We replaced the compressor and cooling radiator under the dash. Now it cools but not enough. Mechanic put in more freon, but it didn't help.

The basics - - low on freon, radiator fan not working all the time, compressor clutch, an electrical problem that involves the ac clutch, and a problem with the blend door under the dash.
If the compressor is coming on and off, that would involve some of the issues listed above.

The radiator fan should turn on when the a/c clutch engages as this is designed to increase the cooling of the engine as the a/c increases the engine loading. But the compressor clutch should stay engaged as long as there is need for cooling, and disengage/re-engage as the temperature control calls for cool air. The radiator fan will shut off IF the engine temperature is cool enough to do so, as it is regulated by heat, as well as the A/c override.

If your air conditioning is not cooling the car and the clutch is simply disengaging prematurely, have the temperature control and relay checked for proper operation. Also have the refrigerant level checked to assure there is adequate refrigerant in the system and no leaks. My first bet would be the relay or the thermostatic temperature control under the dash.

sounds like unproper ac evacuation before charging the freon to your ac system. do a proper evacuetion to the system check the ac compressor oil charge the proper freon & amount check the vehicle tag for the amount of freon under the wood close to the radiator

Hello,
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Let me explain in layman's terms how the air conditioning (AC) system works and what could be happening to your car.

Like your body, the air conditioning compressor is the heart of the AC system, and Freon is the blood. The compressor pumps Freon throughout the AC system, either the older type R12 which costs as much as gold it seems these days, or the new environmentally-friendly R134A Freon. This Freon is a gas and liquid combination that is compressed and circulated throughout the air conditioning system. The compressed Freon is pushed through the system under pressure and is passed through different sized metal and rubber hoses and a special valve called an expansion valve that cause the gas to expand and contract.

This expansion and contraction makes the Freon gas very cold. This cold gas makes its way via metal lines into the dash area of your vehicle to the evaporator core. This evaporator core is like a small radiator, except it has cold Freon circulating inside and not hot antifreeze. A small fan (the AC blower fan which you control from the control panel on the dash) sits in front of the evaporator core and blows air across this cold evaporator and then through the vents inside your vehicle.

The other objective of the air conditioning system is to remove the heat from inside the cab of the vehicle. This heat is removed by the Freon with the help of the AC condenser located at the front of the car (usually in front of the radiator). The Freon coming back from the evaporator carries the heat from the cab to the condenser via rubber and metal hoses. Just like your radiator, the condenser is lightweight aluminum with many internal winding coils.
The Freon travels through these coils, and in between these coils are small slits or fins that the Freon is forced through. The condenser will have an electric cooling fan mounted in front or behind it to push or pull air through these fins to remove the heat from the Freon. Some vehicles still use the old fashioned fan blade driven by the engine to pull air across the radiator and the condenser.
Now I know that is just a tidbit of information on how the air conditioning system works, and it is very general, but I wanted you to know what to look for to give you insight as to what might be happening with your vehicle.
A few causes of low cooling efficiency or no cooling at all at idle are:

Lack of air flow across the condenser. Make sure the electric cooling fan motor near the condenser is coming on, or in models that are equipped with a fan blade make sure this fan is turning and is turning very fast.

Low Freon levels. Freon level and pressure should be checked by your certified air conditioning mechanic.

Overheating. If the engine is running hot or overheating, it can have a noticeable negative affect on the air conditioning system. Some cars have two electric cooling fans, one for the air conditioning condenser and the other for the radiator. Make sure they are both working properly. Usually at idle on a hot day with the AC on both fans will be on.

When the vehicle is traveling at freeway speeds, the compressor is pumping the Freon throughout the system much faster and harder than at idle. There is a dramatic increase in air flow across the condenser due to 55 mph winds, and the engine is usually operating at a cooler, more efficient temperature as well, thus allowing the air conditioning system to operate efficiently.
Note: An air conditioning system that is somewhat low on Freon can still feel comfortable at freeway speeds due to the added air flow across the condenser which can overcome the ill effects of slightly low Freon. Periodic air conditioning performance checks by your mechanic are the best way to keep the system in great shape.

Hope this helps.

Goodluck

you need to put a pressure gauge on the freon input nozzle and see how much freon is already in your system You are probably getting no cooling because the clutch on the front of the A/C compressor is broken, or the switch on the dash is not opening the vents inside correctly. Putting more freon into an already full system can have unpleasant results. So if when checking the gauge, the freon levels are ok, next, run the car, and look at the front of the A/C compressor.see if the clutch clicks in and out as the A/C is turned on/off. If the clutch free-spins all the time it needs to be replaced, or if its silent completely, the wiring to the A/C needs to be checked. If the clutch is ok, head under the dash ad listen for the vent doors opening and closing as you cycle the A/C on/off. If you can't hear them, a vacuum pipe or electrical connection/A/C switch is to blame.

No way he replaced everything and have a leak unless he didnt put it together correctly. Suggest contacting the manager from the establishment and if he can straighten it out get your money and go to a dealer. If they cant help you file with the better business bureau.
That being said 3 high leak areas are the condenser by the radiator (looks like a small radiator) , the evaporater (in the dash to make the car cool) and the compressor mounted to the motor. With dye in the system he should have no issue charging it and looking for leaks.

If you tried using a refrigeration "sealing" product before changing out the compressor, you most likely do need to replace the expansion valve.

The valve "flutters" open/close/open/close/etc/etc when in operation. The purpose is to allow the compessor to build up enough pressure to change the freon to a gaseous state. Once you put in the sealer, the valve becomes plugged with the product and cannot seat completely. After this happens, you never get a full phase change because the pressure cannot build up enough. You will experience reduced cooling. Change the Exp. valve and you'll be set. In the future, it is not advisable to ever use the sealer products as this can cause damage to other system parts, and especially the recovery units at the shop.

put gauges on it first to see if it has enough freon to make compressor come on

You can buy a can or,refil kit of R-134-A at walmart however only put the freon in on the low side (read the directions) if the freon gas will not go in; run an 18 gauge wire from the battery to the compressor clutch switch to run the compressor if the freon gas still won't go in it must be evacuated and, recharged by a shop. only put in enough freon to get the system cold any more than that and, you will lose cooling again (over charge)

a refurbished compressor should be fine and will be cheaper than new, your should also replace the orfice tube (expansion), and the dryer, and the seals at the connection points.