a/c freezes every 3 hrs?

Well, I'm back from my trip! We drove our little 94 SL2 across Florida this
weekend, what a fun drive! Only one thing that sucked, the A/C after 3 hrs
of straight driving froze over and stopped blowing air. We had to shut it
off for about 30 min. then it worked again.

We had the same thing happen with our 93 SL1 a few yrs ago, bu that car has
the old R12 coolant, my 94 SL2 has the newer R134. Doesn't matter if it's
hot or cool, raining or not, recirulator open or closed, thermostat high or
low, it happened going across west and then back east again, 3 hours and it
freezes over. WTF? I would hate to drive this car to Nevada or Arizona. Is
this normal? I can find no leaks, the car seems to be perfect in every other
way. Thanx.

 

Putting my Ac knowledge for homes and in hotels. when ever I found the ac
unites would freez up usally was due to pluged filers or the AC
condenser/radiator unit was plugged with debris..

Take a look and the front of the car in the ac radiator to see if it is
indeed pluged or clogged with leaves dirt and even a big chunk of paper..
Next I would look into the cars ac cooling unit in the heator box. this
little "radiator" in the heating box could also be plugged with sludge.

 

Could be a low refrigerant charge - I think that can cause the evaporator to
freeze up..

 

That caused the evaporator to freeze in my home's A/C.

Jerry

 

What they said -- low refrigerant or something blocking airflow. I
would suspect maybe a "door" isn't opening or some such, especially
if this happens with recirc on. Also make sure you don't have all
the outlet vents turned off. You probably need to have at least
half of them turned on to assure sufficient airflow, especially if
you run the fan on low.

 

Well, I just gopt back from Saturn. They could find nothing wrong, but they
did reset my compressor so thta it would cycle on / off more frequently.
They said that it would help to prevent the compressor from staying on too
long and freezing over.
They also checked my a/c cooolant (R134) and the evaporator lines, including
the drain tube and said that all was perfect with no clogs and the coolant
was neither too high nor too low.

Dan in reply:, the problem occured both with the recirculator on or off,
didnt matter, I tried, same result either way, ditto.
And I never close any of my vents.

So, it'll be awhile before we go cross-state again, see what happens next
time! Thanks for the help everyone!

 

If it happens with recirc on or off that suggests that recirc isn't
working right and a lot of outside air is getting into the cabin.
If recirc were working fully then eventually the air in the cabin
would become dry and frost buildup would stop.

I suspect the doors are messed up somehow.

 

is checking the recirc doors a major effort? is it something I can check
myself? I am pretty sure that the recirc works ok, as when we are stuck
behind a stinky truck (there are lots of them here) and I turn the recirc
button ON I am no longer bringing in stinky air from outside.