AC is acting strange. Local repair cant pinpoint. When the outside temps get above 90 the cooling gets intermittent. Blows ice cold below 90. Radiator is clean and the fan is pulling air good. Something is making the refrigerant overheat and kicking the compressor in and out. Charge is good and no noise from compressor. Any ideas?

 

Does the radiator fan come on when you turn the A/C on? It should, bad fan switch.

 

Yeah fan comes on with AC.

 

If the head pressure (high side reading) is too high, the pressure switch might be cutting the AC clutch on/off. Or the pressure switch itself may be going bad.
Either way, you need to take some pressure readings when it's working and compare it to those above 90 degree readings.
Not sure about the pressure ranges on these systems, but I'm sure someone on this forum has them.
Above 90 degrees and high humidity, usually makes the system have to work extra hard and produces a lot of heat.

( an old school trick.Spraying a mist of water on the condensor will cool it and drop the head pressure. If it started to cool this way, we would then start to look for the cause of the excessive heat/pressure buildup.

 

Then you need a good A/C guy, not just a mechanic down the street.

 

I am new here.
I have been having a similar problem.

Seems if I 'trick' the temp control on the dash by turning it to 'warm', I SOMETIMES can get the air blowing cold again. And it blows REAL COLD, then after 20-30-40-60 minutes, it shuts down, blows ambient temp.

Parts store shows no part for the temp control on the dash, but they have a temp sensor in stock; I THINK there is one on the compressor, and one on the condenser. There is also an 'ambient temp' sensor in front of the radiator/condenser (I am pretty sure).

let me know if you figure it out before I do!!
Any help is appreciated.

 

Your problem sounds like it is the "blend door actuator". The heater core is always hot the knob on the dash controls the airflow over the core; MAX Cool air does not flow over the heater core "MAX Heat all air flow goes over the heater core. The door itself may be binding or the step motor that controls it is probably bad. I think I saw it in an Advance catalog, but for sure from GM.

 

Thanks for the replies. I cant trick it into anything. Only way it goes back to normal function is a temp drop. Then it blows so cold after a bit you have to drop the temp dial. As for the water spray. When it started doing it, I stopped by a wash bay and sprayed the radiators on low pressure thinking it may have dust buildup and not letting the gas cool. It came back to full function until it dried out. Fan is pulling good volume of air so the gas has to be getting to hot and causing the thermal protector on the compressor to kick it out. Is the thermal switch external or internal? Any ideas on what to change? I'm in the boonies. Not to many professionals round here just some that say they are. Will try to get some pressure readings cold and hot.
Rock Auto lists an A/C Refrigerant Pressure Sensor and an Ambient Air Temperature Sensor.

 

thanks for the tip, I will have to look at this again...

 

Rock Auto lists a Heater Blend Door Actuator for 32 bucks. My blend door seems to be working fine. I can feel the compressor kick in and out when mine is acting up.