2000 Nissan Altima A/C Questions.

I bought my 2000 Nissan Altima a couple months ago from a good friend who owns a dealership. When we bought it the radiator had a pinhole leak which we closed with a little JB Weld. Just recently my a/c started running hot and cold off and on, I took it back to my dealer friend and he tried to put some freon in but it wouldn't take it...there was too much pressure built up in the system and he said the compressor would come on and off. He let a little pressure out and continued trying with no avail. We realized there was anothing pinhole leak again in the radiator and we put a little more JB weld on it - after that the a/c worked like a charm.

I knew that I should still get the a/c and radiator checked so I took it to my dealer friend's mechanic. He tested the a/c with the hose/guage thing (forgive me I don't know what it is) and said the a/c is running properly but the radiator should be changed which we did. I picked up the car and the entire way home it blew air strongly but not cold air, just barely cooled air. My husband says he hears the compressor kick in when I turn on the a/c - though I don't hear it. He's probably right as I know little about vehicles.

I just went outside and started the car again and it blew nice and cold for a couple minutes and then went back to the barely cool air.

Any advice would be greatly appreciated. I feel like I've just had a major breakthrough...

This morning I went out to check the a/c again...again it blew cold (this time I heard the compressor kick in so I know I was right in saying it wasn't coming on last night when my husband said it was). Once the engine heated to a certain point the compressor kicked off. (Same thing that happened last night when I tried it.)

I checked the engine and realized that the coolant was low - apparently the mechanic didn't put in enough when he put in the new radiator. I filled it and what do you know....the compressor comes on and the a/c blows cold air!!!

Apparently when I had the pinhole leak in the old radiator and not enough coolant in the new radiator the compressor would only come on when the engine was as cool as the compressor liked.

Any interpretations? Argh! Now when I check the a/c again the compressor isn't kicking in - my guess is that the coolant I had just put in the radiator resivor was keeping it cool, as soon as the coolant heated up the compressor won't kick in anymore. antifreeze - coolant, has absolutley nothing to do with your air conditioner. This is to seperate problems. I would get this car to a different mechanic, if the mech. says that the coolant being low made the a/c not work. The mechanic did not say it had anything to do with it. My point was that when the vehicle gets to a certain temperature the compressor kicks off. When I had put in new antifreeze it cooled the temperature down somewhat and caused the compressor to kick back on. This is not the only time this has happened...in the paragraphs above I explained that the compressor seems to kick off when the car gets to a certain temperature.


We are not overheating and the temperature gauge actually reads slightly below the halfway mark.

I talked to someone at the parts store today and they believe either the low pressure switch or the clutch cycling switch is faulty. As one of the posts mentioned Radiator coolant (antifreeze) has
nothing to do with Refrigerent.....He is correct.

But also there may be a Temperature sensor(s) associated with the
Radiator. This sensor(s) could be in Series with the Clutch cycling
switch. Sometimes the FANS are intrerlocked with the A/C System also.

without the Factory manual in front of me its hard to diagnose the
problem. Take the vehicle to a A/C mechanic.

Gl Sounds like to me that it has something to do with the condenser fan/s. These are the cooling fans infront of the radiator. If they are not working, the refrigerant inside the condenser is not being cooled and the hi-side or head pressure builds until the hi-pressure switch cuts off the compressor. The A/C will run for a short period of time until the head pressure reaches a certain psi, then cut off. Have the fans checked.


transman Thank you, I'll talk to my mechanic about it.

Update: So far we've had the High pressure switch changed, the Condenser (had a hole), the expansion valve and the receiver/dryer changed and STILL not working - I'm $600 into this and been to 2 different shops and am getting sick of this. what are the pressures when the compressor clutch goes off and on
again. Have you mechain check amperage draw and voltage at the
compressor clutch! what are the pressures when the compressor clutch goes off and on
again. Have you mechanic check amperage draw and voltage at the
compressor clutch! IT's WORKING NOW!!!

Took it back to the mechanic this morning. They felt
that maybe the a/c relay switch faulty - somehow they realized it was an electrical problem. They hooked it up to the computer and it showed that the break was coming from one of the main sensors which was getting an error code from the transmitions speed sensor and shutting down the a/c relay. (Ok I'm no mechanic but that was the basic idea.) Not too long ago I had accidently put the car in 2nd gear and hit the freeway...I noticed something was wrong when I was hitting 6000 RPMs...I looked down after about 20 seconds and realized that it was in 2nd gear. The mechanic thinks that is when the computer put out the error code. Anyway, between resetting the computer and changing the compressor it is now FINALLY working!!! good.

NissianGirl I'm having some of the same issues. Around how much did it cost you to get it fixed? I just want to make sure I'm prepared to get this fixed. i am in the middle of repalcing the A/C Compressor on a 2001 Grand Caravan. I bought thecompressor(with a warranty) used since a new one was triple the cost but this is my question. i was told to replace the drier and flush the system. Which didn't seem to bad but when i called one of our shops they said i had to replace the front and back values also. the estimated bill 853.00. Can you tell me besides the Compressor it self what else needs to be done. Well maybe I spoke too soon. Can you believe this? I got back into the car this afternoon and what do you know, it's back at it's old thing...compressor kicking on and off. I call the mechanic and he says "Don't turn the car off (cause it will reset the computer). Drive here now and we'll hook our computer up to see if we can read what error code is being sent out. I get there and no error codes. It's sitting in the garage now as he looks over the readings. He says he thinks it might be the termostate sensor or something like that. I'll keep you posted.


Ckr2323: So far the bill is at $620 (I got a discount cause my neighbor owns his garage shop). Condensor is almost $300, Receiver/dryer is almost $100 and then there are a few seals and freaon.