A/c

[Porsche 935]

When I bought my 84 Carrera, the A/C did not work. I put freon in and it lasted for 3 or 4 days. The previous owner paid someone to put a new condensor, evaporator, drier and denzo compressor in. I put the dye in and couldn't find the leak. I hooked a vacuum pump to it and it held good vacuum for 6 hours but when I add freon it is gone in a few days. Thinking it might be the compressor. What is the best compressor to install on this car?

[86 911 Targa]

Originally Posted by Porsche 935

When I bought my 84 Carrera, the A/C did not work. I put freon in and it lasted for 3 or 4 days. The previous owner paid someone to put a new condensor, evaporator, drier and denzo compressor in. I put the dye in and couldn't find the leak. I hooked a vacuum pump to it and it held good vacuum for 6 hours but when I add freon it is gone in a few days. Thinking it might be the compressor. What is the best compressor to install on this car?

You may want to use a leak tester.

Try Harbor Freight.

pm me as needed.

Best,

Gerry

[gregwils]

If it's leaking out of the compressor, then you should see it with dye. It can leak by slowly leaching through old hoses, but not in 3 or 4 days - more like months.

You can buy a new compressor, but not sure that anything will last longer. You are saying freon, we assume you mean R134.

[Porsche 935]

Yes 134a, gonna borrow my friends leak detector. There was a bit of an issue when trying to connect my gauges to the compressor, that's why I think it could be a problem with that port.

[Discseven]

My suggestion is not to throw any money into parts... yet. First sort out exactly how to connect and disconnect your gauges. No offense... but if used incorrectly, it's very easy to make the system appear faulty by flubbing the use of gauges or even ruining a Schrader valve---which from what you stated 935... is very possible. If you have o-ring sealed protector caps in good condition that screw into ports, and there's some charge in system, and if a Schrader is leaking... when you unscrew cap... you'll hear a psssst. Instead of a compressor, you'll be spending a few bucks on Schraders.

[Bob Kontak]

Originally Posted by Discseven

My suggestion is not to throw any money into parts... yet. First sort out exactly how to connect and disconnect your gauges. No offense... but if used incorrectly, it's very easy to make the system appear faulty by flubbing the use of gauges or even ruining a Schrader valve---which from what you stated 935... is very possible. If you have o-ring sealed protector caps in good condition that screw into ports, and there's some charge in system, and if a Schrader is leaking... when you unscrew cap... you'll hear a psssst. Instead of a compressor, you'll be spending a few bucks on Schraders.

+1.

Next time you drop $15+ for a 12oz can of freon that you know you are probably going to lose, think about a $100 30lb tank of R134 at advance auto. They are 125 but will sell for 100.

If your friend has a sniffer, bet he has gauges.

Sniff the shrader valves with caps off. I spray with carb cleaner and air blow them dry. Gets rid of residual refrigerant.

The HF sniffer is about $65. Your friend's should work fine.

Check and check again. The sniffers are finicky. False positives are common. Confirm leak point with the least sensitive setting.

A three day leak will register, no problem. Just gotta find it.

[kuehl]

If you put dye in the system and "can't see the leak", meaning you looked at the compressor, you looked at the engine deck lid above the clutch pulley (for the oily line of death underneath) every hose connection to each component:
compressor, deck lid condenser and front condenser, drier, expansion valve and evaporator outlet ..... if the dye you are using requires a black light, based on losing a full charge in 3-4 days..... you should have seen the leak or the leak is the evaporator in the smugglers box that you can't see inside.

An electronic leak detector of any value will show up a leak of this magnitude.

Original hoses can leak out a lot, it all depends upon their condition, and the more you use the system the more it leaks. A common leak in hoses hard to see is under the rear lift pad areas; its common for car lifts to crush the hoses under there, or sometimes its hoses at the drier; tire rub. But again, a black light with fluorescent dye will be easily seen.

If you can't see it then its time for another set eyes, either an experienced friend of simply pay an experienced tech to find the leaks for you (cheaper than putting in cans of refrigerant weekly).

[T77911S]

I found a leak in the left hose that runs from the rear to the front right in front of the rear wheel.
when I removed all my hoses I found another hose with a hole.

I had all my coils pressure tested and replaced all my hoses....still waiting to put them in

[kuehl]

In answer to your question in your initial post on 'best compressor' for 84-89 911, the Denso is the best choice.

Here is my suggestion if you are satisfied with the current AC performance when the system was working:
1) Tear down the compressor, inspect the bores, pistons and wobble plate,
if they look good and you don't find any grey colored matter or metal particles and refrigerant oil looks clean, get a compressor seal kit.
2) New barrier hoses, o-rings, drier and low high pressure switch.
3) You'll need to add between 4-5 oz of refrigerant oil for the losses from the leak and replacing items.
4) Evacuate, charge, test and sniff.

Enjoy the rest of the driving season.

[Porsche 935]

Thanks all, yes my main question was about the compressor if or when I need one. I am a licensed A/C mechanic so I know how to hook up the gauges properly. I have gauges and a vacuum pump but no longer own a recovery machine or leak detector. I will find the leak, component replacement is easy. Just want the best on the market for the Florida weather.

[GH85Carrera]

With the system at 100% stock and working perfectly as it was delivered new with R-12 the system is OK for most conditions, but inadequate if it gets HOS and you are not moving. With R-134 it is a little less adequate but not a lot.

For Florida it will struggle.

You can throw some bucks and work at it and replace the rubber hoses. Add one or more condensers and the routine parts like the o-rings and receiver-dryer and get good results for any and all hot days in Florida. I can even make myself COLD on a high 90s day in full sun.

[Bob Kontak]

Originally Posted by Porsche 935

I am a licensed A/C mechanic so I know how to hook up the gauges properly.

Good info. Until we know it's best to assume you are just starting out.

As a side note, the air is pulled from the floor boards into the evaporator and then upwards.

If you take the board and electrical thingie off (passenger side) you can check out and remove the fuzz on the bottom of the evaporator. Tight but doable. Might help.

[Porsche 935]

Finally got a electronic leak detector. Hooked up my gauges. System still has 50 psi, so leak must not be as bad as thought. I only had a partial can of freon, so installed it. So far, have not found leak. Did check schrader valves at compressor. High side looks like normal schrader valve. Low side does not look right and the cap will not thread on. Is this port replaceable ? Looks like it can be unthreaded, but it did not show a leak. Going to get freon and bring system up to operating pressure and try and find leak. Evidently it only leaks the most at full pressure.

[T77911S]

you don't need much in there to find the leak.
turn on the fan and sniff the vents
also spray soapy water on everything.
open smugglers box and sniff in there.
even though my left side hose had a protective foam around it I still had a leak. sniffed it coming out of the foam padding.

post a pic of connections

my latest leak is the rear condenser.
I put in 350 psi of nitrogen and it dropped pretty fast then slowed to 150 as of Monday.
leak seemed pretty bad based on bubbles and how fast it dropped.

need a rear cond.....

[Porsche 935]

Topped off A/C this weekend, so far could not find leak. Put mirror by low side connection on compressor. Say piece of metal in there. Blew out with air, tried to tighten schrader valve but tool will not reach and cap would not go on. Found a threaded insert in the valve, managed to get it out. This is also why cap would not go on. Is valve available for low side?

[kuehl]

If the car has R12 service ports on the manifolds (R12 service ports have threads on the outside), 'usually' you can remove the schrader valve with a common tire tool. If the car was converted to R134a and the service ports have no threads on the outside, their schrader valves tend to be deeper in the service port and you may have to visit the local auto parts store to get a AC schrader valve tool.

Although schrader valves all look the same some are unique and may not be interchangeable between service ports.

Does this compressor on your car have R12 service ports or R134a service ports?

[Porsche 935]

It has 134a valve. It was unusual that there were no threads on the inside for the cap to screw on. The piece I removed from the inside of the valve connection was smooth on the inside with fine threads on the outside, like someone tapped it to repair the or replace the schrader valve. Will the whole valve connection uncrew from the compressor for replacement ? the cap goes on now but not sure if it fits the way it is suppose to since it was probably damaged from whomever tried to put it inside a non threaded valve.

[kuehl]

I'd put on a complete new set of *R134a service port adapters that have their own integral schrader valve (as opposed to cheaper adapters that simply have a pin that pushes down to the old R12 schrader valve).

When you put on *these service port adapters be sure to remove the old R12 schrader valves from their ports before you screw them over the R12 service ports

[Porsche 935]

The denso compressor was installed new about 9 years ago. It does not look like an adapter but I guess anything is possible. All receipts show 134a as always being in the system. It had new condensor and drier put in about 4 years ago with fans for the rear condensor. Also had new evaporator installed when compressor was replaced. Is that whole service port block replaceable or it's components?

[kuehl]

Here is a pic of a 1984-1989 911 with a Denso compressor and R134a service port adapters. Red is high side and Blue is low side.