Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

iza425:
I've owned my 2000 Xterra for 8 years now and I never had any problems with the truck until now. It has over 100K miles and I just started having AC problems. The AC had never been serviced before. It started making a faint squeking sound (or hissing sound) that comes from the two center vents in the dash and it takes a VERY long time for the AC to barely cool off when I'm driving on the highway. When I shut off the car, it continues to sqeak for about 10 seconds until the sound finally dies off (almost like a bad engine that keeps running after it's turned off). I checked under the hood and I can hear the same squeak coming from somewhere by the firewall. The clutch turns on when I turn on the AC, and water drains out the bottom of the truck as it should when I stop driving.

Sometimes when I'm driving, I turn the AC off then I turn it back on and it blows cooler but it never gets cold. The squeking sound is always there but the sound always goes from louder to quieter continuously.

This is the weirdest thing I've ever encountered with a car. I have not taken the truck anywhere to get it looked at because I don't want to get ripped off. I'm selling it in a couple of months (purely because of the gas prices)and I don't want to spend any money on it unless it's minimal. However, anybody that's going to look at the truck is going to hear the sqeaking sound and I don't want to lose the sale.

Can someone help me? Can it be the Thermo Control Amp problem? None of the postings mention any noise continuing after the car is shut off.

Thanks!

yobbery:
2000 Frontier
Exact same problem in every detail.

I had the fan restistor replaced 4 years ago because the blower motor would only work on the high setting.

Please let me know if you find the cause. I'll do the same.



Update: My highside pressure line was leaking at the compressor. Replaced the line and re-charged the system. Nice and cool now. I just hope it lasts.  

I have a 2002 Nissan Xterra V6 SE.  My A/C had similar symptoms:  My A/C would not work when I firsted start my truck.  You could hear the compressor switching on and off quickly(click-click...click...click)  Then, after between 3 and 20 minutes it stay on and my A/C would work great! (Nice and cold) for the rest of the trip.  

Because of this fact I knew it wasn't freon leak related.  It had to be a sensor or switch somewhere in the system.   So, I googled your blog and found the similar systems fixed by the Thermo Control Probe amp.  

I went to the dealer parts counter in hawaii and asked for a "thermo control".  the clerk said, "Oh thermo control probe amp for the A/C? Yeah, we have that in stock."  Apparently it's a common problem.  

Since it's probably one of the cheapest parts in the A/C system,($47) I just bought it and changed it myself.  20 minutes later my Truck was fixed!  

I just wanted to say thanks guys!  

I to have the intermittent AC problem where the compressor clutch may or may not engage. I found that the infamous Thermo Control Amplifier failure mode can be tested by shorting the two blue wires on the female connector on the outside of the evaporator box. Disconnect the connector from the wires that run into the box, with the red, white and black wires. If your clutch is not engaged, short the wires and see if the clutch engages. Good chance this indicates that it is indeed the thermo control amplifier that is defective. At least this might keep some from replacing this very difficult to replace part if it is not indeed the issue. Would be interested on input on this from others.  

I've been following this thread for quite some time until I could come up with the money to fix my A/C in my 2000 xterra.  I finally had to replace the timing belt and water pump last weekend and figured we would address the A/C also.  Mine was the high pressure hose.

If you look near the radiator, where the rigid hose is crimped onto the rubber/flexible hose you may see oil or drainage.  That's what I had.  It cost me an additional $250 or 300 to replace the high pressure hose and recharge the system at the dealership.  It's been good since...knock on wood.

Mine was whistling out of the center vents before I got it fixed.  If you guys can find someone to test the system they will tell you what's wrong so you can save up for it and replace.  I had a guy diagnose it for 25 bucks - a lot cheaper than the dealer's 100.  

OK I hate to dig up an old thread but it turned up in a Google search.

I have a 2002 Xterra. A/C worked fine for 4 years, and two months ago it stopped cooling (just blew hot air). I used the refrigerant with the leak detection to check for leaks. It also identified the HP hose, right at the fitting. Funny how thatr's also popular. I got a new hose from AutoZone (Oreilly will match if you don't have one nearby) for about $70. Pulled a vacuum on the system. Recharged it with almost 4 cans of refrigerant. Ran like a champ. Fast forward to today. Blows hot air again. Leaks again, from what looks like the fitting at the same spot. There's no way the system gets high enough to fail the fitting. Well, not a normal hose with a normal crimp. I'm going to check with a blacklight to be sure there is no overspray hitting that point from something else (compressor, other fittings?). Anyone see this?  

The Discharge Line leaking on the 3.3 v6s is a defect.. I have replaced mine and everyone I know with a nissan has also done this. When I replaced mine I noticed that a resonator for the intake sits right above it and could be the cause. I removed that since and have had no problems since. Minus the temperature amplifier thing.  

I have experienced this same issue for the past 2 years and have spent hundreds of dollars as well on my Nissan Xterra A/C.  After reading these posts, I went and bought the Thermo Control Amplifier part and insisted (inspite of yet another mechanics suggestions) that he simply replace the part.   A month has gone by and I am not having any further problems with the A/C. It works great!  The part cost $40 at a Nissan dealership and the labor was $250.  So after close to $1000 I finally have an A/C that works.
I think this is completely UNFAIR that I had to diagnose the problem and Nissan did not help.  With as many people that have posted this problem, I believe we all have a case for a recall on this part.  I have already created a claim with Nissan and if some of you would take the time to call 1-800-Nissan-1 and tell them about your experience, we may get this taken care of.  KEEP YOUR RECEIPTS!
You can also email:  nnaconsumeraffairs@nissan-usa.com to make a claim.  

So glad I googled this problem!  I had the same issue that everyone else has described.  The noise coming from the center air console.  Warm or hot air.  2000 XTerra SE.

I took it to get a air system check and was told that I would have to replace the high pressure hose, drier, and get everything redone.  Grand total would be $800.  I left because it seemed to be a lot.  I was looking at the cost of a drier at autozone and it is less than 1/3 the part cost quoted.

So I am thinking about replacing both the high pressure hose and the thermal control amplifier.  Do you have to replace the drier as well?  I was told that you have to replace the drier whenever you replace the hose.

But I felt the entire time like I was getting the upsale because I was a female.  Some places don't give me that impression but this one did.....

Thanks for any input.      

I bought my Xterra new this year, one month ago, and while driving a ten hour trip the air stopped flowing cold. Did that intermittenly during the next week until my appt at the dealership, Gettel, in Sarasota, FL. While in the waiting area two customers were talking about their Nissan air conditioning and had the same prob. Service Tech stated that he could not locate a problem since the air was currently working well. I asked him if Nissan was typically having air prob's since at the time of my visit, there happened to be three of us with the same problems. Although, he did not answer directly, he stated that typically when air conditioners go out its the high pressure hose loosing pressure but they could not do anything until they could feel the air blowing hot. If I wanted to pay, even though thirty days old now, I could have the hose replaced, but no guarantee that the air cond. would be repaired. I came home and found this site. Son of a Gun is all I can say. They now there are problems but do they recall the Nissan cars or fix the prob? Guess not. Thanks to all who posted with their suggestions and fixes. I hope I find my solution also.  

hi:  Have had the same problem with my son's 2000 xterra. replaced pressure hose from compressor to condensor which in his case was leaking and is very common with xterras. But later his a\c would work sometimes and other times it wouldn't, but the differents between now and before is that the freon level was full. I work at a auto shop and have access to all-data information on-line. Checking wiring diagrams I found that on the dryer tank in front of the radiator on the passenger side there is a triple-pressure switch that screws into the top of the tank next to the line connection. It has 4 wires at it's connection, two of it's wires make a connection when the pressure is above above 50lbs psi. The problem is that the switch internaly doesn't make the connection so that the (ecm or computor) doesn't turn the compressor on . Replace the pressure switch and everything works fine. Switch is sold at dealership and parts houses (note freon will need to be evac. first to install unit and then recharged)  good luck :  Cecil  

Greetings one and all, my name is Kaycie, and I am also a not-so-proud owner of the infamous 2000 Xterra A/C gremlin.  (this is reminding me of a support group) As I was going through the posts, recognizing symptoms as well as frustration, nodding my head in agreement, I stumbled across one posting that seemed unusually well written.  Lo and behold, it was my very own post from a year ago.  Well, last year I fell for the "High Pressure Hose" trap and becuase the A/C worked, I thought my dealership was surley full of geniuses.  Well, as I sit here today, in a pool of my own sweat and tears from driving home for the third day in a car that is mocking me with its hot breath, and exactly 1 month past the one year warranty, I am feeling more like Charlie Brown to Nissan's Lucy. I thought I would post the followup 1) as therapy, and 2)to tell you not to fall for the gleaming white vison of cool cool air that the HPH will give albeit only temporary relief.  So while I am sure they will sink me for another HPH, I am going to ask them to replace this Thermo Control Amp thingy while they have it.  

PS:  What is this I read about a driver's side window problem on the X? Do I have another gem to look forward to?  

Hey guys, first time poster.
My a/c puts out hot air. When I turn on the a/c it sounds like there is a "hissing" sound coming from the vent. So this tells me I might have a leak, right? So I bought one of those leak test kits and tried to connect the pressure gage on the low-side hose. HOWEVER, I see a blue AND green cap really close to each other.
I've taken off both caps and tried to attach the gage with no luck.
1. Which cap is the low-side that connects from the compressor to the evaporator?
2. Could this still be a thermo control amp issue?

I've attached a pic of the 2 nozzles in question.

I'm really hot since summer is starting to heat up here in Sac.

Thanks
 

The blue cap is your low side fitting  

Thank you, Thank You , Thank You for posting this topic. Any thanks to everyone for make fantastic suggestions to the A/C problems. I have a 2002 Nissan Xterra and this past winter I noticed that my A/C starting blowing warm air intermittently.  I was able to live with it thru the spring season with milder temps. However when summer hit we had 90-100 temps and I really need my A/C.  The blower has always been strong and worked great. However, it would mostly blow warm air and very rarely blow cool air. It never seemed to be ice cool though.  While getting my tires replaced I had my mechanic check the system out for any problems with my A/C. They charged me $150 to take a look, add a small amount of freon and inject a die to see if there was any leaks.  I saw your posts before taking my car to the mechanic. And I told them that it might need a new thermal control amplifier based on what I read on the net.  They ofcourse thought I was just another stupid crazy female that didn't know what I was talking about.  So after paying the bill, my husband decided to take on the challenge.  He bought me a new thermal control amplifier for $44 from the local Nissan dealer. The part # is (27675-9Z000)They call it the Controller Assy.  And after a couple hours of swear words, he got the glove box off and the black box case around the evaporator core unscrewed to find a little red plastic piece with wires handing off. This is the Controller Assy , aka thermal control amplifier.  My car required the 3 prong one.  Wow!  this little thing fixed the problem and my air blows ice cold with no problems since!!!!!  So save yourself tons of $$$$$$ and buy this $44 part. You may say a few swear word to get into the black box behind your glove box, but it's worth it.  I guess it show all those mechanics out there that women are not so stupid after all when it comes to finding a way to fix their vehicles!!!!  

I started having this problem with my 2007 Nissan Pathfinder.  No problems last year but this summer is different.  Have had my car to the dealership for the 3rd and was getting the run around. Left today after 3rd trip to have them tell me nothing was wrong and the problem started again drove right back down there and they finally agreed there was a problem.  They are ordering me a new panel so once the parts come in we will see if it fixes the issue.

Also,  Had a friend that bought a 2008 Maxima and was having this problem from day 1.  Looks like Nissan needs a RECALL!!!