On a long run it is as if the a/c just starts to die out.

At first I though it was the charge but the charge is fine. What I did notice is if I set it on a lower setting (fan setting) over a longer time it seems like it plugs up??? The air that does get through is not cold at all and gets warmer until it reaches the outside temperature. If I then turn it to fan air only (not on A/C) and put the fan on high speed over about 15 or 20 or so minutes the air starts to flow faster as if the plug up is cleared, I let it do this and then go back to a/c and the a/c blows ice cold again. I thought maybe my drain hole was plugging up but I checked and the car still pees on the ground. If it was freezing up wouldn't it take longer to thaw it out and have the a/c work cold,, it does seem like it is plugging up and the air flow is much less. If I run the a/c on maximum setting and maximum fan it will continue to work without issues. My fan is working fine as when it seems to plug up I can hear the fan running and trying to blow air but the air just seems restricted.

anyone have an idea??

 

It does sound like the evaporator is iceing up. If the ice is frost and not hard clear ice, it will freeze and thaw pretty quickly. On Max a door opens under the dash and it recirculates about 75% of the air from inside the car. That cuts down dramaticly the amount of humidity that's going through the cold evaporator. When it's set on normal AC, air is pulled in through the cowl up between the hood and the windshield. This is humid outside air. That sort of explains why it's iceing up faster on Ac and not on Max, although, I'll bet if you went on a long enough trip, it would ice on Max.

There's a piece in the system called an expansion valve. It's job is to regulate the temperature of the evaporator and keep it from iceing. Sounds like it's not working properly. It's located outside the firewall, where the AC lines attatch to the Evaporator. It's an Aluminum block with both hoses screwed into one side with a round disc on top. You have to drain the refrigerant out of the system, disconect the AC lines and remove the two bolts holding the valve in place. They are Torx or Allen, I forget which one. You should be able to get a replacement at any autoparts store. Install the new one, then the system should be evacuated(sucked out with a vacuum pump) to remove any moisture in the system. Then recharged with refridgerant.

 

When I go to fix it I will check this advice out.

I think I may just leave it for now though as I don't do many long runs with the car. The worst case scenario is that it ices up quicker and quicker as this expansion valve gets older and older right?? The a/c works great for me now.

Thanks for the clear explanation.

 

A/C would be bringing in outside air.
MAX A/C recirculates the inside air. MAX takes out more humidity and runs the system colder. So I think you'd get more water dripping with MAX. You're farther below dew point when running MAX.

Sounds to me like your low pressure cycle switch isn't working. Does the compressor ever turn off when you have the car running with the A/C on?

Without the low psi cutoff cycle switch working, your A/C will run forever and turn into ice. When the low psi cutoff is working, the 15 seconds of off time on the compressor will melt any ice in the system.

My car will blow freezing and sometimes below freezing temps (30-33°F), but no icing problems occur due to those off cycles melting any ice build up. (system turns the compressor off at 26 psi and back on at 47 psi). This is on my 3rd gen, so the 4th may be different. But I'd check the switch first.

 

Pearlpurple, I will agree with you, it's not enough of a problem at this point to have to do anything. It may never get worse. However, I looked at a 95' wiring diagram and there is something that I overlooked. There is an AC Evaporator Temp. Sensor. It's a temp. probe that is stuck through the evaporator which tells the PCM evap. temp. This sensor could be faulty, or have fallen out of the evaporator. If you have access to a scan tool, you can read the Evap. temp to see if it's way out of whack.

http://shbox.com/1/hvac_compressor_control.jpg

I still say that if you're pulling in outside humid air, there is more moisture in that air that the AC system has to pull out in the form of condensation. Running on Max, the AC does blow colder because it's cooling already cool, dryer air than more humid hotter air from outside the car.

 

Are the radiator fans both turning on when you turn the air conditioning on? If they're not, your condenser is going to have a heck of a time trying to shed that heat. The high pressure psi would be too high as a result.

Running the system on low fan speed (the ***** inside the car) pushes the condenser harder because it means the in cabin temp is going to be the coldest (which of course means the outside condenser has to shed that much more heat.

 

dude, what are your pressures at opperating temps?

 

I haven't gotten that far in troubleshooting.

I guess I am just looking for that Z28.com miracle cure

When I do get to that point I will post them.