My a/c is blowin hot air ..

The most probable cause is loss of gas. Check on the outside unit. Feel the pipes, one of them should be very hot, the other very cold. If not, get a service guy to replenish the gas and check for leaks.

Sounds like your heater blend doors aren't adjusting from cold to heat. If you google "blend doors" you can read about them. They are usually pretty hard to get to, the dash needs to come out. Hope this helps! Jonathan Lavezzo www.lavezzoconstruction.com

The first thing to do would be go to your local auto parts store and buy an air conditioning recharge kit. Provided your vehicle isn't too old, they sell recharge kits that require no tools.

If their is a leak anywhere while you recharge, you will know.

Try recharging the air conditioning first, it is very simple and the kits come with simple instructions.

If there are no leaks, your A\C will blow cold air again. As for the pressure, if it continues to slightly blow air you may be looking at a new air compressor unit or a vaccum line. A new unit will run you anywhere from $200-$2000 dollars plus labor depending on the vehicle.

If the recharge works, at least you will have slightly blowing cold air rather than hot and you can continue that way until the unit fails.

needs to replace the heater core

Please consider this as an serious issue. CHECK OUT UR AC CONDENSOR. GAS NEED to be REFILLED FOR THAT.CHECK OUT UR VENTILATION ALSO.

Either the thermostat is bad on the engine, or the selenoid that acuates the damper that allows cold air or hot air to enter the vehichle is bad. What car is this on? Some newer cars have the electronic thermostats that control cabin temperature, this may also be bad.

jtg

I have the same issue. I found that the plastic gear under the stearing wheel is stripped and it automatically rotates to the cold function. Seems like a simple fix but i went to nissan today and of course they want to sell me the whole heater box. its easily accessable to check it out. You can see where the cable comes from your hot/cold knob.

AC COMPRESSOR ON HONDA USE A SINGLE WIRE IT COULD HAVE BEEN UN PLUGED DURING TIMING BELT CHANGE CHECK IT OUT

hi there, im thinking egr valve because of loss of power and erratic idle or the idle air control valve because it also too has the same effect