alabbasi

I'm trying to wake this car up and make it road worthy. Given that I live in Texas, this means getting the a/c working

I charged with R12 and the a/c is mediocre. But when going down the road, it starts to blow warm.

Could it be the expansion valve? If so, is it easy to get to?

The other question that I have is around the alarm. How can I disable it? I'm always fearful of alarms causing battery drain.

Last question: What's the switch under the hood for (the one that is activated when the hood is closed shut.

Thanks

MainePorsche

If it's mediocre, but gets warmer when driving then you are blowing hot air heated by the coolant fluid. Your heater valve/vacuum to it/vacuum to your hvac system/vacuum within your hvac system...
See Wally's write up under repairs and tips - https://www.928gt.com/default5.htm.

The one by the light bulb which is turned on when your headlight switch is on and the hood is opened...

alabbasi

Thanks, I'll take a look at the HVAC guide.
I apologize, I still don't understand the purpose of the switch under the hood.

Thanks

MainePorsche

If your hood is open and your headlight switch is on, the engine bay light should be on. I believe the switch 'un'-grounds the bulb when the hood is closed and the headlight switch on to keep this light off.

alabbasi

Thank you. Any idea on how to disable the alarm?

Thanks

Al

MainePorsche

Al,
Sorry, I am not well versed in the factory alarm system. I've thoroughly removed my PO's piece of junk, and wired my own. If you have Workshop Manuals give a look. If you don't, here is a link to them. Also Search the Forum.
Craig

http://www.2010.cannell.co.uk/manual...s_porsche.html

alabbasi

Craig, the manuals will help. Thanks again.

marinesniper0318

I had the same problem, vacuum hoses and a new compressor were needed, my certified 928 guy also found a fuel leak (thank god he saw it) and he resolved some other annoying issues...all for only 2k, to date I have spent almost exactly on repairs as my 1988s4 cost me to buy...

But I love her so...; )

Sniper

FredR

The switch under the hood is also a safety interlock that prevents the fans form running when the bonnet is open.

The a/c system on older German cars are generally known to be problemmatical and/or weak and the 928 is limited by the size of its condensor and on the S4 auto models more so becuase they have a transmission cooler that leaves the condensor smaller than on a manual transmission model. Add to that the fact that you are driving around in a greenhouse and it is not hard to see why the a/c system is challenged.

Having said that, if you can get everything spot on it can be made to work in relatively high ambient temps [ask me how I know]. Wally has an excellent wrtie up on this. The age related weak spots are the compressor seals [both dynamic and static seals], the expansion valve[s] and the joint rings [earlier models should have the later spec seal rings fitted- one is black the newer ones are green if my memory serves me correctly]. If your evaporator is the leak path then you are in for an outhouse full of fun if you want to fix it. The stock compressor is quite a good unit when working correctly.

The expansion valve[s] is easy to get at although they can be a bugger to release if the small allen head bolts round off.

Heat rejection film is also very helpful. With this fitted the car cools down much quicker if it is heat soaked. There is also the question of ensuring the surfaces of both the condensor and the evaporator are clean. The condensor is relatively. i beleive there ar eprorietary systems that can help clean the evaporator in-situ but I have no experience of them [yet].

I would not touch the alarm system unless you have good reason to do so. The 928 is infamous for bleeding current to earth but in my epxerience it has nothing to do with the alarm system, usually faulty relays or crumbling wire insulation.

MainePorsche

Thanks Fred. I didn't know that.

ammonman

The hood switch is one of the alarm inputs as well as being a run-on safety for the engine cooling fans. For MY88 the engine bay light is switched by a tilt switch built into the bulb socket.

Mike

marinesniper0318

I live in Miami brothers and my A/C is operating at about 80% I would say an it keeps me cool even in 105F weather...now the air outlets suck, the dash blocks 1/4 of the air from actually hitting me but if I turn on the rear as well and aim the vents forward I get air from both side...

Actually I had a sore throat the first day after picking up my baby, the a/c worked well enough and that was sitting in traffic...

Lastly I am absolutely blessed with an S4 that runs at 1/4 on the temp even in 100F+ temps...so I cannot complain at all...; )

Sniper

alabbasi

Gentlemen, thank you.

Sniper, when you're paying someone $100/hr, it's very easy to rack up $2k. I'm not what I would call a good mechanic, but there's lots of little jobs on this car that can be addressed by an amateur like me before I need to farm to a pro.

So far I've
Replaced the fuel pump and filter.
Flushed the trans, torque converter and replaced the filters.
Re-built the rear axles
Changed the oil and filter
Replaced the plug wires
Pulled a vac and charged the a/c system (first time with envirosafe to see if it held, then with R12)
Replaced the voltage regulator

I expect that all of this work would have cost me much more then $3k, but I'll that money for the more intimidating jobs, like the torque tube which I farmed out.

marinesniper0318

alabbasi i here ya brother,

Ive replaced
- both power window motors
- injectors
- complete car stereo with DIN
- steering wheel
- both seats to Sparco racing
- HCV (heater control valve)
- jumpered the freeze switch
- filled the freon
- tore apart the dash and carbon fiber fabric'd the interior

But the damn A/C was something I did not want to mess with anymore in 100F humid weather here...I always try what I can first then when lost or fed up I take it to the shop...

these days I guess I am do not want to cause more damage with certain things, so I pay a specialist and its not 100$/hr its 90$/hr... : )

Sniper

alabbasi

Sounds good. I flushed cooling system today and hit the underside with a steam cleaner. I'm going to replace the battery ground with a 2 gauge ground cable and see if it helps.

I wonder if there's a way to get to the evaporator without taking the dash apart. I'd like to spray some foam based cleaner and blow it out if possible as I expect it may help a bit.

The heat here is a killer. I got about 5 hours which is about as much as I could take.