2001 extended cab, I4, 139,000 mi, auto.

Ac blows cold when it wants and is intermittent?  I found this post and bought the tca as described and 30 minutes later the problem was fixed.  Thanks for the pics taken and for someone determining this problem.

A few years ago I took this to a regular ac technician and they could not find the issue and did not charge me (Very reputable business practice).  They recommended taking it to the dealer to troubleshoot further.  I took it to Nissan and 850.00 later, a charge of freon, evac, tca, and ac control unit (fan and temp controls buttons) and it worked for a few years but it acted up again.

It seems to fail after we have cooler weather in Florida for a while and you don't use the system for a while and then it starts working intermittently.

 Hi! Everyone   Well if you're reading this, you're probabaly having a/c problems. I owe a huge debt of thanks! to all who have posted before!!!!! I seldom participate in forums and absolutely had to express my appreciation. As i live in Florida, the approaching summer heat had me worried-----have had intermittent ac for about 6 months and no spare funds to shoot in the dark with repair shops and dealers. It was the Thermal Control Amplifier! After reading through forums, I believed that there was something to the TCA. Sometimes my AC would work just fine, but there was no rhyme or reason. Typically, it wouldn't work when I needed it the most. Anyway.....I employed the info from previous posts on how to replace. Very Accurate. I am NOT mechanically inclined and was able to do it. Just know that you will have potentially saved hundreds/thousands of dollars by replacing this $50 part. Oh.....get this. When I went to my Nissan dealer, I walked up to the parts guy and held the bad TCA. He returned immediately from stockroom without looking up part on computer or anything! Wow.... I guess they sell a few of those! Thanks again all!

Boatbuilder306 wrote: There is all sorts of info on the net about this Nissan THERMO CONTROL AMP OR AMPLIFIER (TCA) problem - Xterras and Frontiers, and probably Altimas and everything else. Everyone apparently has it, and if you haven't, you will. Many forums refer to this as a THERMAL control amp, so the information on the net is spread out all over the place. Strangely enough, all the Nissan mechanics want to flush your A/C system, recharge the freon, check your compressor, run die through the system and do all sorts of diagnostics to the tune of $500-$1000, and THEN they'll replace this $40 part after all else fails. The part no. is 27675-9Z000. It is located on AND inside the black evaporator box immediately behind the glove compartment. Remove several screws and the glove box comes off completely. Lay on the floor board and look up. Then remove three silver screws holding the evaporator box together. You can pry it apart gently and then TRY to reach the RED plug-like thingy sticking out of the LEFT SIDE of the radiator-like thingy inside the evaporator box. If you aren't careful, the box WILL crack. No big deal. There are several screws reportedly holding the back of the evaporator box together, but nobody seems to have been able to actually remove them, except for (as one forum poster remarked) a small child who worked for Cirque d'Soleil. Use small hands or long needlenose pliers to pull the RED plug-like sensor out and try to remember what it looked like sticking in -- turns out you can stick the replacement part anywhere in the same general vicinity -- if you get it back in the same spot it is entirely a fluke. This red thing connects to a white connector thing (which is mounted on the OUTSIDE of the evaporator box and PLAINLY visible even without removing the glove box) by some wires that fold over a small slot in the seam between the top and bottom halves of the box. The white connector is TRICKY -- it slides DOWN over a little notch/detente in the back, and if you haven't cracked the box trying to remove the red TCA inside, you'll probably crack it trying to slide this connector down. HOLD onto the box with your left hand and use pliers or something to firmly grasp the white connector and slide it down -- the prongs on the side of the connector do not hold this connector on -- ignore those. It shouldn't take more than 30 minutes to get to this point, and another 5 minutes to stick in the new part, add some glue to the crack you just made in the box, then about 5 more minutes to screw everything back together. My guess is that if you have an intermittent A/C problem with your Nissan vehicle (any model), it's this TCA part. I've thought of starting a web site selling nothing but these TCAs along with drawings of the repair process. Why Nissan hasn't recalled these vehicles and repaired the problem at no charge is really inexcusable.

UPDATE 5/23/11: It has been three years since I replaced this TCA and still blowing ice cold air. No problems at all.