82Porsche928

My ac isn't working either. If you guys would message me when you are going to tackle this, I just like watching and learning.

VegasGnome

Brighton, The more the merrier! I am standing by to hear from Hayden. Being retired I am available most any day/time. I will let you know when I hear from Hayden.

HaydenM1974

Been super busy with work...found out that they loan the gauges and pump at Autozone for free with deposit....may go that route with my lack of any time off of work. I am thinking of trying the Interdynamics retrofit kit that uses the Ester oil mixed with refrigerant. Their Q and A on the website is very informative and convincing and the product has very high reviews on Amazon. That all depends on how the vacuuming of the system goes.

SeanR

This guy speaks the truth.

dr bob

Vernon--

Lots of info available with search. Lots available from the Porsche pubs, including all the o-rings needed, hoses needed for complete reseal. There are two principle hoses and a couple smaller ones, more if you have rear air.

It sounds like you aren't familiar with A/C systems though. From that I suggest you find professional service help. There's nothing exotic about the AC system or its components in the 928. So finding someone capable of working on it shouldn't be too bag a challenge. Finding someone who is willing to work on it may be tougher.

The low pressure port is inside the right (looking from the rear of the car, right is right) fender wall, forward of the crossbrace but behind the radiator, about 5" below the top of the fender.

The high-pressure port is on the high-pressure piping at the condenser and receiver/drier, right side forward of the radiator/condenser and near the top.

You can get the factory workshop manuals on CD from Roger at 928'srus, one of our sponsors. The CD compilation includes the Porsche AC service manual, and also includes a tech specs and parts catalog tthat has diagrams of the AC system, with locations of all the o-rings, hoses. etc. including sizes and Porsche part numbers. The o-rings are common AC o-ring sizes so they can be sourced locally, or call obne of our vendors and get a care package made up with all the ones you need. You can buy new barrier hoses or have yours rebuilt locally with new rubber sections too.

There's more to the total servicing than just replacing parts. This is clean-room work with no contamination with dirt/crud/debris/moisture. You need a serious vacuum pump, gauge and mannifold set, a good scale for getting the right amount of refrigerant, system oil for compressor lubrication, refrigerant (NOT the little cans...), and 3.81 gallons of patience and careful work.

Do some searching on this site. Then start a thread aboiut your situationa and you'll see plenty of support information.

dr bob

Retrofit for R-134a, and repairing/resealing for R-12 aren't too different. For either, you need to fix the leaks, drain and rfill the compressor with the correct oil, new hoses, new drier, --AT MINIMUM--. Anything less is a band-aid and IMHO a waste of time and resources. For the retrofit part, you want to use the Poly Olester compressor oil only after all the old oil is removed from the compressor. The oil will chew through the original o-rings so be sure to replace them ALL. The kit instuctions make it sound like you just change this fitting, pour this oil in, add refrigerant and you're good to go. It does sort of work like that, after you fix all the leaks (hoses and o-rings), clean all the old oil out (easy while the compressor is out and un-plumbed for the new seal and o-rings), drier replaced, system pressurized with dry nitrogen and leak-tested, then evacuated overnight. At that point, it's ready to get the new oil sucked in if you didn't fill the compressor while it was out. And add the new refrigerant.

The Forgotten On

^^ This, I was turned away from multiple shops because they said "we will not work on these cars" So I did all the hard work and had them fill it.

It is not too bad to assemble the system yourself, the tricky part is filling it to the proper amount. I left that to the professionals as I am sure you might.

griffiths

After recovering the old refrigerant, a vacuum is used for 2 purposes:

1) To remove all non condensible gases (air) which can cause
poor system (refrigerant) performance. Residual non condensible gases mixed with refrigerant reduce the needed refrigerant capacity and can cause high system pressures.

2) To remove all moisture. Moisture (water) in the system can break down refrigerant oils, create acids that etch metal components, and freeze up in the system, such as at the expansion valve.

The only benefit a vacuum plays in the process of evacuating and charging a system in terms of locating a leak is for a "gross" leak check. A gross leak check is performed after the vacuum pump has run a specified period of time and to a specified level of pressure. Example, you pull a vacuum for 1 hour down to -30 inHg. You close the gauge valves, turn off the pump, and wait 1/2 hour to see if the pressure rises significantly. A significant rise in pressure would tell you that you have a serious leak; hence you would not waste your time continuing with the complete charging process. The reason -30 inHg won't expose all the leaks is because it is only equivalent to -14.7psi. When the system is operating the high side can be as great in range of 180 to 340 psi (the higher the pressure the more obvious the leak will be).

82Porsche928

Someone just pm me if we are going to do this. I am not working now, as my business in being constructed as we speak. So if you guys decide to do that, I would be more than happy to help in any way I can, I just like learning. I can provide the beer...

HaydenM1974

Well being impatient as I am I went to Autozone and rented for free the manifold gauges and vacuum pump. I followed a good video on Youtube and used the interdynamics EZ Chill retrofit kit.
The air now blows cold. It's not going to give you frostbite but nevertheless it is working. I will report further after the temp outside gets up to 90.

dr bob

Did you fix the leaks, and use o-rings that will survive with the polyolester oil? Replace the expansion valve with one intended for R-134a characteristics? If not, you will soon.

HaydenM1974

Well so far so good....The AC is still cold and no leaks thus far. I added UV dye when charging it. The only issue I have so far is the heater valve may be letting small amounts of hot coolant into the heater core because when I reach into the center vent I can feel the warm air coming off of the heater core which is mixing with the otherwise cold air coming off of the AC evaporator. Will be ordering either a heater valve or a manual shutoff as I won't have any need for heat in the next seven months.

griffiths

Invaluable Shark Tips:

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