A/C efficiency in a Classic

No cabin filter here either..We cleaned the evaporator and it is blowing very good now..Still not cooling ''great'' in very HOT areas..It gives me a fighting chance..

 

Dash board AC is great for keeping you cool when your in the drivers seat. Not the bunk. I had a 07 Freight and it had a bunk ac outlet as well. It worked Ok. But APU is the best to have, it will freeze you out, at least mine does. OH one other thing, almost forgot, remember you still have a 180 degree motor down there idiling away. My truck will warm up 30 degrees after I shut the motor down.

 

Another thing is to turn off the valves to your heater core if it is so equipped

 

i tried the water off trick.

i've found the coldest air with the water still on. don't know why. and the vents on fresh air.

i dont' know who gets colder on recirculated but fresh is the way to be. recirculated never works for me. vents gets warmer. even on my cars.

 

might be the way yours works but mine blows at least 5 degrees warmer on fresh air(i have a temp. probe in my vents). max a/c setting shuts the outside air off and recirculates the cabin air in every vehicle i ever had

 

There is a filter on the inlet air under the hood, right side, on the black box, it is held in with a screw and cleans the air going into the cabin..
If the system is not properly serviced it will not work properly, When was the last time the dryer was changed? Is the oil level at the proper level? It needs to be evacuated, for at least 20 minutes, and then left to be sure there are no leaks. The proper amount of fluid must be added, the system pressures must be correct, or the expansion valves or whatever must be replaced.
The evaporator core can be covered in dust, like a felt pad. The Condenser core must be clean, To do that run the engine at about 1200 RPM and engage the fan, use a preasure washer and spray thru the grill straight in, in a close pattern. If you have a plastic bug screen, take it off, and after the cleaning install it and notice how much it blocks off airflow, Personally I call them JUNK.
When the system is properly maintained and no one installed any sealant or other JUNK, it will work perfectly. They make an arctic package that has insulation mats that really helps, and saves a lot of fuel, as well. I have seen many units with the floor spray foamed, that I do not know if it helps.
Using inside air for long periods of time can really degrade the air quality in the cab in about ten minutes.
Just a thought!

 

Is that from an odiferous steering wheel holder?

What on the inside is worse than the diesel exhaust and engine blow by from the outside?

Mine blows 38 at the dash. Never pulped the sleeper vents. I oughta now that I think about it.

 

I am a licenced HD mechanic, I got my licence in 1973, I have worked on equipment from steam to the most modern all my life, I drove for a while, before becoming a mechanic, and still drive every so often, I got my Class one licence at 17 years of age, and still have it. I worked for Freightliner for the best part of 20 years.
AC efficiency is controled by size of the components and the insulation efficiency of the cab and sleeper. It is not rocket science, if you order your truck with a insulation package it will stay cooler in the summer and warmer in the winter. Even the color of the truck makes a huge difference. Walk threw a parking lot and touch a black truck and then a white one.
We did a lot of retrofits from R12 to 134a and I still have the book telling you which units could be just evacuated and oil added and the freon changed to the units that needed new hard parts. Cleanliness of the components and proper air flow makes a huge difference.
Just a thought!

 

I was having this problem while out west last month. Sometimes I had no ac at all then suddenly it would come on but working at about 50% with it on max.
I found out that I had weak magnets in the compressor clutch. Soometimes they would not grab at all,other times they would half engage and slip.
a tap to the center of the clutch with the ac on and the engine running was all it took. Don't get youre hand in the fan!!! Find a rod and bend it to make a tool to prevent this.

 

The AC clutch on a class eight is easy to test, any more than 3 ohms and it is junk. They are easy to change and cheap.
Hitting anything will never make it better, it may get it to work for a short period, and it may hurt you or the clutch, then you have no fan belts.
Just a thought!