need advice- a/c probs

Over the last week or so i noticed my A/C doing something weird.
When the temp outside gets around 90 and up the a/c doesnt get really cold like it should and takes it a long time to remotely get even a little cold, but when the temp is lower then that, it works perfect and everything like nothing is wrong.
Ive had many say it just needs to be charged but i wanted to get all of your opinions on that first.

 

Search google.... 'How A/C works'

It's hard to say....since it runs fine in the cooler temps but not-so-much in warmer temps.

The best thing you can do for now, is have the system checked for leaks and paticularly the evaporator core (if they can). Check for leaks BEFORE having it recharged. Charging the system without a 'leak' check is a waste of money because you'll lose all the freon they put in.

My mother-in-law had her (Grand Cherokee) system recharged a couple times in 2 years (no leak check). Had it checked for leaks later on and nothing showed up. In the process of having another problem fixed (radiator core),they discovered her evaptorator coil was leaking. I'm not sure how or if they can test for evap core leaks. The evap core are usually behind the dash somewhere and very expensive to replace.

Or, just wait it out. If you have a leak, depending on how slow it is - your system could function like that for a long time before it gets worse. Or - it could be the hot weather also. How long do you run the A/C at any given time? Is it only for a few minutes or do you run it for 15 minutes at a time?

 

i can run it from 15 mins to at least an hour on some days depending how hot it is.

yeah whats throwing me off is how it works fine in the some what cooler temps like nothing is wrong :/

 

It's hard to say....you might need a charge, but again - check for leaks. Freon doesn't just disappear. It's a sealed system. When you lose freon, the system doesn't work as effeciently.

If you do have a leak....depending on size.....it'll just progressively get worse and the a/c will progressively not work as well. But, that could be a year...?? You just don't know. It's up to you.....if you feel the need to spend the money and have the system checked or not.

Aside from that, I have no idea.

I'm experiencing the same type of weather here... 90+ lately. Today & tomorrow supposed to be 100. Too damn hot to enjoy summer!

 

At the higher temps there is a higher heat load on the system. Also, you will have more refrigerant flowing through the system. There is a receiver/dryer canister that should hold extra/reserve refrigerant for times when there is a high heat load. If your system is low on refrigerant then it is possible you don't have the reserve capacity. As systems age you may get a small pinhole crack in your condenser (heat exchanger rad in front of your engine radiator) or your compressor shaft seal may leak a little. Your system may therefore need to have refrigerant added. It is best to do this by filling the system to the exact specified weight of refrigerant. That means, completely discharging the system, pulling a total vacuum on it, and then filling with the correct weight of refrigerant. Don't just add some refrigerant until she blows colder. Low refrigerant may not be your problem.

Another possibility is that your condenser is dirty or its fins are all bent up and you are getting poor air flow over it. Look in through your front grill and see if your condenser is full of bugs or mud. Take a hose and clean it off.

 

thanks for the advice guys... I appreciate it. Im going to try to get into a friends shop to have it completely looked over before, like you said, spending money and wasting it. Ill let ya know the outcome in whats wrong with it and everything.

 

If its getting cold at all I'd say theres no leaks, bearing01 is half right , I'd look for dirty coil. if coil is dirty the system really struggles to meet the call for cool, & if really dirty what happens is the coil starts icing up further restricting air flow & the result is blowing hot air no cool....


Heres a brain twister for ya, in the world of refrigeration there is no such thing as "COLD" it is considered "ABSENCE OF HEAT. " true fact

 

Not really. More like "ABSENCE OF ENERGY". But I'll help twist your brain twister a little more.

Stating that an object contains heat is like saying that a ball on top of a hill contains work. The ball on top of the hill contains potential energy, not work. Letting the ball roll down the hill converts the ball's potential energy to kinetic energy. Another example is like saying that a gallon of gasoline contains X BTU's of heat. It doesn't. It contains a given amount of chemical energy that is released and transferred as heat if burned. A BTU is a unit of energy.

An object contains energy and heat flow is a means to transfer some of that objects energy to another object containing less energy. When two objects are in contact and one object has a lower temperature than the other, some of the energy of the hotter object flows into the cooler object by means of heat flow, until the cooler and hotter objects equalize to the same temperature.

When you feel cold it is because an object with lower internal energy that is uninsulated is able to draw energy in the form of heat away from your hand because of the temperature difference between your hand and the cooler object.

Take an insulated container of liquid and stir it up as fast as you can with a spoon using muscle energy. I've seen high speed blenders actually boil soup this way. The mechanical energy is transferred to the water to raise its temperature because it raised its internal energy. The turning of a spoon or blender blade does not add heat to the water. It transfers energy to the water. Some may think of it as an increase in thermal energy because the water had its temperature raised, but you only consider it to be "thermal" because you sensed a change in temperature, which was the effect of energy flow. But in a case where the water undergoes a phase change say from liquid to vapor then the water & vapor will remain at 212*F / 100*C until all liquid is transformed to steam. In which case the liquid absorbs all the mechanical energy while raising its own internal energy, but the liquid and steam do not rise above 212*F until after all liquid becomes steam. The amount of energy (BTU's) to turn a given weight of liquid water at 212*F into the same weight of steam at 212*F is known as Latent heat of vaporization.

http://www.engineersedge.com/heat_transfer/heat_work.htm

http://en.wikipedia.org/wiki/Heat

 

Keep in mind, an ac which is sound will only cool 15-20 degrees lower than ambient temp.
+1 on a leak check.