SharkFan

I wanted to know if anyone out there knows if it is possible to add rear A/C to my 81' 928 Euro.? If so, has anyone every done it or know how to do it ?

Thanks,

Dave

Tony

i think it can be done, but, im sure its a PITA and a bit $$$. My first car had single air and was so so in the heat here. My car now has dual AC and is much cooler to drive in around here now.

Thom1

Dave,

Fix what ya' got... it's cheaper ta' keep her. See below:

THOM’S A/C SERVICE ESSENTIALS:

RULES:
1. If you open the system: Replace the dryer. Vacuum the moisture out.
2. If you convert to R134A, flush the old oil & contaminants out. Change o-rings. Oil o-rings before installation.
3. If o-rings are ever exposed, replace them with new ones.

RECOMMENDATIONS:
1. VACUUM GREMLINS ARE…STRANGER THAN FICTION! Fix them all before you try anything else.
2. With inexpensive R12 compatible refrigerants available, it may not be so good to convert to R134A. However, people have obtained very good results in 928s with R134A. See REFRIGERANTS below.
3. If you open the system, flush it too. By now it may have 2 or 3 times over the normal volume of oil plus contaminants.
4. Have refrigerant filled by a pro. You can blow out a hose or compressor by filling with cans, and/or without the proper gauges and/or methodology.
5. Replenish the pulley driven fan clutch fluid - get it from Toyota - Thickest part number version is 08816-10001
6. Clean the condenser – looks like a front radiator. While you’re at it, clean the radiator.
7. Expansion valve(s) may need to be changed – especially after compressor failure. (Sorry, but I do not know how to diagnose bad expansion valves. I don’t know if you get a big gain from this when the originals were still good. Many people really like to replace these to do it right. If they are bad, the system will never work right. There are different types specific to different refrigerants.)
8. Old refrigerant hoses may leak. Many people really like to replace these to do it right. Some new compressors come with new hoses too.
9. Clean the front evaporator. This is accessed when the cockpit blower fan is removed. Leaves, bugs, hair, dirt, will accumulate here.
10. Install the 75C Radiator Fan Switch to engage the electric fan at lower temperatures.

FLUSH & FILL: To flush the system use professional equipment and/or: Disconnect hoses and remover dryer. Flush out the old components with a cleaning fluid, and proper equipment. (Do not use compressed air, since it puts moisture into the system, and can generate corrosive acid compounds. Incompatible oils or contaminants can ruin your compressor.) You should put oil into a new compressor, and turn it manually a few times before you turn on the A/C, and after flushing. Connect hoses, and vacuum out the system immediately after the flush. Do not expose the inlets of the new receiver/dryer and compressor to the atmosphere until you are ready to add oil and connect hoses.

ORIFICE TUBE: Replacement of the orifice tube and dryer are required for warranties on American compressors. There is no orifice tube on a 928. The dryer filters contaminants.

REFRIGERANTS:
If you have R12, stick with it, or for less expensive refills – R12A, Hot Shot or MP39 sound good as inexpensive, compatible refills. R134A conversion can reduce efficiency 8-12%.

MORE INFORMATION OR PARTS: The Big 3 can provide parts. I have found excellent prices and service at 928 Specialists (828) 766-9280. See the griffiths.com site for parts and info. See the link below for in depth discussions by people from whom I have derived some of my recommendations:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001183" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001183</a>
More vacuum and electrical troubleshooting:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=002171" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=002171</a>
See Greg Nichol’s site for center console and instrument pod removal procedures, as well as more climate control tips: <a href="http://www.nichols.nu/tips.htm" target="_blank">http://www.nichols.nu/tips.htm</a>

VACUUM GREMLINS ARE…STRANGER THAN FICTION! There are 5 climate control actuators on an 86 model with flimsy rubber diaphragms to go bad. I have replaced 4 now. The remainder of this document addresses some of the vacuum actuators.

ACTUATOR VACUUM HOSE COLORS, LOCATION OF ACTUATORS, HOW TO ACCESS INSTRUCTIONS
YELLOW - Footwell Flap, forward of center console behind climate control switchbox, pull back center console & remove right knee shelf & right carpeted cover below center console
GREEN - Defrost Flap, left footwell & forward of center console & forward of ignition switch, easier if you pull back center console & remove instrument pod – but not required. Remove left knee shelf & left carpeted cover
ORANGE - Center Outlet Comb Flap, lower right side of center heater vent, pull back center console & remove glove box & remove right knee shelf & right carpeted cover below center console
WHITE - Heater (hot water) Valve, beneath air filter box on right, remove air filter box
BLUE - Fresh Air/Recirculate/Flap, right footwell above recirculation grate, remove blower fan & right knee shelf & recirc. grate & fuse box wooden covers. Pull back fuse box.
BLACK – Source Hose no Actuator, X vacuum line at brake booster then goes to manifold behind stereo, open hood or remove left carpeted cover below center console

HEATER CONTROL VALVE: The A/C will never be cold with a defective heater control valve or vacuum leak at it’s adjoining actuator. The valve (under the air filter) will by default bleed hot water into the heater core unless all vacuum leaks on the dash side of the firewall (and engine compartment extension/heater control valve) are fixed. The valve can be defective even if vacuum is good. The valve can be installed 180degrees reversed. The white side of the valve goes toward the firewall side. (If you replace the valve, also replace the 3-inch long water hose connected to it.) See this link on Greg Nichol’s site for applicable vacuum testing procedures from Wally and company:
<a href="http://ourworld.compuserve.com/homepages/nichols/tip509.htm" target="_blank">http://ourworld.compuserve.com/homepages/nichols/tip509.htm</a>
RECIRCULATION FLAP ACTUATOR: On my car the vacuum test through the black test port line did not reveal this faulty actuator. You can feel the flap by putting your fingers through a 2-3 inch rectangular hole behind the glove box. You can easily push it up. If the flap does not rise up when the engine starts, with the A/C and Heater controls off, it probably has a leaking actuator. See Tony’s great pictorial write-up about the recirculation flap replacement.
<a href="http://members.rennlist.com/v1uhoh/air.htm" target="_blank">http://members.rennlist.com/v1uhoh/air.htm</a>
Tony’s Center Comb and Heater Valve Lock-downs: (Note: A properly working a/c system requires none of these, or any other non-original modifications.)
<a href="http://members.rennlist.com/v1uhoh/summer.htm" target="_blank">http://members.rennlist.com/v1uhoh/summer.htm</a>
Tony’s CENTER COMB ACTUATOR Replacement:
<a href="http://members.rennlist.com/v1uhoh/combflap.htm" target="_blank">http://members.rennlist.com/v1uhoh/combflap.htm</a>
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Tony

Hey Dave
How about getting together this week for a Brew. ??. Im off M T W..and should be tomorrow (sunday). Pick a spot in your part of town. Drop me a line <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

SharkFan

For starters let me say wow to thom, and thanks for that indepth reply, I really appreciate it and that will be the first thing I do to bring the A/C to like new condition. With one exception, I'm thinking about trying out the refrigirant "Dura-Cool" which is supposed to be alot cooler than 134a and almost as cool as r12. Other benefits are, no conversion needed as it will mix with either of the existing refrig.'s without draining the oil. Higher combustion point then the others and more efficiant then either than the others.

Thanks again Thom,

Dave

SharkFan

Hey Tony,

Thanks, for the reply and I apparently did not get your post in time to get with you this Sunday but I would definatly like to get together one day. Unfortunatly, right now I am trying to settle my main transportation problem. I have a 2000 Honda Civic that was stolen last week for the third time and is now in the shop. So, I have been out looking for an SUV to replace it as soon as it gets out of the shop. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" /> As far as the rear A/C goes the main reason that I was intrested in it is, I have a 1 year old daughter that would benefit from this greatly out here in this "Dry Heat" lol. By the way, I just wanted to compliment you on your website it has answered quite a few questions that I have had. I actually attempted to e-mail you from your site and it came back as undeliverable. If you get a chance, could you drop me an e-mail and that way i'll be have a good email add. for sure. I have a ton of questions and would like to get to know as many shark owners locally as I can, since this is the first time that I have owned a 928 and expect a long and adventurous restoration and a whole lot of upgrades and changes.

Thanks,

Dave
davecandi1@lvcm.com

Normy

Wow Thom...you must be an HVAC type. My uncle does that, and helps me out now and then with advice about my weak AC-

N

Thom1

Hi Normy,

How is you’re A/C doing? Have you replaced that heater valve yet?

Thanks for the Kudos. I am an engineer that just became too frustrated, and poor paying supposedly qualified mechanics to work on the 928. I ended up relying on people with experience on this list, and Big 3 experts to give me good advice. When I gain valuable experience and knowledge, I return the favor of advice. I write-up some documents that I have been calling essentials to solidify my conceptions, and provide concise data to help out others.

The A/C experts became one of the most ridiculous encounters of my life. The first European expert rebuilt my compressor, replaced the rear evaporator, then started poking around inside the dash. About $700 later the shop manager told me that this mechanic had never worked on a 928. So, I was paying for him to learn and troubleshoot the A/C.

Then there was the Porsche dealership mechanic. He diagnosed a bad interior temperature sensor. But, could not even find the part number. (I cleaned up the guts of that sensor later, and found no problems.)

Then was the group with a huge lot of classic cars. They replaced the compressor, hoses, and expansion valves. They insisted on converting over to R134A. I later found that they did not have R12 certification or equipment.

Next was a generic small shop. They put in another new compressor, removed 4-5 times the normal amount of oil from the system. Per my request, they flushed contaminants, R134A, etc., and converted back to R12. The lead guy really worked, and obtained optimum gauge readings. He was getting cold air out of the back, but not the front. He said that it must be a vacuum problem that was beyond his expertise.

That is when yours truly became the mechanic. I bought a vacuum pump, and replaced 2 actuators in the dash. I had replaced the heater valve earlier. I cleaned up heater control contacts while I had the dash removed.

It did OK for a while, between each iteration of repairs. However, this Spring it was just not really cold. I found that the plastic heater valve had worn out, even though the attached actuator still held vacuum. With that fixed, I found that the recirculation flap never closed. This was supposed to show up by vacuum diagnosis through the black line. I went back into the center console vacuum manifold and clipped the blue tube. Voila’ no vacuum to the actuator. With that fixed, I now have the coldest air ever.

I imagine that 90% of my expenses would have been avoided, if I checked for vacuum leaks at the black line and the center console first. Even the Porsche dealership mechanic did not check for vacuum problems – to my knowledge.

I did not start to rely on Rennlist that much until I started fixing it myself. I appreciate the tips, and varying points of view. When I think I can contribute, I offer suggestions. I ask a lot of questions too. Before I start a job, I get as many opinions as possible. I try to map out all the possible solutions before I start. Various people help with various problem diagnosis’s. It is up to me to filter that information. People usually provide methods for you to track down the problem. There are also WYAITs that I like to do when I have exposed an area. I appreciate what others have done to help me. I have been burned by “knowledgeable mechanics.” When I can, I give something back to the 928 community.
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