1986 3.2 AC 134A Capacity

[PandA]

Howdy!

My wife is hot. Therefore I am fixing the AC on my 1986 911. Replaced all o-rings, front fan, compressor, drier, expansion valves, etc.

While the Bently manual has the oil capacity for the system on almost every page of the AC section, I cannot seem to find the refrigerant capacity. Newer cars have that on a sticker on the car. I am not finding mine.

Also, (on every other AC system I have ever seen) there is at least a low pressure cutoff switch. But Porsche doses not have this?? I remember Ford was having an issues with high low side pressures for a while and the solution was to include a pressure switch that would cut off compressor (or not let it turn on) if pressures are too high. We have none of these??

Hope everyone is having an amazing Sunday!

Andrews

[Canada Kev]

I seem to recall something like 47 oz of R12.

And no hi/low pressure switch. Check http://griffiths.com for stuff you might need or want for your AC system.

[86 911 Targa]

Originally Posted by PandA

Howdy!

My wife is hot. Therefore I am fixing the AC on my 1986 911. Replaced all o-rings, front fan, compressor, drier, expansion valves, etc.

While the Bently manual has the oil capacity for the system on almost every page of the AC section, I cannot seem to find the refrigerant capacity. Newer cars have that on a sticker on the car. I am not finding mine.

Also, (on every other AC system I have ever seen) there is at least a low pressure cutoff switch. But Porsche doses not have this?? I remember Ford was having an issues with high low side pressures for a while and the solution was to include a pressure switch that would cut off compressor (or not let it turn on) if pressures are too high. We have none of these??

Hope everyone is having an amazing Sunday!

Andrews

A high/low pressure switch is available from

These folks.

https://nostalgicac.com/

I have one on our '86.

Best,

Gerry

[86 911 Targa]

Originally Posted by Canada Kev

I seem to recall something like 47 oz of R12.

And no hi/low pressure switch. Check http://griffiths.com for stuff you might need or want for your AC system.

That's right.

But for R-134 I think it is 80% of the R-12 value.

Best,

Gerry

[Canada Kev]

Yeah, it's about 75-80 percent of the R12 amount, but as I understand, it's not a hard and fast ratio. Best to start lower and work up as the pressures and temps get to the most efficient level.

I hope the OP replaced the lines with barrier hoses, as well, or he's gonna be replacing the refrigerant pretty regularly.

[Discseven]

Originally Posted by PandA

I cannot seem to find the refrigerant capacity.

Andrews... suggest forgetting about capacity as your Porsche may have an unusual hose config (may not.) Go by temp>pressure. Griffiths has a Porsche temp-to-pressure reference chart. Not sure if that info is published on his website. If not, ask him for it. Idea is: optimal refrigerant charge is based on charging AC system to a specific pressure based on current ambient temperature (and humidity if you want to take it a step further.)

Edit--thought I had corrected this post earlier but apparently not... Griffiths has proprietary temp>pressure calculation that is provided with purchases. What purchases I do not know. My bad for incorrectly shooting mouth off. Appologies.

.

[PandA]

Thanks for all the replies!

Does not look like Griffith's publishes much of anything. (Like prices) I'll give him a call for that Pressure / Temperature Chart.

Thanks again!
Andrew

[T77911S]

pressure "chart" is on your gauges or you can get one off the internet.

he has prices on his site.
he is a great guy and a great help around here and hate to say anything bad but I am not a fan of how his site is laid out.

Porsche uses the thermostat in place of a low pressure gauge. not a good idea. my low side runs around 15-20. just make sure it does not go into a vacuum. rev the engine to verify this.

have you checked for leaks?
I ended up just replacing all hoses and all 3 coils.

[kuehl]

Start with 36 oz weight of R134a.
In a perfect evacuation you are usually around 39-40 oz R134a for a 47 oz R12 system.