It's frustrating, the summer is here, and my AC decided to take vacations.

Here's the story:

It had a big rubbed hose leak (Aftermarket PS hose rubbed the aluminum line until it leaked), the line was weld and installed again.

The AC worked great during that day, but on the next days the AC started "cutting" apparently not the compressor, but just the cold air "supply".

The tech told me to replace the Expansion valve and the dryer, and so I did, same result, only hot air.

Then he told me that the compressor needed to be replaced, because it was "misteriously" damaged.

Taken into account that since I've had the car 3 years ago, I thought that the system needed the overhaul, so I went ahead and bought a used compressor.

And still, hot air.

They even changed the pressure valve inside the compressor, and nothing, same thing, hot air. They even pressure-wash cleaned the condenser panel.

After 5 used compressors and 2 expansion valves, and they don't have a clue of what could be wrong, and there are no more parts to replace...Except for the condenser panel and the tripple pressure switch.

When they check the LOW and HI PORTS the readings seem normal.

What could the issue be?

If someone has solved this before, please chime in, we're melting at 42 C (110 F) and the temp is going up.

 

Is the line holding pressure?

do u have some pics?

Read throughh the FSM. That will help u troubleshoot. The line coming into the compressor should be cold. if its not its either expansion valve or compressor.

If everyhting is withing spec, then the door that switches from cold air or hot air may be broken.

 

I'll check the cold/hot doors...Thanks!

 

If there are more suggestions/tips, are more than welcome.

 

Lets try some math here.

If they = your mechanic, then you should = find another one.

It's pretty simple, if the refrigerant cycle is working correctly, pressures are good and the suction line and evaporator are cold then you have an air flow/direction/control issue within the HVAC plenum.

 

It has been a nightmare, but I didn't want to bore every reader to death with the hurtful details. This is my 3rd tech, they all seem to be replacing parts as if this is a GUESS GAME at my expense (I've gone thru 5 USED compressors in case I forgot to mention).

Everything seems normal, as the AC should be shooting ice thru the vents, but "au contraire" . The line coming into the compressor it's fresh, but not cold.

That's why the first suggestin makes perfect sense...I've speed read the FSM as I am at work, at it describes the procedure to check all sensors and apparently this "cold/hot" door motor/lever/assembly.

However I was thinking of removing the glove box and try to see if I can see when this door switches hot to cold and viceversa...Is there a better/alternate to do this?

I will give it a try, and report back.

 

Does anyone know what readings should I have on both LOW & HI ports? Maybe what these techs think is normal, it's not.

 

The pressure readings are on page 33 of section HA of the 1998 Nissan Maxima service manual.

If you don't have the Nissan manual, you can get it here:
http://boredmder.com/FSMs/Nissan/Maxima/

The door you refer to is called the Air Mix Door. It is not behind the glove box. It is in the very center of the car in the big white box behind the radio. You cannot see the door itself, but you can see the motor and the arm that moves it.

This photo is looking in from the passenger side foot well. The plastic panel that covers the end of the ECU has been removed.



To see it move (assuming it does work), turn the ignition key to the ON position and move the temperature control from hot to cold.

 

Excellent, thanks!