firemn131

Ok. 87 auto ..Car is running great and my daily driver now..The A/C components work and i put 2 cans of 134 in..It does supply some degreee of cooling, but not nearly as it should..

So, i can let it go as is or try to get the system to perform better..
What is my sequence of steps to start?

O rings
Evaporate
replace dryer.

I am assuming that the system doesnt leak...
So to refresh, where do i start.

I have never done any A/C work before..

Thnx..i do have the WSM..

joejoe

Was the system converted from r12? You did not say if you evacuated system before adding the 134. If air was in the system cooling will be affected. Also if system is overcharged it will not work as well.

To your question... replace the 'o' rings with the green or blue nitrile ones. Replace dryer and expansion valve. Make sure you are using a compatible oil for 134 and a good flush of the system is never a bad thing when changing from r12 to 134. When replacement is done pull a hard vacuum to remove any moisture from opening system, let stand and make sure vacuum holds. If it does then add freon.

My cars are still r12 so I do not know capacity for 134 (I believe you use a bit less) I have done both my 928's and 3 944's we have so ne need to be worried about work. It can take some time and care as you will be removing steel nuts from some aluminum tubing (mostly the front condensor for those rings) When charging I do so by weight and fill to what is called for by factory, I believe for the '86.5 is 43.2 oz. as it has the rear a/c also. I think most '87s are the same (not positive though) and you need to compensate from r12 to 134. Hope this helps some.

SteveG

It sounds like you are really operating on "guesstimate" If there is no leak, why does it need 2 cans, if indeed it did? That is a lot, if the system was just low. Search here, there have been many threads on this. I would start looking for oily residue at any connection, but the best way to find a leak is with dye. On a system that has been converted, which yours must have been, old hoses can leak very slowly because the 134 molecule is smaller; if all you need is one can/year, most people would go with that as opposed to the cost of replacing hoses, dryer and seals; I would start with getting pressure readings. I don't have the ambient temp graph at hand. I think it is in the manual.

Speedtoys

These are your Orings at the compressor...right now.



That's what they will look like. All other rings looked ok..but who knows, they're all new ones today.

Its not hard to replace all of the Orings in the system if you have basic mechanical skills. I was just shown how to do it, and it was embarrassingly easy.

Add all you want, but..you gotta do this.

The front expansion valve wasnt even hard to get out..didnt need a strap to pull on the lines, nothin.

But..there ya go.

Speedtoys

Which one is it...you added 2 -cans- or you assume that it doesnt leak?

It cant be both.

JHowell37

I'm not that far from you and I'm pretty well versed in 928 AC. I've got gauges and a vacuum pump. I've also got 20lbs of R-12 that I'm looking to get out of my hair. Let me know if you're interested in meeting up and I can take a look at it.

SteveG

He put 2 cans of 134 in it. How much flush do you have??

firemn131

Both ====2 cans and assuming no leak..

Thnx Howell for the offer..A busy couple weeks coming up..I will let ya know...

dprantl

- What was in the system before you added refrigerant? R12 or R134a or ???
- Does your car have rear A/C or not?
- If the system was completely empty, you didn't add enough
- Refrigerant systems generally do not lose refrigerant unless there is a leak. If you had to add 2 cans, there is a leak unless you or someone else fixed it and didn't recharge the system afterwards (unlikely).

Dan
'91 928GT S/C 475hp/460lb.ft

blown 87

Please do not put anything with sealer in it.

Speedtoys

And sometimes you have to search the cans carefully at the parts store for cans with JUST gas.

Just sayin...

griffiths

Briefly...

Remove refrigerant.
Replace all o-rings in system (HNBR).
Replace drier with R134a compatible (XH-7 or 9).
Depending upon if you have rear air, add 6 ounces of Ester oil.
Put on a good set of R134a charge port adapters. (the ones with their own schrader valves).
Inspect 2 hoses at compressor for signs of leakage and age.
Inspect expansion valves for oil spots (signs of leakage).
Inspect compressor body and behind pulley for oil (sign of leakage).
Evacuate, charge and test with virgin R134a (no sealants or additives), charge by P&T.
Sniff all joint connections, vents, components with electronic leak detector.

WallyP

Griff-

Do you suggest always charging by pressure and temp rather than by weight?

Speedtoys

..I found pressure/temp to be useless. Im blowing 40d by "good guess" weight on a partial system (in total capacity)

griffiths

Wally,

We always charge by P&T (pressures and temperatures relations) and Weight of refrigerant. Consider using both methods together alike a Balance Sheet:
1) All too often you can run into a situation where things throw you off course, such as either equipment problems or brain farts. For example, a high side analog gauge that is off by 50 psi because the indicator needle moved on its shaft. A leaky site glass gasket on a manifold gauge set that won't let you achieve a good vacuum. Worn service hose end rubber gaskets.
Weak batteries in refrigerant scale giving false weights. Forgetting you had 4 martinis the night before which somehow prevents you from remembering which is the low and which is the high side.
2) You can have "perfect world" low and high side pressures but an inadequate amount of refrigerant, so noting the actual weighted charge of refrigerant put in the vehicle would alert you to the issue; excessive air in the system. Alternatively, you put in the correct weighted charge, your high side is too high, P&T would alert you to the possibility of excessive air as well.
3) Properly evacuating and purging the system to remove all moisture (water does freeze in a vacuum) so the TEV does not become a victim; properly monitoring vacuum during evacuation is key.

So in brief summary, a P&T and Weight "Balance Sheet" makes the process easier.

Other things that help, naturally, is knowing the abilities of your equipment.
We use digital low side gauges as well as micron gauges to check our service (gauges, manifolds, hoses and vacuum pump) equipment before and during the processes; and check battery voltages before starting each job. Other helpful tools are P&T charts, Boiling (evaporation) Point of Water charts, electronic thermometers that are NIST traceable, electronic leak detectors, educational reference materials, documenting the process and results. We never use 12oz or 16oz small refrigerant cans, only virgin 30 pounders, and we weigh the 30 pounder before and after each service and note the date and value on the cylinder.


Griff