a/c blowing cold for a while then hot

[shimmersky]

hi everyone
so im starting to feel the heat here in vegas its over 100f today
something funny started with the a/c the other day
driving along and the a/c is working fine
then all of a sudden it just starts blowing ambient air
no more cooling!!

i thought it might be a refrigerant charge issue so i purchased a bottle kit type thing with a gauge to tell you if it needs a charge or not, it says it wont read correct if it is over 85f
and it said my system was in the red or in need of mechanical service(high pressure reading at the low a/c port)

the car seems to cool just fine until it seems to just get too hot(ambient) and then somthing stops it from blowing cold air
if i let the car sit for a while and cool down(engine) and start with full a/c it seems to work fine

i know this car has a pretty unique cooling system, but does anybody have any ideas or advice
maybe i just need to take it to my tech and have the system recharged

stay cool

[cdvs]

Check your fans for proper operation.

There are low and high pressure cut off switches.

[dannmarr]

1) low reading on the high side= a) lack of refrigerant or broken/leaky compressor discharge valves.
2) high reading on low side= a) expansion valve stuck in open position or overfeeding

[blue thunder]

This probably won't help out any but I wanted to relate my story so maybe it might. I have not had a consistent working A/C system for many years. Blows cold for a short time only and the cooling aspect shuts off. The fan still blows fine. I took it to a dealer about two mos. ago and everything checked fine idling in the garage. However, out on the road driving the air barely even came on. Shortly after this my idler pulley started to seize up making a squealing noise (the belt) until after a few days it started to smoke. I cut off the belt and installed a new pulley and ac belt. Guess what. The last few days my air stays on full time. I drove over 100 miles today and it worked fine. After all these years. Sometimes you get lucky. Maybe my old pulley was not performing correctly. Good luck with you're case.

Mike

[immortal_suby]

If the coolant temp gets too high the AC compressor will automatically shut down until the coolant temperature comes back down.

Try taking out the front grill for more airflow the next time you are out cruising on a 100 degree day and see if that helps. I remember another member here from arizona did that with good results.

[shimmersky]

all very good info
thanks to those that have replied
im leaning towards the coolant getting too hot
the system works fine here in the morning and at night and all other times
the only time it kicks off is when its real hot out and im sitting in traffic or going up the hill to my house

although i dont disregard a component failing in the system it just seems to be linked to ambient temps

any more ideas keep them coming

[shimmersky]

Originally Posted by immortal_suby

If the coolant temp gets too high the AC compressor will automatically shut down until the coolant temperature comes back down.

Try taking out the front grill for more airflow the next time you are out cruising on a 100 degree day and see if that helps. I remember another member here from arizona did that with good results.

how does the coolant temp affect the a/c system
if the car gets too hot is it a protective measure to shut down the compressor??

im not exactly sure as to the theory of operation with the a/c but how is the cooling system hooked in with the air con system

i have just installed a new silla radiator and just did a coolant flush as well

all very good info thanks