A/C Advice Needed...

NissanGirl · Jun 19th, 2004, 07:39 PM

Several days ago my a/c started going warm. After having a friend look at it we noticed the radiator had a pinhole leak and once we closed the hole with some JB Welding the a/c once again started blowing cold. I knew that wasn't going to hold very long (because I had closed that hole once before) so I took it in to a mechanic, he checked the a/c and said it was working properly but we would need to change the radiator, which we did. I pick up my (2000) Altima and everything is fine except the a/c doesn't seem to be putting out cold air. It isn't hot air, more like semi cool or trying to be cool (but not quiet getting there). The air is blowing nice and strong and I am wondering what the problem could be now.

Any ideas?

KA24Tech · Jun 20th, 2004, 04:02 AM

Hello and Welcome to the forums NissanGirl,
Make sure that the A/C condenser is clean so that air flows thru the core. Many times the heat exchange process is limited because of debris and dirt blocking the flow. I just take a pressure washer and spray it directly from the front of the grill on the top and the bottom but occassionally it is so clogged that you have to remove radiator to wash it out from the back.
Also check to see if the cold to hot panel control is working correctly by setting it to vent (turning the A/C off) and checking the air temp to see if it changes according to the position.
If these two things don't cure the problem you may just have to take it in and have the A/C serviced with an evac, recharge, and leak test.
I hope this helps.

Troy

NissanGirl · Jun 20th, 2004, 10:42 AM

I feel like I've just had a major breakthrough...

Twice (once last night and once this morning) I went out to check the a/c,it blew cold. I heard the compressor kick in and then once the engine heated to a certain point the compressor kick off.

I checked the engine and realized that the coolant was low - apparently the mechanic didn't put in enough coolant when he put in the new radiator. I filled it and what do you know....the compressor comes on, stays 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 wanted it to be.

Any interpretations?

NissanGirl · Jun 20th, 2004, 11:27 AM

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.

KA24Tech · Jun 21st, 2004, 03:12 AM

With the engine cool, I would pull the radiator cap and add coolant to the system and the reservior. Also the system should be bled of air and pressure tested. The high-pressure switch is the reason the compressor doesn't engage when the vehicle is warmed up because the system pressure gets too high with the heat. I would still clean the condensor core if you haven't already.

Troy

NissanGirl · Jun 23rd, 2004, 07:43 PM

Tx - I'll try it and let you know.

NissanGirl · Jul 13th, 2004, 12:36 AM

Update:

I've been to 2 different mechanics 4 times now. First mechanic changed the radiator (which had a leak), changed the high pressure switch and the expansion valve - all to no avail, sent me away scratching his head (thankfully not having to pay for anything other than the radiator). Second mechanic just changed the condenser (had a big leak), receiver/dryer, a few seals and a recharge. $600 later I'm driving it home and it's STILL not working. I've about had it with this car.

NissanGirl · Jul 13th, 2004, 11:11 AM

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!!!

NissanGirl · Jul 13th, 2004, 04:45 PM

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.

NissanGirl · Jul 14th, 2004, 09:57 PM

picked up my car from the shop today and it seems to be finally working.

Get this: SOMEONE (maybe the person that owned the car before me? Or the first mechanic working on the a/c problem?) had taped the expansion valve (with a/c tape) at the wrong end of the valve. The mechanic explained to me how this was causing a problem but I don't think I could explain it here...I'm sure those of you who know about a/c's will understand how it could be a problem.

HOPEFULLY now that they have re-taped the valve in the proper place it will work correctly (it was blowing really nice and cold on the way home - though the heat of the day had passed). If it does not continue to work we will have to replace the expansion valve - the only problem is that in my model (2000 Nissan Altima) they no longer just sell the expansion valve alone, but you have to buy the entire core. If you ask me that's just a racket!

Catman · Jul 15th, 2004, 02:50 AM

Good luck Nissan Girl! A/C can be tricky. Last year my Sentra was in the shop almost all of July and August. Just like you, back and forth for more repairs. After $850.00 of parts and labor, still not working. I know what you are talking about with the expansion valve at the dealership, but I was able to get one seperate from the core at Advance Auto. Don't have any helpful ideas. Just wanted to let you know you are not alone and I am rooting for success!

NissanGirl · Jul 15th, 2004, 02:19 PM

Catman: Thank you for that tip - I will have to check Advanced Auto...I was looking online yesterday and they seem to sell them online. I'm gonna check into it just in case it quits working on me. So far so good though. <Crossing Fingers>

KA24Tech · Jul 15th, 2004, 02:42 PM

NissanGirl,
What about all those other parts that the guys threw at your car that didn't fix the problem. Are they going to refund some of the money for parts and labor for all of that which didn't fix it?

Troy

NissanGirl · Jul 20th, 2004, 08:08 PM

Troy: No refund on anything. The only expenses have been parts and labor and all the parts have been necessary (Condenser had a large leak which I saw with my eyes, dryer/receiver).

The darn a/c is still not working. I'm at my wits end litterally. I hope I can get the expansion valve at Advanced Auto - I think I can get it online.

Catman · Jul 20th, 2004, 09:42 PM

Kinda sounds like my Sentra. I will keep my fingers crossed that it works out for you!