Ok, last A/C question from me

Ok, it's more than one question, but here goes...
I finally got everything I was missing for my A/C; thermostat switch, compresser, condenser and hoses. The only thing left is to take it to an a/c specialist to fill up the system (I hope). Here's my questions, is there suppossed to be an a/c on/off switch? How do you turn it on? I turn the a/c fan switch but nothing happens. Do I have to do soething else? I don't want to take it to the a/c specialist and have him tell me I have an electrical problem!! I would like to make sure everything is good to go. Is the a/c fan supposed to work without activating the compresser? Sorry bout all the questions but I have no idea about these systems.
Thanks
Mike

The AC fan switch should be a two pole switch. When you turn it on, you activate two seperate circuits--one turns on a fan, one activates a solenoid in the compressor clutch that locks the freewheeling pulley to the compressor shaft. The black wire coming out of the compressor is for this function. If your switch is not a two pole switch, Porsche replacements run about thirty bucks, domestic generic equivalents proabably a third of this.

One thing I forgot to mention- If your system is empty, it's probably not a great idea to run the compressor, because of lubrication issues and moisture in the system. You can tell if the compressor clutch solenoid works by listening for a click when you turn on the system. Good Luck.

[This message has been edited by Serge (edited 07-20-2000).]

Mike,

Depends on what year and which model the system is that you are installing. I have an 85 factory system and it has two switches, both mounted on the console in front of the shifter.

The left switch is the temp switch and it tells the AC clutch when its cool enough to turn off and let the compressor rest.

The right switch is the fan switch (three position) and it actually gives the power to the temp switch to actuate the clutch.

No matter where the temp switch is, until the fan switch is turned on there will be no power to the clutch on the compressor and thus no cooling.

Another thing to think about is your dryer. If its new no problem however if you have a used dryer you need to check that its not open to the air (capped off) otherwise it will not be very effective. I have heard of people baking them in an oven at very low temps to dry them out but not sure about this.

Also, make sure that you add oil to your system... compressor needs it!

JA

I agree... don't turn on the compressor without oil & freon in it. I'm not sure about this as it applies to Porsches; but on my other cars, there's a switch that will not allow the compressor to energize unless the switch senses there's enough pressure there to work the system. Is a safeguard against ruining the compressor when fluids are too low. You probably couldn't make the compressor go w/o fluids even if you wanted to.
regards, jlex.

Thanks for the warning guys, but the thing is, I turn the switch but neither power goes to the commpresser or the blower motor. Is the fan switch supposed to turn the blower on off too? All the fuses are fine. I have the haynes but it's cr*p!
Thanks
Mike

Mike,

Go to the reference pages on the Pelican site and it will have a current flow type wiring diagram for you to look at. Often their is a relay in the "smugglers" box that has been known to go out and its overlooked.

When all else fails, ring out the wires (take a VOM at one end and a long wire to the other end of the wire and confirm that its good and not broken inside) and go from scratch. Start at the grounds, then check the power source, then go relay to relay and confirm power and you will find the problem.

If the fans do not come on, then my best guess is that you have a power input problem, but then I am on my third glass of wine and my troubleshooting skills have gone downhill a bit at this time!

The power flow is from the fan switch to the hot/cool temp switch, then to the AC clutch if memory serves me right. Confirm that you have power to the input side of the fan switch, and if so then move to check the output of the sw and then to the temp sw and so on...

Thank you for your explanation, Joeaksa. This will prove very helpful in my troubleshooting! I'll let you know what happens...
Mike

Mike,

Did some legwork for you last night... as I am working on my AC as well! Please go to "up-fixin" der Porsche volumn number 9 and on page 140 you will find two very good articles on the 911 AC system.

I am still trying to find out of someone still makes and sells the mod to the plenum or if its a "do it yourself" at home only now. If anyone has any more info on this, please post something on this URL.

JA

Thanks for the effort Joeaksa, but unfortunately, I don't have up der fixin. I did find a good diagram on pelican parts though, as you suggetsed. Thanks for that and I think I'll be able to work on it Tuesday night. I'll let you know what's up.
Thanks again everyone!
Mike

I finally had time to work on the car and found no power to the fan switch, so I checked the relay and it was rusted tight. I replaced it with a spare volks unit and it works perfect. Tommorow or thursday I fill it, we'll see how it goes...
Thanks guys!
Mike

I took my car to get filled today and the guy at the place told me that he put in 2.25 pounds of r134 and the high pressure was too high, and the inside air temp was 60 dgrees. He then let out about one whole pound and the high pressure dropped a bit and the inside temp dropped to 50 degrees. He says the reason the temp isn't any coooler is because the high pressure is too high, (from 200 to 300) and if I were to keep the rpm at around 3000 for too long, then I would surely blow a hose or something. Does anyone know what the high and low pressure readings should be? I made sure the engine lid was closed (as much as it could have with hoses sticking out) and my front condenser fan works too. It wasn't even too hot today, about 75-80 degrees. What should I do???? Help!
Mike

THe high pressure should be around max 240
You may have a plugged dryer or bad expansion valve causing problems

The original York in my system was building up a lot of pressure 250+ and locking up finally snapping belts I then switched to a Sanden which lowered pressure and solved the problem

134 operates at a higher pressure than r-12 also something to keep in mind

Do you have only 1 condenser that may also cause pressure problems since the system cannot dissapate the heat, with your pressure running that high you may have similar problems with your compressor locking, you can try carefully spraying water on the condensor to see if it helps, if so you may need more condensor

I would have him evacuate the system remove the hoses from the compressor and take the hoses off at the expansion valve while watchin at the expansion valve shoot sone compressed air thru the system and make sure its flowing freely, some shops use a can of nitrogen for this also as compressor air has moisture in it but its more expensive
Id make sure your condensors are very clean and have him evacuate the system again real well to remove any moisture to prevent icing of expansion valve etc.


[This message has been edited by jryerson (edited 07-27-2000).]

Hi, thanks for the reply, I do have two condensers though. It may be the expansion valve. Where is it located? Is there any way to check it without removing it?
Thanks
Mike

The expansion valve is located in the smugglers trunk up front, I don't know how you can check them as it takes high pressure to make them work but a new one is about $25