A/C Conversion help needed
 

Been working on A/C 134A Conversion, Serpentine belt setup with R4 compressor (6oz ester oil added), Replaced Evaporator with 1989 model,- flushed out and added new orifice valve, Cross flow Condenser 1995 model (also flushed out) also had orifice valve, left it out... A new Accumulator.... System Charges up fine but high pressure runs up after a couple minutes and throws the belt.... Would putting the orifice valve at the condenser make the difference? it would be flowing across it in the opposite direction...Any help would be appreciated ....Thanks. Ed.

Re: A/C Conversion help needed
 

If you are throwing a belt on a serpentine system, I would look to the tensioner. You only need 1 orifice tube, the condenser you have may have been from a Suburban with rear air? Are all your pulleys lined up? Did you get and use all the bracing?

Re: A/C Conversion help needed
 

The orifice tube is just that, a tube. Usually the larger screen will point toward the compressor. Operationally, it shouldn't make a difference.

GM moved the orifice tube to the condenser to address the equalization noise when the system shuts off. I pretty sure, Suburbans with dual air, kept it in the evaporator inlet.

How high is your pressure going? I assume you have the inlet and outlet of the condensor hooked correctly if your asking about moving the orifice tube.

Re: A/C Conversion help needed
 

I'm pretty sure you should be using PAG oil and not ester oil. I upgraded to serpentine on my 350 and switched to a R4 compressor. Most compressors come charged with the correct type and quantity of oil. If I remember correct ester and PAG are not compatible and R4s w/134A use PAG. I will check my emails from Vintage Air's tech support and verify my memory is correct.

Re: A/C Conversion help needed
 

MARK NTN ..I think the condenser came from a 1995 GMC pick. Serpentine belt is lined up and well braced...Bigdave160...the Evaporator did come from a Suburban, I may have hooked the condenser up backwards, does that make a difference? I don't know the high side pressure, I am the parts replacer. and only know a enough about this to get me in trouble.

Re: A/C Conversion help needed
 

I checked my old email and confirmed, R4 compressors take 8oz. PAG 150 oil. I never paid much attention to how the condensor was plummed, I'll get back to you on that.

Re: A/C Conversion help needed
 

Typically the high side gas from the condensor goes into the top and liquid comes out the bottom to the metering device(orifice)which feeds the condensor.

Refrigerant cycle:
Compressor pumps low pressure gas into Condensor.
Condensor coil rejcts heat which turns high pressure hot gas to high pressure liguid refrigerant.
High pressure liquid refrigerant is pumped from condensor to a metering device(orfice/expansion valve) which feeds the evaporator.
The metering device(orfice/expansion valve)causes a pressure drop which turns the high pressure liquid into gas. The change of state from liquid to gas absorbs heat causing the evaparator coil to cool.

Re: A/C Conversion help needed
 

Thanks Guys ...Thanks Big Kev-O ....Refrigerant cycle info helps, Your 1st sentence has me confused...... I had the Evaporator with orifice tube, hooked to the top of the condenser.... Line coming out of the condenser ( orifice tube removed ) went back to compressor..... I think I have the lines hooked up wrong. I think I will switch the lines and move the orifice tube to the condenser.

Re: A/C Conversion help needed
 

Generic AC hook up. First picture.
The blue line is the bottom hoses of the evaperator and on mine the bottom of the condensor. The tube is just inside the connection.:chevy:

https://encrypted-tbn1.gstatic.com/i...FsdS3jaVX_SCxw

My setup is as pictured. The connection where the bottom hoses connect out of the evaperator to the condensor is where my orfice is.Which way it's facing not sure, I did this several years ago and can't remember.:chevy:


http://67-72chevytrucks.com/gallery/...m/DSCF2645.JPG

Re: A/C Conversion help needed
 

Thanks Andy4639... I think the orifice tube can only be put in 1 way, the ( + ) part of the plastic is what you see and grab if you want to pull it out..( I hope that's correct ) what had me confused also the 1 in the condenser faces the other way......I'm drooling on your motor, ( Sorry )

Re: A/C Conversion help needed
 

CORRECTION, oops meant to say:
Typically the high side gas from the compressor goes into the top of the condensor and liquid comes out the bottom to the metering device(orifice)which feeds the EVAPORATOR.

Im at work and kept getting interupted, darn it how dare people bother me while im supposed to be workin.
Posted via Mobile Device

Re: A/C Conversion help needed
 

Thanks,
Yes correct!:chevy:

http://www.autoacsystems.com/fasttra...rificeTube.jpg

The motor is out of a 2003 2500 H/D with the 4l80e transmission. It's pretty much stock other than the S/S headers and ECU calibration.
This is how it looks today.:chevy:

http://67-72chevytrucks.com/gallery/...m/IMG_3602.JPG

Re: A/C Conversion help needed
 

The arrow on the orifice tube should read ( Here's your sign! )...Thanks. never saw that...Awesome Help..Thanks for the photo's and detailed explanations... .Should be getting it charged up in a couple days.

Re: A/C Conversion help needed
 

Good deal man!

Mine runs 40* cooler than outside temp.

I also closed off the cowl flapper vent to keep the AC circulating the cab air. No fresh air when running the AC in less I open the drivers side kick panel.
My passenger side kick panel I put back manually and leave it open all the time.
One more tip for you. On the heater hose I have a manual valve to insure the heater coil doesn't get any hot water flowing through it. If it has any hot water flowing while the AC is on you will not cool the cab down. The vacuum valves are good but I like to make sure.:chevy:

Re: A/C Conversion help needed
 

Thanks again I will work on the flapper, I already added a shut off for the heater core......BIG KEV-O Too funny, work does tend to get in the way of what is important...I will post the results next week......Ed

Re: A/C Conversion help needed
 

I hope you are running a stock cam ,,, those compressors put alot of strain on the engine ,, Ill never use one again ,, the sanden units are much easier on your engine ,, that said

check and check again alignment and belt tension

Re: A/C Conversion help needed
 

Thanks for the input ...Yep stock cam, Jegs crate 350 190 hp...Pretty frustrated, after the engine I had been saving for this project didn't have good compression. Jumped on the crate motor to keep the project going.... Should have looked harder for a newer upgrade....350 with Demon 650 carb doesn't seem very peppy. I have been thinking of going back to a Rochester 2bbl.

Re: A/C Conversion help needed
 

My original description was wrong should have said Low side, goes up... Same results today, my A/C guy put in about 1.5-1.6 lbs R134 the low side pressure instead of staying at 45 starts to creep up. didn't throw the belt but would have in a few minutes..I tried to switch orifice valve to the condenser but could not get it to seat correctly bottoms out before it's all the way in the tube, so orifice valve is in the bottom of the Evaporator.....My A/C guy suggested getting a different Condenser, I don't see how that would make a difference but I might do that. Any suggestions would be helpful....Thanks

Re: A/C Conversion help needed
 

The condenser may be a problem- those laminar-flow style ones are just about impossible to flush. I replace them on Fords and Benz systems- any debris from whatever blow-up or other unknown situation ends up there, and stays there- until it gets loosened up by a fresh load of oil and refrigerant and pressure to push it. If it's clogged up, it can play hell with pressures, not to mention adding crud to an otherwise pristine system.

Re: A/C Conversion help needed
 

I thought the condenser flushed out pretty good, blew air threw it, seemed to be ok.