rosenfe

on my 79,ac not hooked up.does anyone else experience a hot cabin while driving.?will isulation on interior firewall help dynomat etc

hlee96

Heater valve working? Is the air coming out of the vents get warm after the engine gets warms up?

Or do you feel heat radiating through only the footwell or the transmission tunnel?

rosenfe

i will check if coming through vents.if so ,with fan off and heat slider off,what does this indicate?

James Bailey

a leaky heater valve....under the air cleaner assembly near the firewall. Also change the short hose from the cylinder head to the heater valve they often are neglected and burst every 10-15 years or so.. If lots of heat around the console odds are the large foam insulation on top of the torque tube around the shifter is damaged or missing and if the widows are open it suck tons of heat off the engine and exhaust right into the car.

James Bailey

That said there is a reason why virtually ever USA delivery 928 was fitted with A/C....and many with an extra rear ac unit. The amount of rear glass and smallish side windows makes for a very hot car.

Speedtoys

"my interior gets very warm on hot days"

Yup.

Adk46

Yup, yup.

Sometimes I wish the engine was in the rear, like a proper Porsche, so its heat could escape harmlessly.

UpFixenDerPorsche

Yes, they get ***** hot.

A lot of heat enters through the rear hatch glass. I have tint film on door, quarter, and hatch glass, and in addition I have One Way Vision film applied externally on the hatch glass; The OWV made a very noticeable difference on A/C load.

In the near future I plan to refurbish the insulation on the entire floor and inside of firewall. There have many advances in heat and sound deadening since our cars were built.

A huge heat source is the exhaust system, especially the manifolds. So I'll also be heat wrapping the entire system as part of this project.

UpFixen.

The Forgotten On

I replaced the loose insulation on the firewall of my 81 with 3M Thinsulate (same sh*t Rolls Royce uses) and it helped to drop the temps some and funky old car smell a lot.

I would upgrade this first so you can get rid of any unwanted odors and keep heat from getting in from the engine bay.

I then had the windows tinted about 2 years later with Suntek Carbon and it has helped a lot with keeping heat out as it rejects and absorbs way more heat and UV rays than standard tint ever will.

My car could actually cool off with the AC on for once on a hot day. A pricey upgrade, but worth it.

Other than that I would get your A/C operational.

James Bailey

With out A/C you are toast.....literally ! My wife's 1979 was fine in summer Las Vegas heat.

linderpat

is there an easy way to fix the insulation at the shifter/torque tube without dropping the tube from underneath?

zaevor2000

With so much slanted glass area on the vehicle, it becomes an oven in hot weather...


It is what it is...

FredR

The black bulb temperature that results from solar radiation is 82 degrees C give or take a little. Thus even with cars that have a/c's working as designed the sensible thing to do when getting into a heat soaked car is to run for the first few minutes with the windows open- this gets rid of the silly heat far quicker than relying on the a/c system.

If your a/c system does not work then in hot weather you are going to be sat in sweat- no ifs or buts and that is the bottom line. Fitting heat resisting film does not stop the car from heating up but it does enable the car to cool down noticebly quicker as the heat is being removed quicker than it is entering the car.

When working as designed the 928 a/c system is actually quite a good system with an excellent Nippon Denso compressor- probably as good as they get. The limiting factor for the a/c system is the condenser surface area at the front of the car.

Models with automatic transmissions have a smaller condenser due to the space taken by the cooler and thus are not as effective as the manual transmission models [GTS manual excepted as that also has a transmission cooler].

Running without the a/c system in the 928, especially in a warm climate is just futile misery. Getting a knackered system working again is no small undertaking especially if the evaporator has gone south.

For anyone contemplating a/c work we have a very knowlegable chap on the list [Griff] who regularly chimes in on such issues and is a good resource for custom a/c parts. I have also heard of folks being able to get upgraded condensors fabricated but no specific experience or have added auxiliary condensors. Indeed one chap out here rebuilt an early 928S and fitted a condenser at the back of the car [removed the front one]. To my surprise it did not look too bad and it ctually worked rather well.

The optional factory auxiliary rear a/c upgrade package is a bit of a moot point- it is useful if you cart kids along in the back seats but in reality the additional duty detracts from the front a/c performance so you stil get the same duty just in differnt parts of the car.

Rgds

Fred

linderpat

My question wasn't really an a/c question, but a mechanical fit question about that piece of insulation under the shifter that over time deteriorates. Can it be fixed without dropping the torque tube?

Majestic Moose

No, but you might cut it in half and squeeze into place from both sides. Good results are unlikely and it would not be worth ruining a good piece of foam. Better off waiting to do it right.