barelyrunshalfthetime

I just fixed my snowflake switch so that it stays in!! Unfortunately my compressor is still not engaging. The light on the switch lights up when it's pressed. This should eliminate the switch as a source of failure right? I would like to do any kind of electrical diagnostic work I can before I need to take this to a mechanic. I tried swapping the compressor relay for another (not sure if either worked really) and no results. Is there a way to bypass the relay to figure out if that's the cause? Which pins do I jump? I'm leaning towards there being no refrigerant in the system, engaging the low pressure shut off switch. But what else can I check before having them try and charge it with costly R-12? Thanks!!

Grandpa#3

Hi, Why not just change over to R134 and have them put some dye in to see if you have any leaks in the system? What kind of repair did you perform on the switch? I wish I knew what to tell you on the relay except to buy a new one. I hope someone else can answer that question for you.

Cheers,
Larry

xsboost90

there is one wire going to the compressor clutch- it just plugs in a couple inches from the compressor itself. Check that wire is plugged in- then check that it has 12v when you engage the snowflake- it is also possible its not engaging the compressor because the system is out of gas and it is off on the low pressure switch.

Mike C.

You could unplug the LP switch and jumper the connection (just for a second to see if the compressor engages). If so then most likely the freon is gone. When did the AC last work?

barelyrunshalfthetime

Thanks for the quick responses guys! I will check the clutch wire today. Mike, where is the LP switch? The A/C hasn't worked at least since I bought the car, about 2-3 years ago. If the freon is gone, odds are that there is a leak. So do I pay to have it charged with R12, have them find the leak, then charge it again? Or do I convert the whole thing over to 134a? I've done some research in this forum and I see a lot of back and forth on the subject, but nothing definitive. How much does the 134a conversion normally cost? with no complications, that is.

Mike C.

The LP switch is mounted to the dryer can which is behind the driver's side headlight. Open the hood and look straight down just behind the headlight 'arm'. It's a cylinder about 4 inches diameter mounted to the side of the frame member. The two wires go to the LP switch. Pull them off the switch and use a wire of similar gauge to connect them together. Don't let it run for long.. To test if any freon is in there, locate the low pressure charge port (not sure where this lives on an 86 951), remove the cap and press the schrader valve briefly. If it has freon under pressure in there some will spray out (wear saftey glasses, blah, blah...)

barelyrunshalfthetime

I just jumpered the LP switch, and I found that the compressor does try to kick on. So there's no freon. What should I do? Go with the conversion to 134a? or just charge it back up with R12 (fixing the leaks)? Either way I'm going to the mechanic, I don't trust myself with A/C stuff. Anybody know how much a conversion costs roughly? I saw 600-700 dollars in one other thread, is that about right? Thanks for all the help so far.

Grandpa#3

That $600 - $700 was with a new or rebuilt Air Compressor I'm sure. You can buy A/C connection o-rings at Auto Zone or one of those places and change them out yourself. I think there are only two different size o-rings. The dryer should also be replaced $25.00. The Air Compressor if it has freon in it now has mineral oil in it. They would have to pull a full vacuum to empty the oil and put in Ester or Pag oil, and put a 90* elbow on the compressor to service with R134a. Freon is VERY expensive now. Check out the post at the link below for more information.

http://forums.pelicanparts.com/porsc...-ports-ac.html

Cheers,
Larry

944Ross

I've got Air!!

I had my condenser off as part of a front end repair, blew thru it with compressed air to remove any oil (very very little). Replaced the O-rings on the condenser fittings when I put it back together, also replaced the drier. Emptied what little oil was in the compressor, put 2 oz of ester oil in it. NAPA has excellent conversion fittings made of steel, P/N's 409902 and 409903, $7 each. (Not sure if 951's are the same as N/A, but the ports are on the strut tower -- with conversion fittings still clears the hood) Buttoned it up, pulled a vacuum, put in a 8 oz can of ester oil w/134a, then two more 12 oz cans of 134a. Pressures high/low are spot on, it is ice cold! Pressures indicate 35 - 40 deg at the evaporator. Total cost of conversion: under a hundred bucks.

By the way, on '86's at least, there are two pressure switches on the drier (actually on the pipe going to it). The second one is a refrigerant temp switch.