I am planning on swapping my 76 a/c to 134 and had a few questions and request for advice.

-got a working A6 compressor, condenser and evap. I plan to take it all apart, flush with mineral spirits and replace the VIR (valves in the receiver) with a new one. Can you use a new VIR which was maybe designed for R12 with 134? will it work good enough? Apparently the aluminum colored accumulator was on later years. Or should I retro fit?

-I can not find out for sure if the original 76 a/c system had the evaporator refrigerant orifice (white plastic piece that inserts into the evap inlet pipe). Does the 76 VIR design have this white plastic orifice?

Any and all advice from a/c experts is welcome

Much thanks!

 

Hi 20 Mercury,

I have the same set up as you for my 1976. The reciever drier I have is gold in colour. I have bought a dessicant kit from Napa to adapt to R134. I have upgraded to the new 'gasket and green o-ring kit'. I have a rebuilt A6 compressor with new hoses. I am looking to flush and place a vacuum test for the system and then recharge with R134. There are many papers on the cooling capacity of R134 and the adjustment of the pressure to achieve efficiency.

Can you tell me the reason to change out the reciever drier. I thought about that as well but found no vendor that would state it was compatible with R134 hence me overhauling the unit. I would appreciate if you could identify the vendor for your drier. The up grade dessicant kit was about $25.00 dollars.

Dano,

 

Here is the link to an Autozone VIR
http://www.autozone.com/autozone/par...156463_0_7620_
This one is $85, Corvette America is $188 for I think the same part.

Still learning about a/c, but I thought it was difficult to flush out the VIR. On the other hand, I thought I could get a good flush on the evap, cond, and lines. Also, I got a new compressor hose/muffler.

I thought you were supposed to adjust the POA valve for 134? Can you adjust the 2 valves in a VIR?

This is a VIR from Autozone, and I assume is for R12. I think the R12 VIR will work but probably not as well as one designed for 134?

The other better route may be to go with a later silver accumulator and other parts, but I do not know how much adapters you would need.

I have a number of links for a/c stuff, but I do not think any of them discusses VIR design. Please let me know if you want the links and we can trade.

 

Thanks for the info. I have read but cant locate now that some adjustment can be made by using an Allen wrench in the valve at one of the ports, I wish I knew.

I was not able to get an exact answer about why a R12 VIR drier can't be used. I wonder if it is about the type of dessicant in the unit as the upgrade kit for 134A is type XH-7. If that was the case, could you by a new unit and replace the dessicant?


Dano,

 

there is a freon i just saw at carlisle called enviro safe. requires no conversion of a factory system. the guy told me it is colder than other freons. if i remeber right, it was only about $35 or so for the freon and oil charge. i was going to do the 134 conversion on my '76, but will do this now. also, there was a fitting that he recommended being changed to show that it was converted but is not mandatory. he said you can just put the sticker on your car showing the new freon in it.

 

The guy lied to you.
Here's a start
http://www.epa.gov/ozone/title6/609/wantknow.html

 

I have a 76 that I converted from R-12 to R-134. I changed all hoses and o-rings, and installed VIR eliminator kit. The original VIR was calibrated for a certain pressure drop using R-12, the VIR eliminator kit is calibrated for R-134 or R-12.

I bought most of my Parts from Ecklers. The low pressure hose from the compressor has a crimped fitting that wasn't oriented correctly. I had to cut it off and order a new fitting from NAPA. I drove my car to NAPA and got the correct hose end alignment in their parking lot. Took the hose inside and let them crimp it for me.

The VIR eliminator kit came with a pressure cutoff switch that I installed to make the compressor cycle on and off. My 76 has the low hp L48 engine. When I turn on my AC it drops the RPM's about 600 so I added a solenoid to help with the idle. I was recently told (after I have installed everything), that I didn't need to install the cutoff switches or the VIR eliminator kit. I wish I would have tried it without.

I am no AC expert. I read up on AC Forum. They have a ton of good info.

My AC blows good and cold, but cycles too much. My fan doesn't blow very hard. However, I just replaced all the seals in the AC/Heater box on my 1971 vette. It now blows very hard. So I am going to do replace the seals in the 76 this winter.

Good luck

Roger

 

http://autorefrigerants.com/co00033.htm

I called this company and they walked me through what was need to be done. I purchased a vacuum pump at Harbor Freight for around $65.00 and although it was a piece of sh$%, it did the job. The system works better now than it did when new. Total cost around $135.00 including the pump.

 

Thanks for the info and advice!

 

yeah, that is what i saw at carlisle. did you have to do any mods?

 

no mods at all, that was the best part

 

Just re built my 76. Advise u to purchase the VIR eliminator kit from Ecklers, zip corvette,or any other auto supplier ,about 180.00 $$.purchase a ac flush aerosol presureized can $20.00 at your auto store if you flush with anything use alochol.and hook up to a shop vac it will suck and blow to clean the system. Then replace the o rings with green rings use ester oil on them.make sure to vacum n at least 3 hours to remove the moisture and vapors.also change the compressor oil use the ester oil 8 ozs.the old steel vir is history now,and the plastic detail u questioned about isn’t in your 76.lts a jobless cut a square about16x16 in the right fender well to gain access to the vir and ac equipment it’s a cut just below the plastic radiator over flo tank.Mineral spirits is a no no.,and the valves in the old vir will cost about $250-300 I checked. Good luck.

 

They tell that the valves (2) of them in the origional vir collect rust from the steel vir,and the end result are sticky valves.the new vir eliminator kit is made of aluminum. Classic auto air sells a kit pt#15-211 this is the kit I used for my 76,I believe on vette is all origional numbers all match.you also need to replace All o- rings and change the compressor oil to ester oil and oil the new Green color rings. The A 6 compressor will accept the newer 134a Freon but u must do all the mentioned changes.You will find it eeasier to cut a 16x16 square in th rt fender well just below the coolant overflow tank.,remove the rt tire .Its a job to say the least.

 

Yes u need to adjthe poa switch for 134a,contact Classic auto air,they are out of Florida.their vir eliminator kit is all aluminum and complete with good instructions,remember this isn’t for a beginner,it’s a retro fit u need to understand the ac principle.

 

The poa switch,valve need to have a shunt wire across the 2 terminals there is a screw in the center that needs to be turned ccw about 3/4 of a turn for the 134a Freon pressure (its a clutch operating switch) The shunt wire allows the compressor to operate while the adjustment is made then remove the temporary shunt and replace the origional new wire hook up.