05 MDX isn't blowing Cold Air! New freon .75 lbs was put in, ran for 1 day and went back to blowing hot again. My pressure was up to 500, freon was taken out and put back in with 2 more cans! Water was splashed on the front near the radiator to cool off the car. Got cold almost instantly. Ran for 3 days now back to hot air!! Help!!

You could possibly have a blocked orifice tube or a low-pressure situation within the system. Sadly though, a high-pressure situation could cause the problems you're having as well.
Over-charging a system with freon can make the sensors and compressor freak out, thus, causing blowing cold one minute, then giving up the ghost the next when the compressor tries to cycle again. Most systems these days sense the high pressure and shut the compressor down to keep it from over-powering itself, and the lines.
Take it to a competent shop and have it tested or stop by a local parts store and purchase a pressure gauge for your A/C.

Could be low on freon, have a pro check it out unless you have the proper gauges. Or could be the low pressure switch is not working. System must be tested for leaks first then pressure checked. DO NOT just add more freon from a can you could damage the compressor or parts of the a.c.

Possible heater core poss. thermostat ck. both heater hoses at fire wall 1 hot 1 cold its the core ck pass side floor wet its the core Maybe head gasket

I would and sometimes you have to hold the recharge hose down on the fitting with some pressure to get it to take the R134.

Hi, if you have full pressure (40-50 PSI on low pressure side with engine running A/C set to maximum and blowing) you have enough pressure, but there is air in the system which degrades the refrigerant leading to no cold air. To remedy this, you must completely discarge the system and refil with new R134a which has the compressor/system oil added to it.
To discharge the system, shut off motor, attach your filler hose to low pressure valve and allow system to drain. (squeeze handle if you have that type filler hose) Allow it to drain until no sound of escaping air is present. Be careful not to have the end of hose facing you or others, wear gloves and have some shop rags laid down, pointing nozzle toward rags, that stuff can damage paint and skin and may be cold when escaping. After system has completely drained, start the refil process with engine running, A/C on maximum, blower on full. After about 1/2 of the first can of R134a or 1 full can, your compressor should kick on. Continue refilling with 3-4 cans total (about 3 LBS total) until you have a reading of 45 or so PSI. After each can, allow refrigerent to cycle through the system about 3 minutes to obtain an accuret pressure reading. Pressure is relavent to outside temperature also, optimumly the ambient air temp. outside vehicle should be between 72 and 80 degrees F. for proper reading. That should get you blowing cold air again!
Please rate this answer! Thanks, Mike

if you let it sit for a few hours will it get cold again? if so you may have a problem with the evaporator icing up. but that is only true if it will get cold after it sets and thaws.that would mean the low pressure switch is stuck closed. if that's is not it please get the pressure readings and post them .we will be better able to help. you should have at least 90 lbs static pressure at 75 degrees out side temp.if the pressure is lower or less than 50lbs. with the engine off .the freon has leaked out.if it took years to leak out just put 1 lbs of freon back in. they now sale freon with the low pressure Gage built on the can .so you will know if the level is low. with the engine running you should see about 25 psi on the low side .it will change as the compressor cycles

did you touch any wiring ??possibly a loose connection? a/c pump clutch???,anyway you wont be spending any money putting it right........good.

the air mix door may be stuck or broke does it blow cold air on hot days after the freon is replaced and for how long it may be leaking back out ?? it may be an door acutator as well or linkage

If putting freon in made the a/c stay cold for 4 days then you need to have the system checked for a leak

I BROUGHT A 94 SIERRA, THAT WAS IN A ACCIDENT. THE DOOR WON'T LINE UP, EVEN WHEN I ADJUST THE BOLTS. IS THERE ANY OTHER WAY THAT I CAN LINE IT UP?