atb

Just got my manifold gauge set and vaccuum venturi pump from Harbor Freight. I've got my new Griffith's Keuhl compressor kit installed and am ready to vaccuum down the system and install the R134a. I haven't seen a definitive method on how to do this, even the manuals are somewhat lacking.

My assumption was that I would hook up the high side and low side lines, and then draw a vaccuum through the central yellow line on the manifold guage set. Unfortunately, the yellow line does not bolt up the to vaccuum pump because the fittings are different. Since I haven't been able to find a fitting to mate the two together, I wonder if maybe I'm not going about it correctly.

Thanks for any input.

Thom1

Hi Adam,

Interesting that you went down the path I was considering. Fortunately, I sealed and filled my old wagon’s a/c system. Therefore, I did not spend money I did not really have on a/c tools. The Harbor Freight guy told me that the $14 venturi pump only works for R-12. You may find that one of the 2 or 3 fittings for R-134a conversion fit the venturi pump and yellow hose fitting. The fittings should be in stock this time of year at most parts stores. Is there another ¼” quick coupling fitting for your home air compressor on the venturi pump?

Did you get the $65 manifold gage set?

Please let me know what you determine about the venturi pump fittings!!!

Here is an Adobe Acrobat file of instructions: http://www.mastercool.com/manual/form12.pdf
See evacuation procedures.

Thom1

Another thought or two,…

Have you replaced all o-rings & dryer, flushed system, and prepped compressor with proper oil? See my essentials document 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 that are brittle and incompatible with POE oil used with R-134a. 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. UPDATE: An expert opinion states that old refrigerant hoses have been sealed by the old oil. Therefore they do not leak. Many people really like to replace the hoses per the old school leakage opinion. Some new compressors come with new hoses too.
9. Clean the front evaporator. This is accessed when the cockpit blower fan is removed. In the middle below windshield wipers… 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. (Compressed air puts moisture into the system, and can generate corrosive acid compounds. The shade tree mechanic really needs to vacuum the moisture out with a pump like the pros after flushing. 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, Freeze 12, 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:
http://forums.rennlist.com/forums/ul...&f=14&t=001183
More vacuum and electrical troubleshooting:
http://forums.rennlist.com/forums/ul...&f=14&t=002171
See Greg Nichol’s site for center console and instrument pod removal procedures, as well as more climate control tips: http://www.nichols.nu/tips.htm

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.

Check A/C vacuum at the black diagnostic tube going through the firewall at the brake booster. There is a 4 female point X connector there. (However, the previous test did not reveal a recirculation flap actuator leak for me. So, if climate controls do not operate properly, go to the next step.) If vacuum does not hold, check the colored tubes coming off of the back of the vacuum console behind the ash tray in the center console. Remove the left carpeted panel below the center console. Snip each colored vacuum tube, and check vacuum by pumping down the end that goes toward the actuator. Use an inch of rubber hose to slide over and seal the snipped ends of each vacuum hose.

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
NOTE: Above sequence of colors is as located from right to left on center vacuum 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:
http://www.nichols.nu/tips.htm
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. http://members.rennlist.com/v1uhoh/air.htm
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.)
http://members.rennlist.com/v1uhoh/summer.htm

Tony’s CENTER COMB ACTUATOR Replacement:
http://members.rennlist.com/v1uhoh/combflap.htm

John Pirtle’s vacuum actuator, center console, heater valve, etc. pictorial procedures:
http://members.rennlist.com/pirtle/svc.html

ErnestSw

Adam,
Did you install the pop up rear wing from an 87 on your 88?

atb

Hi Thom,

My A/C has never worked in the 4 years that I've owned the car. Here in the Pac NW, A/C isn't that critical, especially since my shark isn't my daily driver.

I reviewed all the options, but decided to go with the 134a conversion. I went with the Griffiths kit because it was a complete kit. My shark somewhere along the line picked up a FoMoCo compressor, a hack job of a rear A/C bracket, and some other oddities. So the compressor definitely needed replacing, and I had seen some instances of clutch failure on the OEM compressor, so I decided to go with the Griffith's unit which uses a different kind of compressor clutch than stock.

Regarding the pump, that's great info regarding the fitting being an R12 fitting. Every hardware person I spoke to said they had never seen a fittng like the one on the pump. An R12 to R134a adapter should definitely do the trick, I'll let you know. The back of the pump had a female receptacle that took a standard 1/4" quick coupling for my air compressor.

I did get the $65 set, looks like pretty good quality.

Thanks for instructional PDF Tom, it definitely makes things easy.

atb

ErnestSw wrote:


I did. I'd been wanting a flip up wing ever since I first saw one on a local car a few years back. A local '87 was being parted out, so I get my chance to acquire one. Just one more thing that reminds me how cool the engineering is on these cars.

Thom1

Hi Adam,

I have heard good things about the Griffith’s stuff. The compressor should have come with instructions for priming it with oil. The flush is essential for a system that has been down so long. It may have metal flakes, etc. that can damage the new compressor. If this is a new r-134a conversion, you gotta’ get new o-rings. Always change driers when changing compressors.

Let us know how it goes with that venturi device. It sounded to me like it would pull down enough vacuum to be effective. Hope a conversion fitting works. I would think that the venturi fitting would fit the yellow hose female bolt hole spec for an R-12 hose. Did you buy a male to male ¼” air fitting for the compressor interface? My compressor and hose set has a male on one end, and female on the other of the typical hose. The male goes into the compressor side. Can you just go to a hardware store and get the male to male quick connect?


You can get more instructions from the www.mastercool.com site.

atb

Hi Thom,

I've heard good about Griffith's as well. The kit comes with barrier hoses, O-rings, receiver/dryer, and compressor. The compressor comes pre-filled with 6 oz. of ester oil, and the directions call for an additional 2 oz. to be added when filling the system.

On the compressor interface with the pump, yes I just got a mail 1/4" pipe thread/male quick-connect fitting and bolted it right in. My compressor line hooks right up to it.

Gretch

Adam, more pictures of the wing and tell us the story, in more detail. I had not known there was such a thing as a pop up wing.

atb

I'll snap a few and post them later. The folding wing was the wing that was originally designed for the 928, and came on the early '87 S4's.

I believe the design was to give better access to that portion of the rear glass under the wing for cleaning purposes. It was discontinued because apparently there were some early failures in the mechanism, and the mounts are expensive to replace. The fixed wing soon replaced it in production.

One interesting story that I haven't personally verified, but has been relayed by others, is that if the wing is left loose on its mounts, downforce will lock it into place at 130mph.

atb

Oops, meant to say the folding wing was originally designed for the S4, did not meant to implicate any OB's.

Dozman

The problem with buying the cheap vac's is that they DO NOT! pull a deep enough vacuum. The vac should pull down to 29.97 inches, and at least 500 microns. If the vac can not pull down to 500 microns, it will leave moisture in the system. Yes, the drier will absorb some of the moisture but not all of it. If you put refrigerant, moisture, oil, and heat together you get acid. Not a good thing for the interior of your suction and discharge lines, your evap and cond coils, yet alone the compressor. It can be eaten from the inside out.

Talk to your local small a/c shop and tell the tech you want to do the repairs, and how much will it cost on the side for him to vac it down, and recharge it.

atb

Appreciate the heads up Dozman, but I'm still going to give it shot. I've gotten this far, might as well see how much vaccuum it can pull.

Dozman

I think next year i will go to Sharks in the Mountain and see if a few people need their a/c's worked on... or at least trimmed out.

Thom1

Heh Adam,

How is it going? Did one of those conversion fittings fit the yellow hose and venturi pump? Is it blowing cold yet.