I bought my second monte carlo, and one of my only issues with it is that the AC wont work. there is no temperature change if i turn it on or off. the compressor clutch is engaging, i swapped the coolant temperature sensor because the cooling fans will not turn on when i turn on the AC, but they will turn on when the engine temp gets too high. the system seems to have sufficient enough pressure to at least be felt at all through the vents. Also i replaced the cabin air filter, because it looked like someone threw the old one in a trash compactor. I am not very well versed in AC so any help would be appreciated

 

You may need to re charge the system, I just did mine last week. Picked up the kit at my local wal mart and you hook it up and turn the car on with the ac on high then add the refrigerant to the system and let it run for about 15 minutes. If you do this just remember do not puncture the can with the needle (the part that connects to the can you turn the valve and the needle comes down and punctures the can and allows the freon to come out through the valve into the system) until it is hooked up and you are ready cause it will just start blowing out the sides and you will lose your freon.

Total time takes about 18 minutes and you should have nice cold air, assuming that your pump and condensor and clutch are all working and no major holes in any of the coolant lines for the ac. The black valve cap is located behind the engine on the firewall on the silver ac lines approx in the middle but closer to the drivers side of the car.

 

i charged it already, says it has around 35psi in the line. should i check the pressure while the ac is on or off? because im reading around 35psi with it off, but its lower when it is on, right below the good to go line on the very generic gauge that comes with the bottle, that probably is not too accurate. My concern is that i don't want to keep dumping refrigerant in it and mess it up even worse.

the thing im most curious about is that the cooling fans do not turn on when i turn on the ac, could that be caused by low pressure in the system? Because they do turn on when the engine gets too hot, and i did replace the coolant temp sensor.

 

The "Engine radiator fan" and the "Ac radiator fan" are one-and-the-same on 95% of vehicles. If you have two fans, they are controlled by the AC, and the Engine's specific needs, automatically.
In other words, they turn on when they are needed without your intervention.


even if the car is dead cold. when you turn the A/C on(compressor switch on) the fan should be on as well even if there is no gas in the system.

if the fan does not turn then either the condenser fan relay is bad, fan fuse is blown, fan is bad(if neither the A/C or hot temps can make it run) or there is a short circuit somewhere.

to know if the fan is good. remove battery terminals. get 2 cables and jump the FAN plug NOT the one going to the electrical wiring, only the one that goes directly to the fan/s
and jump it straight from battery. keep hand and anything away from fan. if the fan is good it will spin. it doesn't matter which is positive or negative all it will do is to make the fan spin either clockwise or counterclockwise. if the fan spins start looking for a bad relay or switch / fuse, or bad cable.

If you have charged the system and there is no cold air coming out you may need a door blend actuator, you can find them at rock auto.com for under $40 but don't change until you are sure this is what is needed, but it is part of the system that allows the air to flow through your car.

Do you get hot air when you turn up the heat? if not then it may be the system door actuator itself in the dash that is your problem not allowing the air to change temperatures

 

The fans are good, the engine getting too hot turns them on, and I've seen them run. But they won't run if I turn on the ac. It does blow heat, so thats good. The door blend actuator or the condenser fan relay are my next things to check in that case.

 

Here's a quick test to see if the condensor is not being cooled enough. Get a garden hose and spray the condensor with water without stopping for about 30 seconds to a minute. After that, run to the car and see if the AC is blowing any cold air.

Small tube passages that are designed to make the condenser more efficient also trap debris that cannot be thoroughly removed by flushing. Trapped debris will block condenser passages and restrict refrigerant flow, diminishing the overall heat transfer efficiency of the condenser.

 

Go inside an underground parking lot and turn on your A/C (if it works) and set temp to the hottest position. If the air is cooler than in vent position, the blend door is the problem.

If you need to turn temp **** at cold position to feel the A/C, the problem is related to the cooling system. Maybe there's rust deposit inside the heater core that reduce the coolant circulation.

another way to check the blend door motor is to disconnect it from the door lever and see if you can work the door by hand. If you can get heat by moc=ving the lever, the actuator is bad. The actuator is located under the center of the dash and is a little plastic box aboyt 4 inches by 4 inches. It has a wiring connection going to it. The blend door actuator is located under the glove box on the passenger side of the car, once you remove the kick panel and glove box it is on the left connected to the center pillar of the dash, it is held on by 3 screws and an electrical connector

Hope that helps and best of luck

 

I'll check this all out when I have time off tomorrow, thanks! I'll see how it goes

 

One other issue I can throw into this, you may have a bad actuator or a control to the actuator that is preventing a flap on the HVAC module from adjusting and allowing the A/C to blow into the cab.
If you are seeing water coming from the condensate drain, then you know the coils are freezing. In all honesty, if the compressor is engaging, the system "should" be working (compressor will NOT kick on if it's too low on freon).

Sounds corny, but check your fuses and relays.

 

i know it sounds corny but i think you are right, a fuse or a relay is probably the issue. the only thing i can see wrong, other than no cold air, is that the cooling fans wont turn on when i turn on the ac, but they will turn on if the engine runs too hot. i can see the clutch engage and disengage if i turn it on and off. ill pay attention and see if i can run the compressor and see if any water is coming out of the drain though, thats a good idea. a dirty condenser might also have something to do with it as well so ill see if it needs to be cleaned. when i adjust the temperature in the car to hottest it blows hot, and on the lowest it blows outside temperature. I know for a fact the temperature control works, but if there is an actuator that lets in/blocks off the cold air from the ac i would believe that could also be an issue.