AC system is acting up

Also a few weeks ago the evap core did freeze up a few times, or at least I think it did. 95% sure. Stopped blowing cool and volume went way down until I let it thaw.

Edit, the engine fan seems to behave as expected.

 

A/C systems are very simple and easy to diagnose and fix. It is a pity, truly a pity that most repair shops do such a poor job when fixing this things. All they do is throw parts at them and hope for the best... Hardly ever works.

Assuming all electricals are working properly, system is charged and compressor is cycling as you stated above I can tell you right now that the problem, most likely, is in your expansion valve...

Freon at this point needs to be recovered, lines opened and inspected for contamination. If no contamination is present, replace both (front and back) expansion valves and dryer, evacuate system and recharge to specs.

If contamination is present, black oil or metal shavings mean compressor, sandy substance means bad dryer and foamy oil means humidity, replace faulty components as needed, flush components with brake cleaner and compressed air, leave the system open for a while to allow most of the brake cleaner and humidity from the compressed air to evaporate, put 6 to 8 Oz of oil (generally PAG-100) in the compressor or as close to it as possible, close the system, evacuate for at least an hour (this gets rid of whatever humidity and brake cleaner is left in there), recharge Freon to specs.

NOTE!
DO replace both expansion valves, dryer and whichever O-ring you touched on both of this procedures... Why? Well they are generally cheap, easy to access and prone to fail specially on aged systems... You don't wanna pay for Freon and/or labor again.

I can tell you which tools to buy if you wanna do it your self (less than 200 bucks).

GL!

 

Definitely expansion valve... You can say an expansion vale is a freon throttle, it lets measured amounts of freon to pass into the evaporator. It calculates how much freon the evaporator needs by "sensing" the outside temperature (pressure) and the temperature (pressure) of the returning freon... A sticky valve could cause ice buildups if it remains fully open or lack of cold air if fully close. I'll try to gather and post some material on this thread, I feel is about time we stop overpaying shops for guessing wrong. GL!

 

Hey, kW did you get your ac fixed?

 

If this system is in a Paccar, especially a KW the temp sensor in the evaporator sometimes goes mental, pulling the climate control fuse will make it blow full cold all the time that the A/C is turned on