246 A/C Help

I used the complete classic auto air kit on my 308 which comes with a compressor. Well built, and works well, although I can't speak to long term reliability as I did not keep the car that long. (they make a 246 kit too)

 

What type of failure are you experiencing?
I replaced the odd york/tecumseh compressor back in the day when they were current technology but dont recall recurring failures with them.
Perhaps Synchro will comment as he has more experience in this application than I do.
I replaced my original with a York but haven't finished the project yet.

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Texas would be Omega Industries but Lonnie doesn't like to sell out of his region and will help you find a local to you should you need it.

Repeated failures of the compressor may be the Effect, not the Cause - let's look further into this before jumping ship. Can you please tell us more about the failure?

1) Have you located the leak?
Has your AC guy installed a "UV dye charge" to locate the leak and is the failure located, isolated and identified? Dye is cheap at $5 and tells you much. Suspects could be the compressor main seal, one of the backseat valves, 40 yr ol hoses or elsewhere, but why start changing parts unless you're sure what needs it?

2) Was the old oil removed? Are you getting compressor hydro-lock?
Rarely do A/C people take the time to remove the old oil when installing a compressor (hey, it is lengthy, messy and difficult), they usually just "let it ride"
So. if you have changed Three compressors that yields Four oil fills netting 50-60 ounces of oil running around your system when 12-16 oz is all you need.
This extra oil not only displaces volume that refrigerant can occupy but can slug a liquid through the compressor (and liquid does not compress that well)

3) Has your AC guy installed his manifold an gauges to measure the High and Low side pressures and what the values your system is producing?

On a side note
Dino A/C fill should be determined based on Condensor subcooling measurements of your AC system
Using R-134a in a system with R-12 pressure sensors restricts you cooling by 70 PSI at the high end where R-134a needs to operate and you get less cooling


Hoping to be helpful
This is not an ad for my ebay kit

Scott

 

As I recall the York style compressor has a wet sump and doesn't require oil mixed with refrigerant. Adding any amount of oil while recharging could cause a hydro lock and compressor failure.
Years ago one of the guys I worked with wasn't paying attention and despite my warning added liquid refrigerant into the low side on a Ford LTD...hydro locked the compressor, broke a connecting rod which the exited the side of the compressor. He never wanted to do any ac work after that.

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Glad to help if I can

Please ask them to install an A/C dye package when they charge the system. I'm guessing that they visually inspected for oil marks to conclude "Not finding air/oil leaks" and that is a good start but not exhaustive in the A/C industry. A very small leak anywhere along the refrigerant path will now be identified by dye when paired with a UV flashlight ($10 Amazon) . It seems odd to me that 32 year old hoses are not leaking and a 5 year old compressor is, aka the most expensive part in the system.


As a side comment, R-134a molecules are smaller than R-12 and the old 45 degree flare seals that R-12 systems used are not adequate for sealing R134a refrigerant.
You stated your system was converted to R-134a but I think I heard that might only be a compressor and refrigerant change, correct?
The remaining systems has 15 flare seals at hoses, driers, fittings, etc that all need to be replaced with HNBR O-Ring type Seals or the R-134a will escape.
Then again, A/C guys love repeat customers and charging $750 for a Compressor change is good for their bottom line


But you're probably noticing that you don't see these leaks or problems in modern cars with reliable A/C like Hondas or Toyotas or daily drivers, do you? They just work for years and years.
These ALL use HNBR O-rings at every junction

There are two pressure sensor switches in most A/C systems for safety
- Low Pressure: Stops the compressor for running endlessly (and its premature failure) when there is no refrigerant
- High Pressure: Safely stops the compressor when pressures get too high (usually due to a clogged TXV - Thermal Expansion Valve)

Different refrigerants have different properties.
R-12 High pressure switches cut off at 389psi, but R-134a needs higher pressures before it gets to its optimum cooling ability, so it has a cutoff at 454 psi.
If you place R-134a in a system with R-12 high pressure sensor switche it will cut the compressor at 389psi and the refrigerant is not working in its most efficient cooling range, so you get less in the cabin.


Scott

 

Here is an A/C R-134a retrofit made using the Sanden compressor.
From the angled fittings, esp over the steering rack, somebody has put some good thought into this during the trial fit, very nice.

EU 2500,00 is about $3k USD and you do not get an evaporator - that means you will use the OEM evaporator with its weak flare seals

https://www.autoepoca.it/?s=air+condition+1915

 

Later Dinos used the O-ring fittings. I wonder if they have two versions of their kit.

 

Cheaper stateside $1600, again, no Evaporator which means you are grafting old R-12 style seals into the system. I'll wager you will be lucky if a charge lasts a year. The aluminum pipes are intended to stick up by the spare tire carrier and will be seen in concours.
https://www.classicautoair.com/shop/1973-ferrari-dino-246-lhd-air-conditioning-system/

This is the second time you've stated that and it piques my interest as I thought those weren't available until R-134a days in the 1990s with HNBR O-Rings coming into play.
Have you seen several, do they use black butyl O-rings or Viton (neither is good for A/C) - do tell more please?

 

[This is the second time you've stated that and it piques my interest as I thought those weren't available until R-134a days in the 1990s with HNBR O-Rings coming into play.
Have you seen several, do they use black butyl O-rings or Viton (neither is good for A/C) - do tell more please?[/QUOTE]

The parts catalog shows two part numbers for all the freon lines. My 72GT had flared fittings and my 74 GTS has O-ring fittings. I think I have some spare NOS O-ring lines with the part number tags still in place. I will get a picture if I can find them.

 

Very cool - thank you for revealing these historical Dino A/C details. I find this stuff exciting !

I had assumed all Dino A/C condensors were the same as I had seen many like mine (is anything the same in Dinoland, ha!). 05072 also has the early style with the early Stub hose pickup points on the condensor, yet the radiator had the later style condensor pipe clamp on the passenger's side.

I conclude that 05702 was near the transition as Ferrari knew when they made 05702 that the radiator pipe clamp would be needed for the new style condensor yet Ferrari installed an early condensor.

My OEM condensor 05702 was originally just as seen here on 04502 recently coming to auction with a "shorty" condensor. Look at all that unused real estate that the condensor could be occupying on the "Shorty" where you can see the hose going to the passenger's side.

Keep in mind the Right radiator fan is the one activated by the A/C circuit yet the "Shorty" condensor barely extends into the path of the Right cooling fan


BTW, I'm putting some subcooling measurements together to show evidence that the condensor is the limit of the Dino A/C system's cooling ability, even with the new R-134a evaporator.


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This is a NOS O-ring hose on Ebay:

https://www.ebay.com/itm/Ferrari-246-Radiator-Pipe-320456/120897227634?hash=item1c26094b72:g:~msAAOxyJs5RcnEE