Conservative A/C Restore?

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pjbanman
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Conservative A/C Restore?

Postby pjbanman » Wed Jul 08, 2020 7:04 pm

Hello,
My 15 year old son and I bought him a very used 1976 Monte Carlo that we have started working on together to do a possible conservative restore.
From underneath the hood to the interior and maybe paint some day. The car runs fine but it does not cool and realized the compressor belt is missing which I assume that the compressor might be out of commission. We decided after pulling the leaky original radiator that we need to inspect or replace many of the original mechanical parts under the hood, i.e. water pump, fuel pump, alternator, leaky power steering pump, etc. After removing the condensor, the a/c lines, getting into the heater box on the firewall and disassembling the evaporator and blower motor. From there moving inside and removing the air mixer (or whatever it is called) under the dash. This is what I found: the condensor in front of the radiator seems to be okay? I pressurized up go 60 PSI under water and did not find any leaks, I did the same on the evaporator and no leaks (not sure if this is recommended). I am sure the hoses probably need to replaced and o-rings to convert to R134a, I assume a new drier too? Where should I turn from there without spending a ton of money on a vintage air conversion kit?
Should I buy a rebuilt compressor or a new sanden compressor?
Can i use the original condensor?
Can I use the original evaporator?
I assume I should replace the lines?
Should I shell out $1500 for a conversion kit (which I really don't want to do)?
My goal would be to take it to a professional to get everything re-charged, we would like to do anything we can ourselves for the experience and to save money.
Thanks for the help! Phil
Al9
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Re: Conservative A/C Restore?

Postby Al9 » Thu Jul 09, 2020 3:10 am

I'd use the new Sanden compressor. Energy efficient design, and a better lubrication system compared to the sumpless A6 version and the R4.
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bohica2xo
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Re: Conservative A/C Restore?

Postby bohica2xo » Thu Jul 09, 2020 6:26 am

It depends on what kind of shape the VIR is in. They are rebuildable. Is this a restoration? Do you want to keep all of the OEM parts intact?

If the vehicle sat with a failed compressor, but all of the lines remained connected - the VIR may be just fine.

The heater core should be replaced since you have it out. The evaporator core should be ok, unless it is corroded on the exterior from road salt / leaves sitting in the evaporator box with it.

The condenser is a tube & fin unit. They are tough, and flushable. But they have been replaced in newer vehicles with more efficient designs that are parallel flow units. Upgrading to a new style condenser can cool better, but will require making new lines and some mounting fabrication.

There is no sanden compressor with enough displacement to replace the compressor in that system. Some cars had A6 compressors, others had the R4. Both have unique mounting brackets, and are not interchangeable. Do you know which compressor you have? Unless you plan to change all of the accessory drives and mounting brackets, it is probably best to stay with what you have.

Conversion kits are a last resort if the VIR is in bad shape. $1500 is about 10x too much for such a kit.

Refrigerant. The VIR has a POA valve inside of it. They can't be adjusted. So the best performance will be obtained by using R12 refrigerant. If you do not want to deal with keeping it R12, then converting the system to CCTXV is the next best thing. That would require some work and any 134a conversion will need an upgraded condenser.
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JohnHere
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Re: Conservative A/C Restore?

Postby JohnHere » Thu Jul 09, 2020 6:45 am

If you want to convert it, you'll need to remove the VIR unit because it won't work well with R-134a and replace it with a clutch-cycling accumulator kit. However, I think I'd keep it R-12 for which it was originally designed, rebuild the VIR (parts are available), replace the 44-year-old compressor, condenser, and hoses, and flush the rest. R-12 is still sold in the U. S., although costly, and will cool the best.
pjbanman
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Re: Conservative A/C Restore?

Postby pjbanman » Thu Jul 09, 2020 5:03 pm

Thanks for the comments, I might be over my head on this, I am not interested in leaving anything original, just looking for the best value without too many headaches. See attached pictures (that is if they are posted). I am pretty mechanical but I don't have much knowledge on auto air conditioning.
Thanks!
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bohica2xo
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Re: Conservative A/C Restore?

Postby bohica2xo » Thu Jul 09, 2020 7:18 pm

VIR with an A6. King of the hill in it's day.

You have some choices. First, what is the climate like where you live? Phoenix vs costal Oregon means different things to an A/C system. That system was built to handle the 118f in Death Valley as well as the 90f & 90% humidity in the southeast.
pjbanman
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Re: Conservative A/C Restore?

Postby pjbanman » Thu Jul 09, 2020 7:38 pm

Hello,
Our area is dry, generally low humidity year round, we do have 4 season here in the Texas Panhandle.
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bohica2xo
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Re: Conservative A/C Restore?

Postby bohica2xo » Thu Jul 09, 2020 10:27 pm

I only recall two seasons in Amarillo. Wishing it would warm up, then wishing it would cool down...

Honestly the weather here in Las Vegas is not far off 109 today, 97 right now at 10pm - and 6% humidity.

Ok. Best cooling would be keeping the A6, VIR & R12 refrigerant, adding a large parallel flow condenser. Complicated, and not the cheapest route.

Any other choice will also have you fitting an aftermarket condenser. The site sponsor - ACKITS.com has a good selection of aftermarket parallel flow condensers. Tim can help you with that.

Going to 134a and a CCOT conversion has a couple of options.

To start with the accumulator and fittings for the orifice tube should not be terribly expensive. I have seen them under $150 recently.

You will need new hoses for the new condenser, and the conversion. These are not hard to deal with - you will need a local hose shop to help you. You can get the fittings from them, install them & mock up the hose routing & lengths with a piece of plastic tube, a chunk of discarded garden hose etc. Once you have the lengths the hose shop can cut the proper hose from stock, and crimp the ends.

The big choice is the compressor. The A6 is a solid performer, but complicated and not cheap. It has an internal sump, an oil pump, and will basically run all day long. And that is a problem. It was not designed for cycling operation. If your car had an R4 I would stay with it - but your brackets are A6.

Now, anybody that knows me will flinch at this suggestion coming from my keyboard...

Use the aluminum A6 replacement compressor. Yes, it has a little less capacity. I complain about that all the time. BUT, if you use a BIG condenser, and a great fan - it can do the job. Not as well as the VIR / A6 / R12 system did - but it should keep you comfortable.

Fan. The OEM fan was a viscous clutch fan. With the OEM fan shroud installed, and a clutch in good shape it did the job. If your fan shroud is missing, and the fan clutch is worn out - it will not cool well at idle & low speeds around town. Don't be fooled by various aftermarket electric fan manufacturers - this car was designed for a powerful mechanical fan.

You can probably sell the VIR to someone doing a restoration - it is in good shape. Recovering the cost of the new condenser, perhaps more. Corvette owners looking for OEM stuff need that part.
Al9
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Re: Conservative A/C Restore?

Postby Al9 » Fri Jul 10, 2020 2:07 am

If i'm not mistaken the S6 is a Denso redesign. In that case the metal piston rings have been replaced with a polymer coating. So at least less friction and hence thinner oil (runs on PAG 46), which could also mean better heat exchange. 5 pistons so smoother rotation compared to the 3 piston A6.
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bohica2xo
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Re: Conservative A/C Restore?

Postby bohica2xo » Fri Jul 10, 2020 6:29 am

a19

Put the Sanden catalog down.

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