A.c.not cooling at times?

Could be freon level, or auxiliary fan for the condenser coil in the front, or electrical power to the compressor clutch or the relays in between.

expansion valve..

I had similar problems 2 times with the automatic heat / AC module.
I suppose your system is automatic too.

First time the commands were working erratically acting weird. Sometimes was heating at full capacity blowing heads off. At other times it was not starting at all.
The whole module had to be replaced.

Second time if the car stayed in the sun the AC was heating, after starting the engine and cooling started only after achieving greater speeds (above ~60km/h). Whenever the speed decreased the system began to heat again eventually. It turned out that the engine cooling fan was broken and had to be replaced. That fan cools both the engine radiator and the AC radiator. If it is faulty your engine might be at risk of overheating at low speeds.

Your ac system is most likely low on freon, or the cooling fan is not working.
When you turn on the ac the cooling fan should stay on.
If it stays on then you are low on freon.

YOUR AIR CONDITIONER PUT LOAD ON ENGINE CHECK TO MAKE SURE RADIATOR COOLING FAN RUNNING BECAUSE IT HELPS TO KEEP THE ENGINE COOL AND AC CONDENSOR COOL FAN NEED TO BE RUNNING IF NOT CHECK COOLING FAN FUSE OR RELAY.

The cooling fan is required to operate when the engine temperature rises above the maximum operating temperature threshold.
After the car is started, it will usually take some time for this temperature to be reached.
Ensure fan runs when fan control temperature sensor switch demands.

It sounds like the ac compressor is building up to much head pressure.Check the cooling fans to see if they come on when the ac is turned on.The cooling fan should come on when the ac is turned on.This keeps the head pressure down so the freon keeps cool enough to cool the vehicle.Check the cooling fan,or fans to see if they are working when the ac is on,let me know if I can help you any more.

Sounds like the cooling fan motor,or motors,are not working.Check the relays,and fuses for the cooling fans.If the ac is on,look to see if the cooling fan,or fans come on.If they do ,then most likely have an enternal ac system problem.The expansion valve is the most likely problem,or possible,the dryer.Have the ac system checked to see if it is low,or if the low side is going into a vacuum,if it is going into a vacuum,replace the expansion valve.First check to see if the cooling fans are working with ac on.If I can help,let me know.>>>[email protected]

Run engine from cool, with rad cap off & heater on heat (not AC) and watch for circulation through rad when engine reaches normal operating temperature. Rev engine slightly from time to time for a couple of seconds, to increase flow & help bleed air out of system. Let it run for a while, and watch for increased flow in rad 2 or 3 times. Probably see air bubbles at same time.Hot coolant from engine comes in top, and back out bottom to engine after cooling in rad. The increased flow in rad ,indicates thermostat is opening & circulating cooler liquid back into engine. After 2 or 3 times put cap back on & fill return bottle only to line specified as warm/hot engine level.

could be a relay or fuse or maybe an ignition prob. seen that before