[968 Cab]

[quote name='Ryan' date='Aug 3 2006, 06:57 AM']Correct me if I am wrong here, but if you are low enough to trip the low pressure swith on the system, the compressor in not going to run. How are you going to see any activity through the sight glass if the system is not working???



I had the system in my 944S quit on me and I hooked up a can of 134a to the low end with the car running and the A/C switch on. At first the compessor would not come on, but after the can of gas brought the pressure up to the point of bypassing the switch, it kicked on and sucked the can dry. System worked after that.

[right][post="24940"]<{POST_SNAPBACK}>[/post][/right][/quote]



You're correct if the system is so low on charge or oil that it is virtually dry - stops the compressor from running without any lubrication. However, from my experience if there is still oil in the system or a trace of R12/R134, the compressor still operates and you will see a bubbles or foaming in the sight glass.



If you have pressure gauges, you get a definitive reading. Some of the aftermarket setups are pretty decent and come with rudimentary gauges that provide a range of readings (low on charge, Normal, high, danger) for recharging. They seem to work well enough when charging, and the foaming in the sight glass dissappears at the same time as the gauge registers "normal".

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[Ryan]

Cut-off is pressure based and the system can still be full of oil and not run.

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[frank moran]

[quote name='Ryan' date='Aug 3 2006, 11:03 AM']Cut-off is pressure based and the system can still be full of oil and not run.

[right][post="24947"]<{POST_SNAPBACK}>[/post][/right][/quote]



that is correct, if all the wire etc. is in place and functioning you more then likely have a leak. Go to autozone get a can of 134 with dye in it, put it in on the LP side at the compressor. Buy the little UV light for $12. and look for the leaks. I suspect the front comp. seal is leaking or the compressor case seals, this is an easy repair, cost about $40. for parts. Mine leaked at the comp and at the condenser.

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[barth7]

From Cab's reply on the first page.



1.Okay, I do have a sight glass. Took some implements to get it to where I could see it, though. I cranked the car & the AC and I really couldn't see any flow or bubbles or anything.



2.Fuse was okay



3 I could hear the relay clicking, but I donb't know if the clutch was. Maybe not. Need to recheck this.



4.Didn't pull the relay yet. Like I said, I think it is working.



5.Will have to look for this one now.



So, still checking things

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[Ryan]

I would do as Frank said and get some 134 with a dye. I t sounds like your system shut down due to low coolent pressure. If there is no oil covering your compressor, then you should not need oil for the system. You most likely have a leak at an "O" ring somewhere.

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[968 Cab]

[quote name='Ryan' date='Aug 4 2006, 06:09 AM']I would do as Frank said and get some 134 with a dye. I t sounds like your system shut down due to low coolent pressure. If there is no oil covering your compressor, then you should not need oil for the system. You most likely have a leak at an "O" ring somewhere.

[right][post="24972"]<{POST_SNAPBACK}>[/post][/right][/quote]



Sounds right... probably a leak somewhere. I've seen the HP line from the compressor split, but that would cause a loss of the oil in addition to the R134. Get 3 cans of the R134 with dye - if there is a leak, you'll know pretty quick after adding 1 can. If you lost all the refrigerant somehow, you will need more than 1 can and it is not expensive.



The only caution is that R134 is nasty stuff - apparently know to cause testicular cancer...... so be forewarned!

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[barth7]

Well, an update. I am getting 14v to the compressor when craked, but the clutch isn't kicking in. However..........I may have determined the problem. My 944 building buddy suggested I might havea clog in the system. I am starting to agree. When I first checked the LP line by the compressor I have over 100 psi. Don't recall the exact #, maybe 110. So, by his suggestion, I drained some of that pressure off at the LP fitting. Got it down to about 40 psi and then took it back to 70 psi with my can of R134A. Still nothing. I think the next step is to find somebody with gages to check the HP and LP side to see what's up.



-Bart

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[frank moran]

[quote name='barth7' date='Aug 5 2006, 11:39 AM']Well, an update.  I am getting 14v to the compressor when craked, but the clutch isn't kicking in.  However..........I may have determined the problem.  My 944 building buddy suggested I might havea clog in the system.  I am starting to agree.  When I first checked the LP line by the compressor I have over 100 psi.  Don't recall the exact #, maybe 110.  So, by his suggestion, I drained some of that pressure off at the LP fitting.  Got it down to about 40 psi and then took it back to 70 psi with my can of R134A.  Still nothing.  I think the next step is to find somebody with gages to check the HP and LP side to see what's up.



-Bart

[right][post="24996"]<{POST_SNAPBACK}>[/post][/right][/quote]

Barth, the LP side sitting in the sun in Ala on a 90 degree day is going to be close to the readings you have, the LP side only drops when the system is functioning, go get some 134 put some in and see if the system operates, again you may have have a leak. The system is protected by a LP switch that prevents activation if the system looses pressure.

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[barth7]

I had the car cranked and AC on when I checked 110 at one point. It wouldn't take any more.

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[frank moran]

[quote name='barth7' date='Aug 7 2006, 02:26 PM']I had the car cranked and AC on when I checked 110 at one point.  It wouldn't take any more.

[right][post="25041"]<{POST_SNAPBACK}>[/post][/right][/quote]

was the compressor activated? as your putting 134 in if it was low it would cycle a few times, are you sure your charging on the LP suction side of the compressor.

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[barth7]

I think the compresser isn't activating. Fuse & relay okay, but I think the clutch isn't kicking in.

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[968 Cab]

[quote name='barth7' date='Aug 8 2006, 06:05 AM']I think the compresser isn't activating.  Fuse & relay okay, but I think the clutch isn't kicking in.

[right][post="25076"]<{POST_SNAPBACK}>[/post][/right][/quote]



Check to make sure the wire to the compressor clutch is still connected at the compressor (you'll see the black wire connecting to the compressor from underneath the car). It's surprisingly vulnerable to being disconnected, broken, etc. If it is connected, check to make sure it is getting current when the AC is switched on.

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[rhudeboye]

I have a 94 and I'm having the exact problem with the exact symptoms. I got a 2 pack of 134a and Im ready to give this a try.



FYI I'm truly a novice mechanic, so pardon the stupid question. On the pic of the drier in this thread theres a tube with a black twist cap on it. Is that the spot where I add the 134a? according to the instructions on the package I should see a black or blue cap but it adds between the firewall and compressor.



For what its worth my car has the little window on the drier.



edit/update

The cap on the 134 doesnt fit so I assume that the cap coming off of the drier is the HP hose.



So wheres the smaller LP inlet?

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[frank moran]

[quote name='rhudeboye' date='Aug 8 2006, 09:57 AM']I have a 94 and I'm having the exact problem with the exact symptoms. I got a 2 pack of 134a and Im ready to give this a try.



FYI I'm truly a novice mechanic, so pardon the stupid question. On the pic of the drier in this thread theres a tube with a black twist cap on it. Is that the spot where I add the 134a? according to the instructions on the package I should see a black or blue cap but it adds between the firewall and compressor.



For what its worth my car has the little window on the drier.



edit/update

The cap on the 134 doesnt fit so I assume that the cap coming off of the drier is the HP hose.



So wheres the smaller LP inlet?

[right][post="25084"]<{POST_SNAPBACK}>[/post][/right][/quote]

NO, add it down at the compressor on the suction side, drop the plastic panel and you will see two hoses....now let me say this is where i charged my 92, the compressers are the same. Look for an S on the comp, I believe it was the bottom hose. Also typically the LP side has a larger hose...possibly you have a differnt layout, one other thing is the charging hoses can only go on the correct fitting, the LP and HP connectors are different.

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