911-TOUR

What can the Porsche System Tester 2 tell me about the system, exactly? I'm guessing it'll tell me if the ballast resistors are toast, or if the CCU is fried, but beyond that what would I gain by having the codes read out?

If anyone is wondering, the air is blowing strong, but hot & humid in the Houston heat, even with the AC on MAX (top snowflake). Haven't started the diagnosis yet (from the AC diagnosis thread), but am guessing:

In order of likelihood:
(a) Toasted Ballast resistor
(b) Toasted R14 relay
(c) Clogged/Damaged Condenser Fan
(d) No charge in system (it is 16 years old, after all)
(e) Leaky hose
(f) Damaged Compressor

Only mitigating circumstance is that I replaced the belts immediately prior to AC failure (yes I checked the green wire - connected, and reading 12V to ground at the terminal). Not sure how replacing the belts could have blown the AC ?

TIA,

sean

95C4VanIsle

I am far from a DIY guy but I had the same problem when the servo motor in the driver side footwell failed. It controls some flap that will either allow, or stop, hot air from entering the cabin. If the servo fails the flap will remain open (or closed) and allow only hot air throuth the vents, regardless of the air conditioner temperature setting. When this occurred with my car the vents were blowing out hot air throuth the center vents and one side vent. The vent on the passenger side would blow air more like the ambient temperature outside the car. This may not help you as the temp's in Houston are probably pretty hot right now. A mechanic replaced the part and all is fine now.

It is something to check out at least. I can't help you with the other diagnostic issues.

ToreB

Hi there Sean.
Your guessing is good, but not entirely correct. You most probably have a (small) leak in the A/C system. Recharge the refrigerant and I think you will be OK. This procedure often include checking for leaks, and maybe inserting some dye for spotting them afterwards.
The compressor clutch will not engage with too low pressure/low refrigerant level. Therefore, rule out any electric fault until refill has been done.
Your post indicate that you are not getting HOT air from the engine, but normal hot and humid outside air. It is therefore unlikely you have one or two defective (stuck) hot air mix flaps. This is a common fault though.
A defective ballast resistor will stop the condensor fan at low speed and the CCU will start high speed instead. This will not affect cooling. But, resistor should be be changed to avoid long term damage due to the chance of excess pressure.

Cheers,
Tore

911-TOUR

Anyone have the procedure / part nos for a recharge ?

911-TOUR

Well, verdict is in. Had the car out to the shop over lunch today. Checked the codes, recharged, and walked through with the Leak D'Tector. Drum roll please.....

....and the winner is: leak in the evaporator core. No codes, and a distinct R134a leak detected in the upper dash vents after the recharge with only the fan blower on (R134a leaking from the evaporator is immediately pulled through vents with the fan blower on).

Ugh. Time to start digging through the DIY archives. Looks to me like the car is essentially built to make the evaporator core hard to access ;-)

sean

ToreB

Welcome to the evap leak club. Here's an DIY:
http://p-car.com/diy/ac/
Good luck, it's a big job. I got my mech to do this for me with very good results.
Cheers,
Tore

TMc993

I clicked on the DIY link and when I saw the photo of the tools needed it may me taste a little vomit in my throat...You know when you see enough tools to cover a blanket and they are all simple hand tools that it ain't gonna be pretty...I know I need this job done on my car and I also know that when it is done Alan and his crew at German Car Repair in Atlanta will be doing it...I just don't have the stomach for that kind of work anymore.

911-TOUR

Awe c'mon...doesn't look all that bad - mostly just time-consuming ;-)

tchubacha

Or you could have seen it in person. What I've been up to on and off since Friday. Now putting it back together is going to be the "fun" part.

tchubacha

http://www.flickr.com/photos/23948407@N04/4850330136/

911-TOUR

Hi Tchubacha,

Yep...that's what I'm expecting...looks like when I had to rewire the dash 'cause the PO decided to have an aftermarket radio installed and the installer quietly "cut into" the wiring harness. I did that work 9 years ago...I was more flexible then ;-)

My biggest concern is where to find a high quality vacuum pump and manifold gauges. I don't want to buy them (good ones are $300/each) for only one use - and I'm not about to reassemble things before I've checked for good vacuum. What are you using and where did you get them?

Also, what evaporator did you go with ?

sean

tchubacha

I went with the Griffiths evap and valve. I have a 6cfm robbinair vacuum pump and gauges/refrigerant from a company in Magnolia called coolgas. Seems to work fine and delivery is quick. You are welcome to borrow whatever I have.

911-TOUR

Wow. Thank you for the offer! I just may take you up on that - I'm planning to tackle this later this fall. Is this a great place or what?

I'm leaning towards the Griffiths evap & valve as well. Seems to be the most recommended on both the 964 and 993 boards.

At least it's not a boxster/996. If you think changing the evaporator on our cars is a mess...

cheers,

sean

JPS

Diagnosing an AC issue...if it looks like evap no way I'll be tackling this...holy cow.

Paul M

I also have this task to look forward to in my near future, but would also need to borrow the vacuum pump and gauges from somewhere...