Air blows cold then all of a sudden blows hot then starts blowing cold again. Freon pressure is perfect. Is compressor going out or is there a sensor switch somewhere? mileage 206000

 

Do you hear the compressor clutch engaging and spinning when this happens?

It could be the compressor/clutch

or a blend door malfunction.

Not sure if your blend door is vacuum or electrically controlled, but look under the dash and engine area foor damaged vacuum hoses.

 

Everything sounds to be operating normal. What is a blend door vacum?

 

The blend door is mounted within your airbox under the dashboard that either opens to allow the heat off the heatercore to enter the vents, or closes too allow the A/C to work.

Typically you can see the blend door actuator by looking underneith the center dash area. When you turn the temp setting hot or cold, you will see it move.

 

Sound like the control head problem, it's electronic control head, no vacuum to it. I've seen this symptom before, kinda intermmitent depending on how long the a/c is running, when first turned on, it "run time" is longer before it's cut out, then the "run time" is getting shorter as of the circuit board (on control head) gets warmer/hotter, sometime when it happens(blowing hot air) try to press on the control head's face and see if the cool air air comes back on. This's only happens when you are in park/stopped.

If it's only happen when you are driving and the RPM is higher than 3K, then it's another story.

 

It happens when driving and or stopped idleing. It appears to happen more often in the heat of the day. I can't say it happens at all in the mornings.

Its seems to be cycling okay, just that when it cycles off it stays off too long.

 

so... when it's not cycling, does the a/c switch lighted?, if it's does, I think the control head is the problem, try to press on the control face and see what happen.