew that before,I am close to 4 tons that should cool that sucker with the huge windshields