A/C Conversion help needed

[notsolo]

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.

[MARKDTN]

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?

[notsolo]

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.

[Big Kev-O]

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.

[Big Kev-O]

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.

[notsolo]

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.

[Bigdav160]

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.

[Big Kev-O]

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.

[Big Kev-O]

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

[motorcritter]

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.

[notsolo]

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