10 replies to this topic

[split71]

So maybe you all can help me on my AC question. When im idle, the compressor engages and i've tested the low pressure switch with a paperclip also. It engages when it's hooked up to the dryer and with a paperclip. BUT when im idle, it's not really cold, it's kinda just room temperature and when it's hot outside it's not nice. But as soon as i get going down the highway it gets ice cold and stays cold. Now when i come to a stop and turn off the truck, it just dumps all the water underneath the truck and looks like a big puddle that should have been dripping while driving the whole time (snowball effect). Think i need to add Freon?

[mustash29]

IMO, you need decent air flow to keep removing all the radiator, engine & condenser heat in order for these systems to work well. My 91 Sonoma (RIP) , 01 Z and 03 BlaZ all had issues blowing ice cold when stopped in traffic, ideling, etc but all worked very well if > 30 mph.

The condensate drain from the HVAC system does drain right above the frame rail. Maybe yours is running into the frame & not dripping out due to mud, debris, etc inside the frame rails.

[mustash29]

When it's really humid are you running max (recirculating) or normal / bi level (drawing fresh air) ?

If you are running fresh air and your system gets really cold it can partially or entirely freeze the moisture onto the evaporator coil inside the HVAC box. Then when you shut down all that melts & drips out.

I used to have an 86 Escort that had a damn freezer for an A/C. It would get so cold running on max that when you switched to fresh air it would blow fog for about 30 - 60 seconds. I loved that, used to freak passengers out.

[split71]

When it's really humid are you running max (recirculating) or normal / bi level (drawing fresh air) ?

If you are running fresh air and your system gets really cold it can partially or entirely freeze the moisture onto the evaporator coil inside the HVAC box. Then when you shut down all that melts & drips out.

I used to have an 86 Escort that had a damn freezer for an A/C. It would get so cold running on max that when you switched to fresh air it would blow fog for about 30 - 60 seconds. I loved that, used to freak passengers out.

Well that's what i mean by the snowball effect. I try to run it from fresh air so it doesn't ice up the coil. I have to run it on recirc though sometimes just to keep it cool enough in the cabin until i can swap it over to fresh air..

So i don't need to add freon? It's normal for it to be somewhat warm air when idling?

[mustash29]

It's not supposed to run warm when ideling, but that's what happens with these somewhat over worked cooling systems.

The compressor pumps the freon up to high pressure, which builds heat. The condenser in front of the radiator gets rid of that heat, which makes the radiator warmer & may cause the clutch fan to engage, sucking more HP. The freon then goes through a small orifice (tiny hole) as it sprays into the evaporator coil (inside the dashboard). This flashing from high to low pressure is what makes the freon cold.

Very similar to how an air compressor discharge pipe will be hot, but the air coming out of the blow gun will feel cooler.

Basically at idle there is minimal airflow to keep things underhood cool, so the entire system runs warmer. Ever see a cop car sitting at an emergency with the hood popped open? That's letting the extra underhood heat escape.

Cooling 101: You have to remove the moisture from the air before the air starts to get cold. By driving around mostly on the fresh air settings you are getting slightly dehumifided air that is cool but not ice cold.

On max, you are recirculating the cabin air, so it gets much drier much quicker & then gets much colder.

If you have a very powerfull A/C system that is charged precisely and use the fresh air settings in very humid air you WILL freeze up the evaporator coil, then the blower can't blow any air across it.

Edited by mustash29, 03 August 2011 - 08:48 PM.

[split71]

Thanks for the info! I will just have to live with it i guess

[67Truckin]

The other part is the R134a freon that was used to replace the old R12 freon in automobiles. R134a is less effecient and doesn't cool as well when the engine is idling with the compressor on. You will notice if you speed up the engine and hold the rpm's to around 1000-1500 it will get cooler. That is pumping the freon faster which creates the cooling effect.

Just another 'great' way the government is protecting us from ourselves by banning R12 freon for the myth of global warming.

[jwwaldschmidt]

The other part is the R134a freon that was used to replace the old R12 freon in automobiles. R134a is less effecient and doesn't cool as well when the engine is idling with the compressor on. You will notice if you speed up the engine and hold the rpm's to around 1000-1500 it will get cooler. That is pumping the freon faster which creates the cooling effect.

Just another 'great' way the government is protecting us from ourselves by banning R12 freon for the myth of global warming.

Very true. The Avy has digital climate control, it automatically switches over to recirculation every time I get below 10 mph... it's the only way to keep it cool.

It shouldn't get warm though. You might check your pressure readings, I think you may be a little low on freon.

[split71]

The other part is the R134a freon that was used to replace the old R12 freon in automobiles. R134a is less effecient and doesn't cool as well when the engine is idling with the compressor on. You will notice if you speed up the engine and hold the rpm's to around 1000-1500 it will get cooler. That is pumping the freon faster which creates the cooling effect.

Just another 'great' way the government is protecting us from ourselves by banning R12 freon for the myth of global warming.

Yes i did notice that when i give it a little gas it gets cooler. That's why i thought it may need a little bit of freon.

The other part is the R134a freon that was used to replace the old R12 freon in automobiles. R134a is less effecient and doesn't cool as well when the engine is idling with the compressor on. You will notice if you speed up the engine and hold the rpm's to around 1000-1500 it will get cooler. That is pumping the freon faster which creates the cooling effect.

Just another 'great' way the government is protecting us from ourselves by banning R12 freon for the myth of global warming.

Very true. The Avy has digital climate control, it automatically switches over to recirculation every time I get below 10 mph... it's the only way to keep it cool.

It shouldn't get warm though. You might check your pressure readings, I think you may be a little low on freon.

Yeah i may add a little just to see if it helps. I don't want to blow the seals on the compressor..

I know what you mean about the digital climate control. In my Audi S4 that thing has a big ass V8 packed in under the hood and it always stays close to ice cold when driving then idling. I just wish my truck could do that

[67Truckin]

With the high temperature and high humidity causing heat indexs in the 100's the air conditioners are really working hard to offset the heat. I've had several customers lately complaining of the same thing and the pressures were fine. It just takes time to get the internal temperatures cool when a closed car can be 120-150+ degrees inside. Even the dash and air conditioner ducts are at that temp internally so it will be hard to cool down quickly. If your high and low side pressures are in range and the engine is not idling, it will just take alittle time.

[jwwaldschmidt]

The other part is the R134a freon that was used to replace the old R12 freon in automobiles. R134a is less effecient and doesn't cool as well when the engine is idling with the compressor on. You will notice if you speed up the engine and hold the rpm's to around 1000-1500 it will get cooler. That is pumping the freon faster which creates the cooling effect.

Just another 'great' way the government is protecting us from ourselves by banning R12 freon for the myth of global warming.

Yes i did notice that when i give it a little gas it gets cooler. That's why i thought it may need a little bit of freon.

The other part is the R134a freon that was used to replace the old R12 freon in automobiles. R134a is less effecient and doesn't cool as well when the engine is idling with the compressor on. You will notice if you speed up the engine and hold the rpm's to around 1000-1500 it will get cooler. That is pumping the freon faster which creates the cooling effect.

Just another 'great' way the government is protecting us from ourselves by banning R12 freon for the myth of global warming.

Very true. The Avy has digital climate control, it automatically switches over to recirculation every time I get below 10 mph... it's the only way to keep it cool.

It shouldn't get warm though. You might check your pressure readings, I think you may be a little low on freon.

Yeah i may add a little just to see if it helps. I don't want to blow the seals on the compressor..

I know what you mean about the digital climate control. In my Audi S4 that thing has a big ass V8 packed in under the hood and it always stays close to ice cold when driving then idling. I just wish my truck could do that

Don't just add freon, find someone with a set of gauges. Check your readings first.

With the high temperature and high humidity causing heat indexs in the 100's the air conditioners are really working hard to offset the heat. I've had several customers lately complaining of the same thing and the pressures were fine. It just takes time to get the internal temperatures cool when a closed car can be 120-150+ degrees inside. Even the dash and air conditioner ducts are at that temp internally so it will be hard to cool down quickly. If your high and low side pressures are in range and the engine is not idling, it will just take alittle time.

This.