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.

[I_love_my_95_pathy]

I own a 1995 Pathfinder LE and I was having a similar problem with mine. What I did to fix mine was I replaced a few of the easier to get to o-ring s and took a tire valve core remover to tighten the low side valve core.

 

I did it this way for many reasons but for the purpose of testing and avoiding having to dismantle the a/c system. Try tightening the low side port first to avoid that as a leak point then either add a small bottle of r134a or a leak detection fluid. If you add the r134a and the compressor immediately kicks in like it did in my case then your all set. If it doesn't then I would change all the orings

[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

[Motofish]

Stay away from the stop leak stuff. It only ever made my systems fail after a short time. If you have a leak, replace the oring. Otherwise id stick with recharging it with plain old freon. I had an issue with my '93 where it was freezing up due to moisture in the system. I took it to pep boys and had them evac and refill the system for like $50. Took care of the problem. If youre going to open it up and replace the orings, id just have the system purged and filled afterwards.

[RedPath88]

Do it right, if your going to open up the system then have it properly purged before doing so, many shops do it and it does not take long.

 

 

I don't know if 94's came stock with R134a, but it is possible that someone converted it in the past (unless your the original owner).

 

And even though you have found the answer to your own question... yes, the compressor has a pressure cut off to prevent it from running when the system is to low. Along with the coolant there is an oil added to the system and that provides the lubrication for the pump. So if the level is to low then the pump risks damage if ran without proper lubrication.

 

I converted mine quite a few years ago, reusing the same seals, just having the R12 evact'ed, added the R134a valve adapters, just before filling I put a vacuum on it myself to be sure (it had been a week or two since I had it purged), and then refilled with store bought R134a and oil (this was a kit that included the adapters, R134a and oil) but I also added stop leak and have had no problems.

 

You could just pick up a can, top it off and see if it becomes a problem later. If it does, then deal with seals and such later, if not then you saved your self a bunch of time and money.

 

If your system was R12 originally then you "should" have a sticker designating the R134a conversion over the original R12 sticker. You can also tell by looking at the high valves, if there is a screw on adapter on the welded on one then it's been converted.

[Pav]

I just had mine fixed a little while ago. Ended up being the condenser was finished/leaking and needed to be replaced. Replaced it and got it filled up and now blows cold. I would have it checked out and get a few quotes to have it done. A/C systems are pretty hazardous to deal with.

[brc19761]

Ok just got finished with the job. I got some really good Freon with leak stop and so on in it.. I came home put it in and it wasn't enough. So, I had to go back and get two regular cans of 134a Freon. When I got back I heard a hissing sound coming from the truck. It was leaking on top of the compressor. I found the part screwed it out and figured it was the o ring. I took the part and got a set of a/c o rings and found one to match the old one. Screwed it back in and started with a can of Freon. This time I put a little Freon in and stopped and turned the truck off. Same hissing noise from same place. Two cans of Freon gone down the drain. Got to investigating a little more and found another o ring leak. This time put some Freon in and turned truck off. No hissing noise. Leaks were stopped. Now back to the store for more Freon. Put two cans in air got cold and so did the a/c lines. Still no leaks. Took paper clip out and hooked up dual pressure switch. The clutch is now engaging on its own and I have cold air blowing on the inside. I still have one can of Freon left to top the system off, but I decided to let the truck set overnight and see if the leaks come back or any other leaks start. I have a working clutch and cold air again or at least so far.

 

I will let you know how things go tomorrow. Thanks for everyone's post and input.

 

brc

[RedPath88]

So you opened up the system?

 

The glaring issue I see here is that you did not put a vacuum on the system once it was closed back up, which means you did not get enough back in. At the minimum, it's probably not going to cool as good as it should, and you likely have air and other contaminates left in it

 

[adamzan]

You can't just keep jamming more refridgerant in without measuring the pressure. You at least had a pressure guage on your charging hose, right? The service manual has the correct pressures for the various ambient temps. If you over charge it the pressure will be too high and you could pop one of the lines.

[Terranovation]

Also that gas is illegal to vent into our precious atmosphere.

[Slartibartfast]

IIRC it's illegal for a shop to vent it, kinda grey area for private work but still better to have it evac'd professionally. It's not an ozone depleter like R12 but it is a pretty effective greenhouse gas. Adamzan, sounds like he's using the little nozzle things with the gauge built in--not professional grade but it does give some indication.

 

Air left in the lines isn't ideal but I don't know whether that'll bite you. A lot of the air probably got flushed out during your failed charging attempts. Might've been smart to replace the drier though.

 

I'm not sure when the R12-R134A changeover was, but my '95 and '93 are both R134A, and I haven't noticed any obvious adapters or anything. The last R12 rig I remember dealing with was my grandma's early 90s Subaru Legacy.

[adamzan]

1992 was the last year for the pathy to have r12 i believe. I just pulled an a/c compressor off a 93 in the JY and it was r134a as well.

[brc19761]

Thanks for all the replies. I know I needed a vacuum pulled. That was the first thing I thought. I drove my Pathfinder yesterday and it blew cold air the whole time. I kept checking for leaks and so far have not found any.

 

Do you think I really messed up my a/c by not having a vacuumed pulled? Do you think my a/c or any related a/c parts will fail earlier than they should b/c of my stupidity? I strongly value the information on this message board. Everyone has did a wonderful job of helping me in the past. I usually do not cut corners at all when it comes to my vehicles. It is no excuse, but I am in the process of moving and I was running out of money and time fixing the a/c this week. This Pathfinder is in to good of a shape for me to screw things up. So, if you think I got someone to pull a vacuum now and re-charge the a/c it would do any good at this point? Or should I leave it like it is?

 

I really value your opinions and information. Any input would help.

 

Thanks,

 

brc

[adamzan]

If moisture gets into the system it will ruin the dryer and allow acid to form on the inside. It won't be something that happens over night but it will cause components to fail eventually. If it were mine, I would charge it with some dye, find all leaks even small ones, and repair them, and then pull a vacuum/recharge. The thing with small leaks is they can take months before you even notice any r134a is gone, performance wise.

[unit6usa]

I would definitely get a vacuum done on it. It shouldn't be that expensive but I had a friend lend me his stuff to do it Also, to speculate on another thing, it is my understanding that the clutch does not engage when it is low on freon. I had some trouble with my a/c a week ago and, after looking at the FSM, it turned out to be something simple like a fuse or something, I've had a couple beers since so...