So here in Southern California we are getting some unusually hot weather for this time of the year, I had to work in Rialto about 30 miles from home so I stopped at McDonald's got myself an ice cream and hopped on to the I-210 fwy and headed East.

Traffic was good and I was averaging around 75-MPH, outside it was HOT, like in 100's but inside it was nice, it was cool, by the time I got to work I was downright FREEZING, I had to put on a pair of gloves because the air from the vents blowing onto the steering wheel was making my hands stiff and hurt.

I hate that when that happens

This was my inside vent temperature for about 30 miles.



In case you don't believe it, (using the digital to check calibration on the mechanical thermometer)



Have to admit though, after I got of the freeway it warmed up to 40*ish.

When I got off the freeway on Riverside Ave, I passed this, my AC had a 91.4* Temperature Differential



This is what helps my truck run so cold in traffic



My cab is so well insulated that when I got to work I turned off the AC and stayed inside the cold cab for about 10 minuets to warm up while I finished my ice cream before getting out into the 111* heat.

I worked in hot apartments and around hot A/C condenser fans for 8 hours in the sickening heat so
I turned on the A/C around 11:00 P.M. and blasted my way home.

Jim

 

How can you have an exit temp below freezing without freezing up the evaporator after a little time?

 

On my 2007.5 the exit temperatures are regularly minus 3 to minus 4 degrees Celsius or 26 degrees F. Thats just driving around town. They never freeze, but the water coming out of them is impressive.

 

Good question.

And why isn't the factory freezestat not taking the compressor offline?

 

It's dry out in California. If we east coast people tried that we would have a big ice cube in the heater box.

Sent from my Paranoid Android HD2 using Tapatalk 2.

 

I have vent temps down towards ~35deg F and if I don't keep the fan on med-high the evaporator will freeze up on me and then the air gets warm.

 

Yes that is for sure....I tried Jim's method of going around the cycling switch.....Iced up in a hurry....too much humidity.

Lucky dude.

He also hasn't converted to 134a which is another smart move on his behalf.

 

I go around the switch when me and the little woman go on a trip, but i have to shut off the compressor about every 30 min, to keep it from freezing up.

 

My 93 D350 is plenty cool, still bone stock. My 90 conversion van has a mixture of propane and isobutane in it for refrigerant, and is a dual evaporator system. You could hang meat in that van.

 

I have an almost new R12 system in my truck and it'll blow 20* because the compressor never kicks off, but freezes up in about 30 minutes of driving even running the blower on full blast. by that time i'm freezing my ***** off.

But my HVAC is also stuck on MAX A/C so it just keeps recirculating the inside cab air, instead of using the warm air from outside. the Vacuum actuator for the door is stuck.

 

My evaporator has only iced up probably less that half a dozen times since I have made my mods.

If I set the blower on the lowest speed and depending on the ram air, the temps will get down into the single digits and the air is blistering cold, at that point I have to be careful not to ice the evaporator.

I would be interested to see what my pressured are at this time and how many RPM's my compressor is turning at say 75-MPH.

Here is a peek at my pressure readings when I topped it off last week, I added just enough to clear the sight glass and no more.
This is at about 1000 RPM.



I also found out one day that my glove box gets cold enough to keep my lunch and a few cold drinks for later.
I just need to add some insulation to the backside of the box and take all of the junk out.

I can't find any air leaks back there but I have not spent too much time on this.





Some interesting ideas I have had for my AC are:

*Cold Plates under the seat and back of the cab, no evaporator to freeze.

*Remote fan driven condenser.

*12-volt hermetic compressor independent of engine.

With enough insulation there is no reason you cold not turn your cab into a refrigerated cooler, add a reversing valve then use it for heating.

I have worked on mobile AC units where the air has to be tempered so the occupants do not freeze to death.
Units powered by a separate 4-cylinder Perkins engine.

I had a Frigidaire A/C in my Mustang that would blow ice cold air and when the drain got pinched it would blow slush at you.

Jim

 

I hate you guys!

I am getting a vacuum thingy for my brakes tomorrow and it says I can test my vacuum lines. I am stuck on defrost and I need to clean the HVAC box yet. Blows cool, not cold though.

 

dieseljon, If you remove the glove box you can unhook the actuator and manual move the door so it comes out the vents.

your problem could also be the junky vacuum buttons in the controls on the dash.

 

Because the cycling switch is setting in my garage.

Jim

 

Running low air flow and cold evaporator can cause saturated or condensing refrigerant to get to the compressor, adding to the load, and increasing both pressure and heat. It's much more efficient to use high air flow, and make the evaporator completely evaporate the refrigerant so it's a dry gas when it gets to the compressor.


Condensation, mold, etc.



Interesting, especially if you have an engine overheat problem to deal with.


So with big deep cycle batteries you can run the AC when yer "parking"?


Why would you go to all that trouble to burn more fuel for cool when you have decatherms/hr of waste heat to dispose of anyway?