What Just Happened To My A/C

[brc19761]

I have a 1994 Pathfinder LE v6 with 92,000 original miles on it. I drove the truck last Wed. and Thursday about 200 miles both hwy and in the city. The a/c performed perfectly as usual. I get in it Sat. to go to a 4th of July cook out and the a/c just blows hot air. I have the push button auto a/c controls. I pushed the a/c button on and off and I could feel the compressor kick in, but no cold air. I turned around and came back home. I went to check everything out more closely today. The magnetic clutch is not engaging at all. I closely read the HA section of the factory service manual. I checked the a/c radio fuse. It was not blown and radio works fine. I checked where the a/c relay goes with a test light and it is getting power. I also switched the blower and a/c relay and the a/c relay worked the blower. I did unplug the ac connector and the magnetic clutch connector and tested it with the test light and neither would light up. I know I need a 12v multi reader to check the a/c, clutch, and thermal protector to see if each one is getting 12v. I looked everywhere in my shop and could not find my 12v meter. But like I said I did check them with a test light and nothing lite up.



Next, I removed and disconnected the push button a/c and heat controls. I put in a back up control panel I had and everything worked on it. For, example it changed the air flow, it changed the blower speed, but I pushed the a/c button and the clutch would not engage. I noticed that all of the relays except the a/c relay would get warm.



If the Freon gets low will the clutch not engage on the compressor? I know the r-12 or either r-13 (I can't remember which # it said on the a/c lines) you can no longer get unless you have a license. So, unless I convert the system to a 134a and have a vacuum pulled and put new 134a I cannot see if adding Freon will make the clutch engage.



Does anyone know what else I could check or what else it could be if the clutch and compressor was not getting power? Can you buy just a a/c clutch or do you have to buy the whole compressor? If the system is low of Freon will the clutch still engage?



I would like to try and diagnose the problem myself b/c if I take it to a mechanic it could be tons of money that I do not have right now b/c I am in the process of buying a home and moving.



Any information would be appreciated.



Thank You,



brc

[brc19761]

I apologize. I just went outside and read the label on the a/c line and it says use 134a. I really thought that a 1994 vehicle would have the older type of Freon. So, all I have to do is check the Freon level and see if it is low. I know you need a set of gauges to test the Freon level. All I have is a blue hand grip gauge with a hose that attaches to just one a/c line and you squeeze the leaver and it tells you if it is high or low of Freon. Would that work? Only other gauges I have is to test my outside a/c unit on my house.

[brc19761]

OK what I did was the paper clip trick. I unplugged the dual pressure switch (low pressure switch if that is what you want to call it) I bent a paper clip into a u shape and placed it into both terminals. This made the clutch cut on. I could even make it cut on and off by pushing the a/c button on and off.


So, I know it is low on Freon. Should I add some Freon with stop leak? Do I need to keep the paper clip trick going so the clutch will be running to take the Freon. Or could you plug the switch back up and by adding Freon would the clutch kick in?


Thanks,


brc

[4xq]

Yep, go ahead and add a can of freon, but I would not use the stop leak.

It's pretty normal for a system to lose a little freon over a long period of time. So just adding some freon should mean you will be good to go for quite a while. I have done that to my 02 Qx4.

The other reason not to add a stop leak is because if you have a large leak ( your new freon will leak out pretty quickly) you will need to have the system fixed. The A/C guys test for stop leak and some shops won't work on them if they have stop leak in them. Stop leak is last resort only.

Using the paper clip trick while you add is fine since you know how to do it.

Pretty good job of mechanicing there!

[atraudes]

Clean all of the A/C hoses and connections as best you can before refilling. If the fluid starts leaking out again it'll be a lot easier to spot with clean hoses. The refill kit I bought had UV dye and a black light to assist with finding the leak, and it actually worked

[brc19761]

Just an update on what happened with my a/c. Well I went and got some good Freon without stop leak, but with other things in it than just a regular can of Freon. I put that in, but realized I needed more Freon. I went back to get just some regular cans of 134a. When I got back I heard a hissing sound it was coming from the top of the compressor. I noticed that it was a screw in valve that was leaking. So, off to the parts store b/c I figured it was a bad o ring. I got a assortment of a/c o rings and more Freon. Replaced the o ring on the valve and screwed it back in. Put a can of Freon in and there came the hissing noise from the same valve. It took me a minute, but I saw that the part the valve screwed into had some bolts to take loose. In it was a larger O ring. I replaced it. I slowly put another can of Freon in. This time no hissing noise. It was leaking in two different places.

I put enough Freon in to get the air cold. I parked it overnight to see if there would be anymore leaking. No, leaking so I put about a half a can of Freon in to fill the a/c system close to capacity. I did not want to push it and have it start leaking again or create other leaks.

It has been blowing cold air for about a week now. The only thing I didn't do is pull a vacuum and refill the a/c system. That was my fault. Eventually to eliminate premature wear and just for good measure I will have a vacuum pulled to get any air that may have entered the a/c system and refill the a/c to capacity.

brc