This 2001 Nissan Xterra came in with a complaint that the a/c does not cool very well. The customer said that it might cool for a little while but then it will stop. I checked the vehicle and the compressor was coming on and the air was cool but not cold. These vehicles are prone to having the thermistor assemblies fail so I wanted to get to the connector for testing. You can see it without removing the glove box but I find it easier and if it is faulty the glove box has to be removed.
There are two screws along the lower edge of the glove box assembly. There are four that have to be removed once the glove box door is opened. One in each corner and two at the latch bracket.
I saw that this vehicle has a cabin air filter so I decided to take a quick look at it. Wow, this thing is plugged up. I decided I had better clean this up be fore doing any more testing. I used and combination of a shop vac, an air hose and a long phillips headed screw driver to dig all of this out.
The only reason this thing was blowing any air is that Nissan designed some bypass ports into the filters.
There sure is a big difference between the old and new filters. Replacing the filters actually fixed the customers problem. What was happening is that the system would come on normally but because the thermistor air flow was being blocked by the dirty cabin air filters, it would turn the compressor off for a long time and the cooling process would stop.
The new cabin air filters installed. Sorry, I missed getting, the retaining clip at the bottom of the lower filter assembly, in the picture.
For more information on testing the thermistor or to see how a unit without a cabin air filter looks please click here.