AC help needed

Icey1174 · 06-21-2007, 06:25 PM

I read through Clark's about the AC. It's pretty generic. Does anyone have the time and knowledge to walk me though the AC set up? I don't know anything about AC, but thanks to this site I have fixed everything else on this car.

No cold air comes out at all. Where do I start? I do know that if I push the snowflake button the light does light up, but that's about it. I am also concerned that my temperature selector dial may not be working. I know the knob is broken, but I cannot turn it with a pair of pliers. I wouldn't think that it should be that hard to turn.

I can turn the heat on and off. I am not sure if the valve for the heater core hose actually pinches it off or if it just closes the damper. I think it only closes the damper from what I remember. So this may add another twist to fixing my AC system.

Any pointers on where to start? I have read posts about evacuating the system. leaks, and all that good stuff. So far everything on the car has been repaired fairly easy.

Thanks in advance for any help!

mattdavis11 · 06:48 PM

I know some folks with the newer 944s have had problems with the climate control unit in the car, but you might want to start under the hood. I'd put some gauges on it and see what pressure you have. Optimum low side is 28-32 running. My guess is that you are low on charge, and need to find leaks and refill, but maybe not. If you want you can jump the low pressure switch to check everything else first, ie.. electrical gremlins. Do not run the compressor for very long w/out oil, it will burn it up in a hurry, I'd say 45 seconds, MAX.

Icey1174 · 06-21-2007, 06:50 PM

Sounds like the best idea I have heard yet! Now how do I do this?

I think Clark's has something in it about jumping the compressor. How much does a set of gauges cost and where is the low side valve?

mattdavis11 · 06-21-2007, 07:01 PM

The easiest way is to jump the switch, which should be behind the driver's side headlight, next to the drier. This will tell you everything else works fine electrically if the compressor comes on. Take the connector loose, jump the pins with a suitable wire or paper clip. I have no idea where the low side is on the later cars, on the early it is on the compressor. As a general rule, the connection on the fatter of the two hoses is the low side, the thinner is high.

Gauges... I use a friends who buys them for about $50, but he also has accounts with multiple suppliers. Harbor Frieght has some, I think.

Icey1174 · 06-21-2007, 07:04 PM

I have new struts that will be here tomorrow so I'll plan a day in the garage. I look them up on HF. Do different cars have different fittings or are they all the same?

mattdavis11 · 07:10 PM

Yours being an 87 will have R12 fittings, the others in your stable will have 134a, except for the F350, I think that may still have R12, but not positive.

I want to say all cars in the us changed to 134 in 1996.

Icey1174 · 06-21-2007, 07:12 PM

I would guess I could get different fitting to go with the gauges. Good thing I asked. I'm going to HF online now to see what they have...

Icey1174 · 06-21-2007, 07:22 PM

R134A $30 - I don't think the gauges are compatiable...
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92649

R134A $10
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95808

I don't see any gauges for R12

mattdavis11 · 06-21-2007, 07:35 PM

They are not compatable. You will need both if you plan to service the two different types.

Icey1174 · 06-21-2007, 07:56 PM

ok, I'll have to try to find the old R12 gauges...

Zero10 · 06-21-2007, 11:29 PM

Or find some R134A fitting adapters.
Step 1) Check refrigerant level / charge pressure
Step 2) if pressure is good, jumper the low pressure switch and check running pressure
Step 3) if the system engages and the pressures are correct when running, check HVAC controls

Now, if the pressure is low, have a shop find the leaks, it's better that way

if the compressor doesn't kick on when you short the low pressure switch, it could be the clutch, check for +12V at the clutch, if you have it change the clutch, if you don't, check for +12V at the low pressure switch and work your way back

Somewhere along that path you will find your problem.
My opinion is that you will find a leak, and it will probably be at/near the compressor.
In that case, consider re-sealing the manifold plate ontop, and check the fittings for leaks as well. If re-filling my advice is to use a hydrocarbon R12 substitute, they are FAR superior in many ways to R12 and R134a, I don't want to have that argument now, but I will never use anything else.

mattdavis11 · 06-22-2007, 01:02 AM

I'll bet that the front seal blew.

No arguments, please....

That's why this is such a great place, it's not an argument, it's a place to trade thoughts.

I think I might just throw some freeze 12, or dura cool in my system to see the difference. I will have to admit, the 134 holds at 54 at idle, and 39 at 2500, ambient 90. Haven't messed with it in a long time, but I'll welcome better vent temps, anytime.
I don't like tint, and have a black car in Texas, go figure.

I want to know about the Sanden units. Has anyone tried them? Fit and finish is no concern. Are they worth a damn? Lots of em in the junk bin I see.

Icey1174 · 06-22-2007, 07:41 AM

Struts just got here. I think DHL is the fastest and cheapest shipper. I am going to put them on the car first, take it for a ride then look at this AC. I am also getting some more parts in over the next week for my SC project. I have about one more month of good down time to work on this car!