My air conditioner will cool for about 5 minutes then starts blowing warm air. i have replaced orphus tube and all filters. when it starts blowing warm air i get a wet dirt smell in the cab. is it my evaporator core or what?

Sounds like a fan clutch problem or ??
Can you drive it and when it quits cooling check and see if the compressor is still running ?

If after a few minutes it is still warm to hot air, try recharging the cooling system. Parts stores sell kits with instructions on how to do this.

you really need to service an air conditioner with all the professional tools what are the pressures on the low side and the high side ? what coolant did you put in ? and how much ? r134a will only work if its done right too much and it will blow warm too little and the same thing you need the right amount did you change the receiver drier ? its a moisture filter it only works for about 5 years or once it gets moisture in it then its no good and needs to be changed also most gm's use an orifice tube filter in the high side line it too needs to be checked and cleaned or replaced . if the gauge needles are jumping around the compressor is bad . if the pressure is high on the low or high side over specs = no cold air . hope this helps

The front expansion valve is bad,have it replaced to fix the problem.If this was at all helpful,please rate,thank you.

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced.
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is worm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest to flush the heater core.

It is most probably the problem with blend door or blend door actuator. But just in case I would suggest to follow the entire procedure:

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is warm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest flushing the heater core.

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced.
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is warm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest flushing the heater core.

Follow the small line from the evap. core to the condenser.It is in that line

could be many things such as a leak in the a/c system, blend door/motor, clogged orphus tube, or an electrical problem in the a/c circut- i usually recomend that a/c work be handled by the professionals due to health hazards and most people don't have the right tools to do the job.

I have a 2002 Jeep Liberty and after driving for about 30 minutes the air conditioner would start to blow hot air. The air conditioner clutch was sticking. I could hit the clutch and it would kick in and start to work. I went to Advance Auto and purchased a big spray can of electric motor cleaner and a big spray can of WD-40. I soaked the clutch with the electric motor cleaner, used the whole can, then soaked it with half a can of WD-40. The clutch has worked perfecty ever since.