AC Sometimes Works and Sometimes Doesn't

[peglegtom]

Having an issue with the AC on my 99 SHO. Sometimes it will work normally, blowing cold air. Other times, it doesn't work, and no cold air is produced. This can happen while driving the car (the AC may be working fine, then shut off, then start again). Other times, it won't work after re-starting the car, even though it worked fine prior to stopping. Of course, it always seems to stop working when I'm driving a long distance in hot weather (this is not an accurate observation, just a snide comment).

The blower motor continues to run and blow air under either circumstance, it's just hot (ambient, not hot from the heater) or cold. Changing the settings or shutting down and re-starting the AC doesn't seem to make any difference.

Any help would be appreciated.

Thanks!

Tom

 

[sperold]

You are low on your refrigerant charge, maybe down a pound (or two).

Take it to a first rate shop but get some prices first.
To evacuate your system and install a dye refrigerant is usually about $70.00. They run if for awhile and put on the yellow glasses, and use a black light, to find out where the leak is.

The refrigerant top up is usually around $30.00 (around 1.75 pounds).

Where you live, a common issue is leaking around the compressor shaft seal when the temperature hits minus 30. In that case, you won't find the leak in the summer and the dye test will come up with nothing. However, the dye remains in the system, and if it leaks out in the winter, the guy with the yellow glasses will see traces of it next spring.

 

[E1]

You need a shim-ectomy.

Very common.

Go here. Don't spend a ton of money at a shop until you remove the spacer shim behind the clutch on the ac pulley.

http://www.v8sho.com/SHO/ACClutchAdjustment.htm

 

[98SF19]

Here's a pic I took after removing my shim (didn't fix the problem)
https://dl.dropboxusercontent.com/u/50438230/Shim.jpg

It would be worth running this test as well (see below). A new blend door actuator is inexpensive, but I've read of cases where the door flap itself had binded, in which case the new actuator's would fail shortly after installation. I *think* this is more the exception than the rule though.
http://www.idmsvcs.com/2vmod/eatcswap/selftest.html

 

[peglegtom]

My Shop indicated that the Freon Level is OK

and is thinking that the compressor clutch is the problem, however, they are talking about replacement of the compressor because you no longer can buy just the clutch. I'll talk to them about the spacer issue and see if they're willing to give it a try (they work on my Alfa 164, so they're not afraid to tackle something different). If not, I may give a try myself. Sounds to be much cheaper than a new compressor (and condenser and dryer to keep the compressor warrantee in place).

Let you know what they say.

 

[peglegtom]

Traced problem to the AC Compressor Clutch

Managed to take the SHO into my garage with the AC not working today. A pry bar applied to the clutch caused it to engage and blow cold air. Therefore, the problem is associated with the clutch. The garage says that they cannot get just the clutch, and would have to install a new compressor and associated parts required to maintain the compressor warranty. However, they are willing to install just a clutch if I can locate one. I checked Rockauto, and they just have the coil, not the complete clutch. A brief search revealed that Parts Geek has clutches, but they just list them for 3.0L engines and have two with two different prices.

Does anyone know if a 3.0L clutch will fit the SHO (3.4L V8, 1999)? If not, does anyone know where I can purchase an AC clutch for the SHO?

Thanks!

 

[Ian Macoomb]

Not sure but the SHO used a fancy Sanden compressor the SLO versions did not so the clutch is not likely to be the same. Years ago I was looking at other cars that used the same model of Sanden compressor and there were other cars that used it. Honda Del Slo comes to mind as one that did and should be readily available. Not sure if the clutch would be the same though. Perhaps it's possible to have a company that does clutches or brakes do a custom clutch rebuild.

 

[peglegtom]

Purchased a SHO Specific AC Compressor Cluctch

from Autopartstomorrow.com, which had the lowest price for an avaiable part. It was $200 approximately with free shipping, although I bought the optional secondary shiipping. This was the cheapest I was could find on the web for an official Motorcraft part. Apparently,this part is NLA from Ford.

Apparently, this part is SHO specific.

 

[E1]

Take



out



the



shim ! ! !

 

[RonPorter]

Removing that shim will make it work in most cases, but that just buys time until it goes again. If you plan on keeping the car awhile, might just bite the bullet and go with new parts. Then save the old as a spare, and you can remove the shim at your leisure.

 

[Ian Macoomb]

Buy the damn clutch if you can get it that cheap.

I wish I would have. I replaced everything but the clutch and it would only engage at idle even with the shim removed. Then it would freeze up after a while and I'd be stuck with no a/c until the next rest stop. Made for a hot road trip to Seattle in 2008.

 

[peglegtom]

New AC Clutch Did Not Solve the Problem

After the new AC clutch was installed, if anything, the problem is worse. Now, the AC will work with the engine cold, but seems to conk out either when the car is re-started when warm, or sometimes, just when driving after the engine has reached temperature. I suspect it's something in the wiring that sends power to the AC clutch. A broken wire could connect sometimes and not at other times. The AC compressor was removed to install the new clutch, and this could have affected the nearby wiring.

Rock Auto has three different AC clutch connectors that apparently differ in the wire lengths and connectors at the end opposite the connector. This is a 4 wire connector that attaches to the end of the compressor opposite the drive belt. Not sure if this is the problem, or if other wiring in the area could be the problem.

Now down to grasping at straws. It's certainly a PIA to have the AC crap out at the worst possible times.

Would appreciate any ideas. If you feel replacing the 4 wire AC clutch compressor connector is a possible solution, has anyone done this and where do the opposite end of the 4 wires conncect?

Thanks!