I have a 2001 v6 Manual that blows hot air. I've found a lot of articles, but lacking the specifics, so I wanted to ask here.

So firstly, I tried filling up with refrigerant. Once I filled it, the line beneath the filler hole got extremely cold. This tells me that the compressor is working. But still blowing hot air.

What else could I easily check/replace before resorting to a dealership diagnostic?

 

guess its off to the dealer. . .

 

I had a similar problem with mine it always blew hot air except when it was set on full blast. I had to replace a $5 part under glove box. I cant remember what it was called though

 

Huh? heres an air conditioning primer.

Starting at the compressor, engine turns compressor which compresses refrigerant (its a gas at that point) and creates a really hot, high pressure gas. That high pressure gas goes into the condensor (a heat exchanger) located forward of the radiator. there the really hot compressed gas cools off from 160 F or so, depending on how hot is is outside. As it cools, that gas condenses to a liquid. Now it travels thru a small A/C hose (called the liquid line, the one with the fill port in it) towards the dash panel of the car. When it gets to the dash panel interface it goes thru a metering device (old days = an fixed oriface tube, more modern cars a thermostatic expansion valve. ) The metering device only lets a little bit of refrigerant thru at a time. After it passes thru the metering device, the pressure drops considerably, so much that the liquid refrigerant boils to a gas. The transition from liquid to gas requires heat, and this makes the gas really cold, generally down to the near freezing, lets say 35 degrees. This transition occurs in the evaporator core. Air is passed over this heat exchanger cooling it down. After the refrigerant leaves the evap core its a warm gas.. it goes to a bottle called an accumulator (or dryer) where there is a dessicant there to dryout all water vapor from the refrigerant system.

Couple of notes: You don't want the evap core to get too cold. When this happens in high humidity areas, the core will actually ice up and shut off ALL the flow of inside air.

Max A/C setting is awesome. In this setting only one thing is happening. There is a small door inside the HVAC case.. in one setting the door grabs outside air, in the other setting the door recirculates air inside the passenger compartment. Its much easier to cool inside air that is at say 80 deg, then it is to cool down outside air (say 110 degrees here in Vegas) That means in the max setting your system works LESS to perform. You are not saving gas by keeping your system in normal A/C mode, just the opposite.

to the original posting author. When you plugged in a can of refrigerant to the liquid line it went in as liquid and immediately evaporated, causing the line to get cold. This is a one time deal, and frankly probably means you were filling a totally empty system. I suspect there is a leak somewhere. In normal operations that line doesn't stay cold.

The amount of refrigerant is a big deal. Additionally the A/C compressor has very high tolerances. Lubrication for this system comes from refrigerant oil migrating throughout the entire cycle. Too little oil = bad for compressor durability. too much oil is bad for the refrigerant cycle. Oil is carefully measured and added to the system when the vehicle is first built. Problems can occur with the quantity of oil after HVAC repairs. Additionally the amount of refrigerant matters. Too much = poor cooling. Too little = poor cooling. If you are not sure its probably better to stick with a professional.

Zip (former HVAC design engineer for an unnamed automotive OEM)

 

One more update. The aircondition system is sorta independent of the heater system. All air inside your vehicle goes thru the evaporator core. In the winter the refrigerant stuff is shut off, the compressor is not running.

Engine coolant always runs thru the heater core, all year long. There is a door that bypasses air thru the heater core as required, generally used in the winter when its cold outside. If there is something wrong with your heater system and you are routing air across the heater core that will totally overwhelm the A/C cooling system.

In other words, its possible to have a fully functioning refrigerant cooling cycle, but accidentally dumping heat off the heater into the system. The door to the heater should be fully shut in the summer when its hot outside.

 

Good info.