Rob from NH 87 S4

Yesterday, here in the Boston area, the temp was around 90 degrees farenheit.

I have a black on black 1987-S4 with the rear AC unit.

While I will say that the AC functioned, I was underwhelmed with the level of cool I received.
Both front and rear blowers worked, and I noticed that at times, the air went from a reasonably nice cool (not chilly enough) temp to what seemed like a tepid, muggy temperature. This would happen at irregular intervals, and it wasn't frequent at all. For instance, it would blow cool in the rear and the front for 10 minutes, and then I'd feel tepid mild temp air coming out of the dash, while the rear blower continued to blow cool.

Also, I will add that even at it's coolest, it was quite unimpressive. The cabin didn't cool off as I expected it to do. It made down to about 70 degrees, perhaps 68. For some folks, that may be COOL enough, but for me, no, no, no!When it's hot outside, I like it to be chilly in the cockpit.

I have read on here in more than one post that other 928 owners drive themselves crazy trying to get the system to keep them warm enough in the winter and cool enough in the summer.

I have no problems keeping warm in the winter with my 928, but yesterday, in the extreme heat, I was not happy with the results.

So, here's my question.. and I know it sounds a bit dumb, but I am a recent new owner (pucrhased in November 2001), and I have never encountered extreme heat yet in my 928.

As a new owner, should I expect the 928 climate
control system to be excellent and really cool in summer temps, or should I lower my expectations because Porsche didn't do so great a job on this portion of the car?

I have noticed that the door locks, rear hatch, windshield wipers, dash lighting - while they all function according to spec on my car - they could have all been done better. Mechanically, my car is WONDERFUL... no complaints.

Does the AC fall in this suprising category of Porche mediocrity?

Ideas, suggestions, war stories are appreciated.

Thanks!

WallyP

The odds are at least 90% that you have some vacuum leaks in the HVAC system.

Do some searching on the subject - it has been covered in great detail several times.

When the system is right, it will keep most people comfortable - with your needs, and a black/black car, you may have some problems.

Jerry 87 928S4

After I finally got my A/C fixed I checked the temp coming out of the front vent. It was 45 degrees. At this temp and with it 90 outside I was able to turn off my rear air and run the front blower on 1 and stay cool. Dash is black with grey interior.

Now I used the rear air and front on 3 to get it cool quickly - the car does attract the heat sitting.

To make a long story short, I had 3 vacuum lines leaking, both temp sensors were bad and one of the servos to a flap was also not holding a vacuum.

dr bob

AC is one of my favorite subjects, especially now since I went through and resealed the fittings, changed some parts, converted to R-134a. Even after two-plus years, I can still make ice cubes at the center vent in my black S4 in Los Angeles. All that was driven by a need to cure some system leaks, a problem fairly common in these cars apparently.

I posted some related info in response to a question from Nicole. Here's some stuff that might interest you:

Nicole wrote:

[quote]I don't know how to verify if the AC compressor clutch engages. The air temperature seems to drop minimally with the AC on, but it's by no means getting cold.

So here are a couple new questions:

In the little glass thingie next to the radiator, what color should I see - does Freon even have a color? It looks kind of greyish, no bubbles. <hr></blockquote>


Verify that the clutch is engaging:

With the engine running, you can look at the front of the AC compressor. From the front, it's the lower left side pulley, below and to the right of the air pump drive pulley. I guess that makes it the lower drive on the passenger side, closest to the engine oil sump. The front pulley is a two-section arrangement. With the clutch disengaged
(no AC) the pulley (where the belt rides) spins around the stationary center section. When the clutch is engaged, the center section spins with the belt and pulley. Watch your fingers around those fans.

Freon flowing through the sight glass:

Freon is an almost colorless liquid, and has a small amount of oil circulating in the liquid. When the compressor isn't compressing, the freon flashes to gas and is invisible anyway.

With the system running, you can see that there are a few bubbles drifting by the glass in a flow of -almost- water-clear liquid, and see streaming little trails of oil in the liquid. As the freon chrage reduces and/or the air temp rises, you may see more bubbles in there as the condenser converts a little less gas back to liquid.

'Greyish with no bubbles' usually means the compressor isn't circulating the freon past the glass.

If the compressor isn't rnning at all when you push the button:

You may be low on freon. There's a safety switch on that little tubing manifold on the drier (that's the can with the sight glass in it). On your S4, the switch is the lower of the two sensors, and has a plastic two-wire connector plugged in to it. The top sensor, the one with the two little nuts holding the wire ring connectors on, is a presuretransducer that operates the fans and the flaps in the grill (if you have them).

You may have a blown fuse, a failed panel relay, failed evaporator 'freeze' switch.

Your compressor relay in the dash controller may have failed. There's fixit writeup on the Greg Nichols website, and some comments from users with hints on a replacement relay. There's also an electrical diagnostic procedure that will help you isolate the problem.


--------------------

This info will get you looking at the too common 'not enough freon because some of it leaked out' syndrome. Cars that sit a lot also suffer from the 'no oil circulating and the compressor seal went dry and the gas leaked out' syndrome. It's a common affliction for cold-climate cars that get stored fro the winter.

Hope this helps!

<img src="graemlins/yltype.gif" border="0" alt="[typing]" />

Dozman

DR Bob, the only thing I would like to interject is that refrigerant R-12 and R-134a are both colorless. Besides that, good info to have.

Dozman
'85 928 Auto, Black <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />